42
© Woodhead Publishing Limited, 2013 14 Conventional and alternative technologies for the extraction of algal polysaccharides G. Hernández-Carmona, Instituto Politécnico Nacional, México, Y. Freile-Pelegrín, CINVESTAV-IPN, Unidad Mérida, México and E. Hernández-Garibay, Centro Regional de Investigación Pesquera de Ensenada, INAPESCA, México DOI: 10.1533/9780857098689.3.475 Abstract: Alginates, agar and carrageenan are the main commercial water-extracted polysaccharides sourced from brown and red marine algae. These phycocolloids exhibit high viscosity, and stabilizing, emulsifying and unique gelling properties. Agar and carrageenan form thermoreversible gels while alginates form ionic non-thermoreversible gels; therefore they play an irreplaceable role in foods, pharmaceuticals and biotechnology. The phycocolloid industry uses seaweeds from different parts of the world, and phycocolloid production amounts to 86 100 tons annually; equivalent to US$ 1018 million. In this chapter we describe the conventional processes adopted in most factories for extracting and processing alginates, agar and carrageenan, and discuss the use of new eco-friendly extraction processes. Key words: seaweeds polysaccharides, alginate, agar, carrageenan, phycocolloid process. 14.1 Introduction The phycocolloids alginate, agar and carrageenan are the main commercial polysaccharides derived from seaweeds. These three hydrocolloids are widely used in the food industry, pharmaceutical industry and in biotechnology, among other applications, because of their ability to produce highly viscous solutions and/or gels. As the first phycocolloid used, agar was one of the first

Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

  • Upload
    others

  • View
    17

  • Download
    0

Embed Size (px)

Citation preview

Page 1: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

© Woodhead Publishing Limited, 2013

14

Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit é cnico Nacional, M é xico , Y. Freile-Pelegr í n, CINVESTAV-IPN, Unidad M é rida, M é xico and E. Hern á ndez-Garibay, Centro Regional de Investigaci ó n Pesquera de Ensenada, INAPESCA, M é xico

DOI: 10.1533/9780857098689.3.475

Abstract: Alginates, agar and carrageenan are the main commercial water-extracted polysaccharides sourced from brown and red marine algae. These phycocolloids exhibit high viscosity, and stabilizing, emulsifying and unique gelling properties. Agar and carrageenan form thermoreversible gels while alginates form ionic non-thermoreversible gels; therefore they play an irreplaceable role in foods, pharmaceuticals and biotechnology. The phycocolloid industry uses seaweeds from different parts of the world, and phycocolloid production amounts to 86 100 tons annually; equivalent to US $ 1018 million. In this chapter we describe the conventional processes adopted in most factories for extracting and processing alginates, agar and carrageenan, and discuss the use of new eco-friendly extraction processes.

Key words: seaweeds polysaccharides, alginate, agar, carrageenan, phycocolloid process.

14.1 Introduction

The phycocolloids alginate, agar and carrageenan are the main commercial polysaccharides derived from seaweeds. These three hydrocolloids are widely used in the food industry, pharmaceutical industry and in biotechnology, among other applications, because of their ability to produce highly viscous solutions and/or gels. As the fi rst phycocolloid used, agar was one of the fi rst

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 2: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

476 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

food ingredients approved as GRAS (Generally Recognized as Safe) by the FDA (Food and Drug Administration).

The use of phycocolloids in the food industry as functional food products is largely based on their ability to form gels, and the unique properties of these gels. Agar and carrageenans produce thermoreversible gels, where agar melts at a higher temperature than carrageenans. Carrageenans further have the ability to bind proteins in milk and meat products, while the gels rendered by alginates are ionic non-thermoreversibles. The main commercial sources for alginate production are the brown seaweeds Laminaria (Europe and Asia), Ascophyllum (Europe) and Lessonia (Chile and Peru). For agar, Gracilaria and Gelidium are the preferred seaweeds, while Kappaphycus , Eucheuma and Chondrus are used for carrageenans. Agar is the most expensive colloid, at US$18 per kg, followed by alginates and carrageenan at US$12 per kg and US$10.5 per kg, respectively. The total volume of phycocolloid production in 2009 was 86 100 tons; equivalent to US$1018 million. Of this total, car-rageenans accounted for 50 000 tons (58%), producing an income of 527 mil-lion US$ (52%), alginates accounted for 26 500 tons and agar for 9600 tons, representing 32% and 17%, respectively, of the total sales. The process of producing alginate involves pre-treatment of the seaweeds with HCl (pH 4), extraction of the alginate with Na 2 CO 3 solution (pH 10, 80 º C, 2 h), and dilu-tion and fi ltration in a vacuum rotary fi lter. The recovery of the alginates is then carried out as the insoluble calcium-alginate. Conversion of the insoluble alginate to soluble is achieved by treating the fi ber, fi rst with acid, then with Na 2 CO 3 to obtain sodium alginate. Quality control for alginates is focused on particle size distribution, viscosity, pH, ash and calcium content.

For agar, the conventional production process includes pre-treatment, extraction, fi ltration, concentration and dehydration. However, depending on the genus used, there are some differences in the pre-treatment step. For Gelidium , this stage consists of a corrective treatment with a mild alkaline solution. This eliminates phycoerythrine and prepares the seaweed for a more effi cient extraction. For Gracilaria , the alkali treatment is performed before extraction to increase gel strength. However, the effl uents produced by this conventional method constitute a pollution problem. In response to these problems, the use of ‘green’ technology to produce large quantities of aga-rophytes as Integrated Multitrophic Aquaculture (IMTA) systems, together with the use of eco-friendly agar extraction methods, are proposed as the key to the future of the agar industry.

In carrageenans the process is rather more complicated, and largely depends on the species used. There are two basic processing lines, one for the produc-tion of refi ned carrageenan, in which an extraction at high temperature is followed by fi ltration and precipitation with alcohol or potassium chloride (KCl), and the other is for the production of semi-refi ned carrageenan, in which the carrageenan is not actually extracted. In this process, the seaweeds are generally alkali treated and the gel strength increased by concomitant desulfation. Some impurities, such as proteins, pigments and minerals are

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 3: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 477

© Woodhead Publishing Limited, 2013

eliminated, and the seaweed are then dried and milled. There are some other mixed procedures available and, as previously mentioned, in order to dimin-ish the environmental impact, the use of eco-friendly extraction techniques are necessary.

14.2 Alginates

Alginate is a structural phycocolloid of brown seaweeds. Alginate has the ability to form heat stable gels with some divalent metals. It is an ionic poly-saccharide comprising salts of two residues: β -D- mannuronic acid (M) and α -L-guluronic acid (G). These units are randomly distributed in a linear chain, where they can be arranged as homogeneous blocks MM or GG and alter-nates as MG. The physical properties of alginates depend on the proportion of the three types of blocks and are related to the seaweed source. Alginates with high G have higher gelling properties, whereas those with high M have higher viscosity. Alginates are obtained by acid pre-treatment, followed by an alkaline extraction. The extract is clarifi ed by vacuum fi ltration in order to remove seaweed particles, and the alginate is recovered from the solution as insoluble fi ber by precipitation with calcium salts. The insoluble calcium alg-inate is converted to soluble sodium alginate by treating it with acid fi rst, fol-lowed by a sodium carbonate–ethanol treatment. The fi nal product is dried, milled, and sold as powders of different mesh size. Alginates are widely used in industries to give consistency (viscosity) or to form gels. For example, it is used in baked foods, textile prints, beer foam stabilizers, welding rods, pill dis-integrators, bandages and dental impression material, among many others.

14.2.1 Historical background Alginate was discovered by Stanford in 1881, but it was not until 1923 that exploration of its potential really began when Thornley established a briquette business using alginate as a binder of anthracite dust. In 1927 he moved his company to San Diego, California, to produce alginate to seal cans. After some diffi culties, the company changed its name to Kelp Products Corp and in 1929 it was reorganized as Kelco Company. Alginate production then started on a large scale in San Diego, California. Production in the United Kingdom was established in the period 1934–1939 and in Norway some years later, after World War II (McHugh, 1987).

14.2.2 Sources of alginophytes The main commercial sources and amounts harvested per year (dry tons) up to 2009, in order of quantity, were: Laminaria spp. (30 500 t from: France, Ireland, United Kingdom, Norway); Lessonia spp. (27 000 t from Chile

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 4: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

478 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

and Peru); Laminaria spp. (20 000 t from China and Japan); Macrocystis pyrifera (5000 t from USA, Mexico and Chile); Durvillaea antarctica (4500 t from Australia), Lessonia fl avicans (4000 t from Chile and Peru), Ecklonia maxima (2000 t from South Africa); Ascophyllum nodosum (from France, Iceland, Ireland, United Kingdom) (Fig. 14.1). A drastic reduction in the harvest of Macrocystis pyrifera has recently occurred. This was origi-nally harvested on the west coast of North America, from the Monterey Peninsula in central California to the middle West coast of the Peninsula of Baja California (Mexico). The harvest was reduced from 35 000 t (1999) to 5000 t (2009), after the closure of the International Specialty Products facil-ity in San Diego. Another dramatic case relates to Ascophyllum , production of which decreased from 13 500 t (1999) to 2000 t (2009), mainly because its alginate produces low strength gel (low G blocks) whilst the market is demanding high G alginate (Bixler and Porse, 2011). At present, the main alginate producers are: China (Bright Moon), Norway (FMC BioPolymer, previously Kelco and Pronova); France (Cargill, previously Degussa, and Danisco); Japan (Kimica and Chemifa Food), and Chile (Kimica). Only China, Japan and Chile are producing propylene glycol alginate (PGA). Total alginate sales for 2009 were 26 500 t, with a total value of US$318 million

AlginophytesAscophyllumEckloniaDurvillaeaLaminaria spp.

Gelidium

Gigartina

Chondrus crispusBetaphycus gelatinum

Eucheuma denticulatumKappaphycus alvarezii

GracilariaPterocladia

Lessonia spp.Lessonia flavicansMacrocystis

Agarophytes Carrageenophytes

Phycocolloids production (2009)

Ton million USd

Agar

Carrageenan

Alg

inate

Agar

Carrageenan

Alg

inate

2650050000 527

173

318

9600

Fig. 14.1 Geographical distribution of commercial seaweeds used for phycocolloids production. Production and cost of phycocolloids in 2009. Data from Bixler and

Porse (2011).

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 5: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 479

© Woodhead Publishing Limited, 2013

(US$12/kg) (Fig. 14.1). The current price (2012) of sodium alginate increased to about US$17–19/kg and PGA is US$25–26/kg (Dennis Seisun, written communication; www.hydrocolloid.com).

14.2.3 Chemistry of alginate The chemical compounds extracted from seaweeds which facilitate the forma-tion of viscous solutions or gels are polysaccharides named phycocolloids. The main commercial phycocolloids are alginate from brown seaweeds, and agar and carrageenan from red seaweeds (McHugh, 1987). Alginates form part of the cell wall and inter-cellular matrix of all the brown seaweeds. In the seaweed, the alginate provides the fl exibility and the mechanical strength required by the plant to survive in the sea. In their natural state, alginates are bonded with all of the salts present in the seawater, particularly Ca 2+ , Na + , Mg 2+ , Sr 2+ and Ba 2+ ions (Haug, 1964).

Alginate is a linear polysaccharide co-polymer of (1–4)- linked β -D-mannuronic acid (M), and α -L-guluronic acid (G). The two residues are arranged in an aleatory way within the alginate molecule. Three types of seg-ment or blocks can be distinguished within the alginate: two homopolymeric, MM and GG, and one heterogeneous or alternating MG. (Haug, 1964; Haug et al. , 1966; Smidsrod and Draget, 1996; Draget et al. , 2005; Murillo- Á lvarez and Hern á ndez-Carmona, 2007). Different raw materials feature different M and G content, and the alginate properties of a particular seaweed are depen-dent on both the M/G ratio and the block distribution within an alginate molecule (Haug et al. , 1966).

14.2.4 Alginate in food applications and other uses Alginates are widely used across a number of different industries. They give consistency and an appropriate appearance to dairy products and canned foods, help retain moisture, thus improving the texture of baked foods, and ensure a smooth texture and uniform dewatering in frozen foods. Alginates are used as ink paste thickeners for textile prints, whilst in the paper industry they provide a smooth surface with less fl uff. More usual applications are as beer foam stabilizers, and as a material in welding rods. In medicine, alginates are used as pill disintegrators and for bandages that are absorbed by the body (and thus do not have to be removed). Alginates are also used as a compo-nent of dental impression material (McPeak and Glanz, 1984; Reyes-Tisnado et al., 2004).

14.2.5 New insights into alginate uses Alginates are now used to treat gastric ulcers, lower cholesterol levels and inhibit the granulation of mast cells, which are involved in allergic reactions (Nagaoka et al. , 2000). Alginates fi nd novel applications in the immobilization

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 6: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

480 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

of benefi cial microorganisms for waste water treatment, and as a plant growth promoter, (Iwasaki and Matsubara 2000; Yabur et al. , 2007). More recent applications are as proteins carriers (Coppi et al., 2001), metal interchang-ers (Davis et al., 2004; De Stefano et al., 2005), new textiles (Goren š ek and Buko š ek, 2006), yeast immobilization (Pajic-Lijakovic et al., 2007), micro beads (Schuldt and Hunkeler, 2007; M ø rc 2008), UV ray absorption (Tavares-Salgado 2007) and control of ulcerative colitis (Alireza-Razavi et al., 2008). Indirect uses are also found in the transformation of residuals from the alg-inate extraction for use as fertilizers, because the bacterium Gracilibacilus (A7) degrades the alginate to oligosaccharides during the composting process (Tang et al. , 2009). These residues can also be used for bioethanol production, since they are rich in sugars such as manitol and laminaran, drastically redu-cing the cost of production (Moen et al. , 1997; Horn et al. , 2000 ).

14.3 Conventional alginate extraction methods

The foundation of alginate extraction from seaweeds is the conversion of all alginate salts into soluble sodium alginate, dissolution of the alginate in water and the removal of insoluble residues. Following this, a calcium salt is added to form calcium alginate, which is an insoluble fi ber and can be easily removed from the residual water. The fi bers are converted to alginic acid by treatment with a hydrochloric acid solution. The fi bers are then separated and blended with alcohol and sodium carbonate to convert them to sodium alginate. Other salts like potassium can be used to obtain potassium alginate. The sodium alg-inate is pressed, dried and milled (McHugh, 2003) (Fig. 14.2). The extraction processes used by many authors employ chemical preparations at fi xed con-centrations (normal or percent), for example sodium carbonate at 1% for the extraction step (Nishigawa, 1985; Istini and Kusunose, 1994; Calumpong et al. , 1999; Younis et al. , 2000; Fenoradosoa et al. , 2010). However, it has been found that it is better to control the process by controlling the pH in the different steps, to prevent the yield and quality of the alginate being produced.

14.3.1 Reduction of the seaweeds In order to facilitate the transport of the seaweeds and to speed up the chemi-cal reactions, it is necessary to reduce the size of the raw material. The seaweeds must contain 83% dried matter (17% moisture), and less than 3% sand. Milling is usually carried out in a hammer mill, and is generally conducted when the dry seaweeds arrive at the factory. The milled product must meet the following size distribution: 100% less than 6 mm; 95% less than 3.3 mm; 2% less than 0.3 mm.

14.3.2 Rehydrating the seaweeds In order to soften the seaweed tissue and avoid alginate pigmentation, the sea-weeds are rehydrated with 0.1% formaldehyde solution (37.5% purity), for 1 to 12 h, depending on the species. The solution reacts with phenolic compounds, polymerizing and making the coloring substances insoluble. The ratio is one part

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 7: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 481

© Woodhead Publishing Limited, 2013

seaweeds to nine parts water. This proportion should be minimized to the point that all water is absorbed by the seaweed and no water is left at the end of the hydration. The increase of alginate yield using formaldehyde treatment has been previously documented (Hern á ndez-Carmona et al., 1999a; Davis et al. , 2004).

14.3.3 Acid pre-extraction Some authors mention that acid treatment is necessary to convert the alg-inate salts (Ca 2+ , Na + , K + , etc.) to insoluble alginic acid. This ionic exchange is not necessary for most species and the acid washing is useful only for the removal of external salts and residual formaldehyde. On the contrary, acid treatment at a pH lower than 4, as recommended by other authors (Haug,

Rehydrating the seaweeds

Acid pre-treatmentHCl, pH 4

Dilution and filtration

Precipitation of calcium alginate

Conversion of calciumalginate to alginic acid

Pressing and coversion ofalginic acid to sodium

alginate

Drying, milling, andblending

Sodium alginate

ExtractionNa2CO3, pH 10, 80°C

Fig. 14.2 Flow diagram for alginate production.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 8: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

482 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

1964; Myklestad, 1968; Hern á ndez-Carmona and Aguirre-Vilchis, 1987), may produce depolymerization of the alginate and reduce the viscosity (Hern á ndez-Carmona et al., 1999a). The hydrated seaweeds are placed in a tank with water, at a ratio of one part dried (starting weight) seaweeds to ten parts water. This amount of water should be enough to allow free agitation. Industrial hydrochloric acid (28% purity) is then added until pH 4 is reached in the solution. The seaweeds are stirred for 15 min at room temperature, and the residual solution is then drained. For best results, the seaweeds are washed with water (1:10) for 15 min (McHugh, 1987; Arvizu-Higuera et al. , 1995; Hern á ndez-Carmona et al. , 1999a).

14.3.4 Extraction To extract the alginate from the seaweeds, they are transported to an extrac-tion tank (kettle with steam jacket), and water is added in the proportion of one part of the initial dried seaweeds to 16.6 of water. This volume may change depending on the species. For seaweeds that produce low viscosity alginates (i.e. Sargassum ) less water is required (Rodr í guez-Montesinos et al. , 2008). The seaweed-water mixture is heated to 80 ° C, and enough sodium car-bonate powder is added to reach pH 10. The amount of water may be adjusted to obtain a paste that can be mixed, but is still thick enough to produce high friction between the solution and the seaweeds, to favor the alginate extrac-tion. It is useful to monitor the increase of the ‘process viscosity’ (Hern á ndez-Carmona et al. , 1999b) with a viscometer, as an indirect measurement of the reaction progress. The maximum viscosity will determine the maximum alginate yield to be obtained. A fi nal viscosity value for some species, like M. pyrifera, would be 3000–4000 mPa·s after two hours. The pH may be reduced during this process, which should be counteracted by the addition of more sodium carbonate to maintain pH 10. This step can be used to control the required viscosity of the alginate. High temperatures and longer process-ing times will produce alginates with lower viscosity, because of depolymer-ization of the polymeric chain of the alginate (Truus et al. , 2001). At the end of the extraction, the seaweed must be practically disintegrated (McHugh, 1987; Arvizu-Higuera et al. , 1996; Hern á ndez-Carmona et al. , 1999b). The extraction time (2 h) was confi rmed for Laminaria digitata (Vauchel et al. , 2008b), and the increase of alginate yield using a temperature of 80 ° C has also been demonstrated for the genus Sargassum (Davis et al. , 2004).

14.3.5 Dilution and fi ltration The paste obtained after the extraction step is pumped into a heated tank fi tted with an agitation device. To allow the fi ltration process to occur, water is added to reduce the viscosity to 45 mPa·s (at 75 ° C). For species like M. pyrifera , the volume of water needed to reach 45 mPa·s corresponds to one part of the initial dried seaweeds to 55 parts of water. After the viscosity

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 9: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 483

© Woodhead Publishing Limited, 2013

and temperature have been adjusted, the solution is pumped to a rotary vacuum drum fi lter (http://www.alarcorp.com/equipment/auto-vac) that effectively removes solid particles from the sludge, producing dewatered, dry seaweed residue and a clear alginate solution. The fi lter consists of a hollow cloth-covered drum rotating on a hollow shaft, while partially immersed in a pan. The shaft is connected to a vacuum pump, and the fi lter is pre-coated by feeding a suspension of fi lter aid in water into the pan. The vacuum pulls the fi lter aid onto the cloth, building up a layer of fi lter aid. The alginate solu-tion is then fed into the pan, pulled through the fi lter aid by the vacuum, and fed out via the hollow shaft. As the solution is pulled through this layer of fi lter aid, the fi ne solid particles in the solution are deposited on the surface. A knife blade is arranged to move slowly and automatically on the surface of the fi lter aid, shaving off a thin layer as the drum rotates and leaving a clean surface for rapid fi ltration (modifi ed from Alar, 1991). Some of the best fi lter aids are the diatomaceous earth (Celite 545) and the expanded lava (perlite), which is more economical (McHugh, 1987; Hern á ndez-Carmona et al ., 1999b).

14.3.6 Calcium alginate precipitation The clarifi ed alginate solution is pumped from the fi lter into the precipita-tion tank. A shower nozzle should be installed at the end of the pipe to spray-discharge the solution in drops. At the same time, a 10% calcium chlo-ride (CaCl 2 ) solution is added. The total amount of calcium to be added corresponds to two times the total alginate in solution to be precipitated. Both solutions are added simultaneously at a synchronized speed, so both solutions are programmed to fi nish at the same time. The agitation speed is important; a speed that is too slow will produce a clot-type precipita-tion, while a speed that is too fast will produce small fi bers, increasing the diffi culty of separating the alginate from the solution. The agitation speed should be increased as the solution volume in the tank increases. It is there-fore necessary to be equipped with a variable speed agitator. The calcium alginate fi bers are left in the tank for 15 minutes to allow the reaction to proceed. The fi brous calcium alginate can then be recovered by passing the suspension through a stainless steel screen (McHugh, 1987; Hern á ndez-Carmona and Casas-Valdez, 1985; Arvizu-Higuera et al ., 1997; McHugh et al. , 2001).

14.3.7 Conversion of calcium alginate to alginic acid The fi bers of calcium alginate are transformed into alginic acid via acid treat-ment. This step is carried out in three counter-current steps, using three square tanks with stirrers. The calcium alginate is transported to the fi rst tank, which contains acid previously used in the second tank. After stirring for 15 min, the solids are transported to the second tank using an endless screw with mesh at

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 10: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

484 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

the bottom. This second tank contains acid previously used in the third tank. The stirring and transportation are repeated, and the solids are fed to the third tank which contains new, diluted hydrochloric acid. The pH is adjusted to 2 in the fi rst tank, and pH 1.8 in the second and the third tanks (McHugh, 1987). If water is not limited, the alginic acid fi bers could then be washed with water for 15 min. The alginic acid must be almost free of calcium ions. However, if calcium is required in the fi nal product (to increase the viscosity of the alginate solution), the pH in the tanks should be increased to pH 2, 2 and 1.8, respectively, limiting the ionic exchange. The alginate viscosity of a 1% solution is measured during quality control testing, before and after adding a calcium-sequestering agent (sodium hexametaphosphate). Viscosity will be reduced after adding the salt, but the reduction should not be more than 40%, so the amount of calcium in the fi nal product should therefore be limited (Arvizu-Higuera et al ., 1997; McHugh et al. , 2001; Rodr í guez-Montesinos et al. , 2005).

14.3.8 Pressing and conversion of alginic acid to sodium alginate The alginic acid is pressed to remove excess water using a screw press or S-press. Materials like alginic acid that tend to pack or are otherwise con-sidered unpressable can be successfully processed using this equipment. The water is continuously drained from three areas of the press, reducing the hydraulic load. The screw press is equipped with a separate main drive and cone motors for independent speed control and retention time in the press. The alginic acid should contain 25% solids for the next step (modifi ed from Bepex: http://www.bepex.com/spress.htm)

The alginic acid fi bers are placed in a double planetary mixer, and enough alcohol is added to maintain a 55:45 alcohol:water ratio. For an estimation of the appropriate alcohol level to be used during neutralization, it is neces-sary to determine the amount of water remaining in the alginic acid fi bers. This is obtained by subtracting the expected weight of the dry alginate (based on prior analysis in the laboratory) from the weight of the wet alginic acid. An additional option is to determine the moisture content of alginic acid. For example, a sample of pressed alginic acid (wet) with a starting weight of 23 kg contains 2.3 kg of sodium alginate, and is estimated to contain 20.7 L of water. This accounts for 55% of the content, so the volume of alcohol needed to obtain a proportion of 45% is found as follows: V = (45 × 20.7) / 55 = 16.9 L. Therefore 16.9 L of alcohol should be added to the fi bers.

The next step is to add enough Na 2 CO 3 powder to achieve a pH of 8 in the fi bers. After stirring for 15 minutes the pH is measured; a sample of the fi bers is dissolved in water and the pH is measured in the solution with pH paper. Alcohol may cause some interference in the pH measurement, and generally the pH of the alginate in solution will be one point lower than the pH mea-sured in the fi bers with alcohol. The approximate amount of Na 2 CO 3 to add

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 11: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 485

© Woodhead Publishing Limited, 2013

is 0.25 parts per one part of the sodium alginate to be obtained. In this step the Na 2 CO 3 can be replaced for K 2 CO 3 to obtain potassium alginate. At this stage, the function of the alcohol is to keep the sodium alginate insoluble during the conversion process. Because alcohol is expensive, this must subse-quently be recovered by distillation to reduce costs. It is estimated that only 2% of alcohol will be lost in the recovery operation.

Sodium alginate can also be obtained without the use of alcohol. To do this, the alginic acid is directly mixed with sodium carbonate. However, in this case the fi brous consistency is lost and the product must be passed through an extruder to obtain pellets. These pellets are subsequently dried and pulverized (McHugh, 1987; Arvizu-Higuera et al. , 2002; Hern á ndez-Carmona et al. , 2002).

14.3.9 Drying, milling and blending Drying is carried out on trays in a hot-air oven at 60 ° C until the alginate reaches 12% moisture. On a large scale, is better to use a fl uidized-bed dryer with a vibrating screen and hot air blowing up through the screen (McHugh, 1987). Milling is carried out in a turbine mill or fi xed hammer mill. Most alginate products require a particle size lower than 60 mesh (250 microns), which can be achieved using a 3 mm mesh on the miller. To obtain a smaller particle size, the fi ne particles are separated and the coarse particles are milled with a 0.5 mm mesh size. In some cases a smaller size is required, and a third milling is then necessary. To separate the alginate by size, a fi ve vibration mesh system is used with the follow size meshes: 30 (0.594 mm), 60 (0.250 mm), 80 (0.177 mm), 100 (0.149 mm) and 120 (0.125 mm). If the alginate is fl uffy, it is harder to obtain fi ne alginate particles. Even after a third milling, 16% of the particles still will not pass through mesh 30 (Hern á ndez-Carmona et al., 2002). More expensive modern equipment for drying, milling and screening is available (Fig. 14.2).

14.3.10 Quality control The alginate obtained is analyzed in the laboratory to determine the viscosity of the product in 1% solution. The quality of the alginates (in terms of vis-cosity) varies according to various biological, environmental and processing factors. Therefore the products obtained may have different viscosities and should be blended to provide consistent quality. For blending the alginate a ‘V’-type blender can be used. The varied viscosities obtained from different batches can be combined to produce a specifi c viscosity: alginates with viscos-ity of 800 mPa·s can be produced by blending batches from 600 to higher than 1000 mPa·s. Alginates with mPa·s are produced by blending batches from 150 to 600 mPa·s; alginates with 80 mPa·s are obtained by blending batches from 40 to 150 mPa.s and products with 30 mPa·s are prepared by blending batches from 10 to 80 mPa·s. Generally, the fi nal product is packaged in cardboard

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 12: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

486 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

kegs of 22.5 kg with a plastic bag inside. Alginates are analyzed for the fol-lowing properties:

Viscosity in 1% of the solution, both before and after the addition of 0.5% • of sodium hexametaphosphate. Viscosity is measured with a viscometer and the product is classifi ed for sale by its viscosity according to the fol-lowing ranges (mPa·s): very low (25–35), low (70–100), medium (340–460) and high (680–920). The pH of the alginate solution, which, at 1%, should be 6.1–7.8. • Particle size distribution. The regular products are sold at particle sizes • between 30 and 60 mesh and the refi ned between 100 and 150 mesh. Moisture, which must be less than 12%. • Ash, the standard is in the range 18–27%. • Calcium content, the standard is between 0.3% and 1%. • Purity, which should be between 96% and 98% (Food Chemical Codex, • 1981; Kelco, 1996).

14.3.11 Future trends in alginate extraction An alternative method proposed for the alkaline extraction step employs a twin-screw extruder, and is called reactive extrusion. This technique appears to be more effi cient than batch processing in a number of ways: process time is reduced to a few minutes, water and reactant are reduced, yield may be increased by 15%, and rheological properties are enhanced. All of these enhancements are due to the high level of shearing and mixing effi ciency with the reactant. The reduced processing time lowers the level of depolymeriza-tion phenomena, thus increasing the alginate quality. This is a continuous process that makes the alginate extraction interesting from both an economic and an environmental perspective (Vauchel et al., 2008a, 2008b). Yield is also increased because of the reduced quantity of seaweed particles in the process (Vauchel et al., 2009).

14.4 Agar

Agar is a strongly gelling hydrocolloid from marine red algae. Its main structure is chemically characterized by repetitive units of D-galactose and 3,6-anhydro-L-galactose. Substitution with sulfates, methyl ethers, and/or pyruvate ketals can occur at various sites in the polysaccharide chain. The substitution pattern of these groups depends on both the algae species and the extraction method used which can promote desulfation, causing an increase in agar quality. In Gelidium and Pterocladia , desulfation occurs as a natural internal transforma-tion through an enzymatic process, whereas in Gracilaria it is not converted in the needed amount during the seaweed’s lifetime. Therefore when agar is

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 13: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 487

© Woodhead Publishing Limited, 2013

produced at an industrial level, it is necessary to promote desulfation by means of a chemical method before extracting the agar. The conventional agar pro-duction process can be described in key stages of pre-treatment, extraction, fi ltration, concentration, and dehydration. In the current industrial practice of producing agar, large quantities of sodium hydroxide at elevated temperatures are used for several hours. Agar, being a viscous material, transfers energy poorly and large thermal gradients can result in sub-optimal conversions and result in loss of product. In this context, new extraction techniques have been tested in the last decade to accelerate the reaction based on microwave-assisted extraction (MAE).The MAE requires less energy and solvent than conven-tional processes while generating fewer wastes and can be designed as an alter-native eco-friendly agar extraction method.

14.4.1 Historical background Agar is a mixture of polysaccharides that occur in the cell matrix of marine red algae (Rhodophyta). The biological function of agar is to give a fl exible structure to the seaweeds, helping them stand the varying stresses of currents and wave motion (Craigie, 1990). Our ability to exploit the ‘inventions’ of nature for our own benefi t has led to the use of agar as a gelling agent in a large number of food and industrial applications. The Japanese were the fi rst to accidentally discover the original manufacturing method for extract-ing and purifying agar in 1658. The documented story described by Armis é n and Galatas (1987) tells that a Japanese offi cer arrived at a little inn where the innkeeper, Minoya Tarozaemon, offered him for dinner a traditional seaweed jelly dish, which had been prepared by cooking Gelidium with water. After dinner the surplus jelly was thrown outdoors by the innkeeper. The jelly froze during the night, then thawed and dried in the sun, leaving a dry, white residue. Tarozaemon found that when this was boiled in water and cooled, it produced a clearer jelly than was originally produced. This was named ‘kanten’, which literally translates as ‘frozen sky’. This name describes fi guratively the natural method of freeze-thawing which has been used since its discovery right up to the present day.

The use of agar in foods was widespread throughout the Far East, includ-ing Japan, China, Taiwan, Korea, the Philippines and Indonesia. In fact, the name agar-agar (nowadays called solely ‘agar’) is Malayan, where agar means jelly. In the Polynesian languages, the repeated word gives added emphasis; agar-agar is therefore translated as pure-jelly. Upon its later introduction into Europe, the Malayan term became attached to the Japanese seaweed extract (UNDP/FAO, 1990). As the fi rst phycocolloid used (200 years prior to alg-inates or carrageenans) agar was one of the fi rst food ingredients approved as GRAS (Generally Recognized As Safe) by the FDA (Food and Drug Administration) in 1972. It also passed all other toxicological, teratological and mutagenic tests (Armis é n, 1995). Popular culture associates agar con-sumption with longevity. In addition, because it consists of around 80%

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 14: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

488 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

fi ber, this phycocolloid is consumed to serve as an excellent intestinal regula-tor, playing an important role in the functional food market (Maeda et al. , 2005). Although the processed food industry is still the primary market for agar, there is an attractive market for the derivative products bacteriologi-cal agar and agarose, as microbiological and electrophoresis media respec-tively. Among the seaweed hydrocolloids agar, carrageenan and alginate, agar has the higher price, currently estimated at US$18/kg in 2009 (Bixler and Porse, 2011).

14.4.2 Sources of agarophytes The world agar industry mainly uses the following genera: Gelidium , har-vested from wild beds in Spain, Portugal, Morocco, Japan, Korea, Mexico, France, USA, China, Chile and South Africa; Gracilaria, the only agar source that is commercially cultivated at present in Indonesia and Chile and to a far lesser degree in Malaysia, Thailand and China; and Pterocladia , harvested from wild beds in the Azores (Portugal) and New Zealand (Fig. 14.1). The genera Gracilaria and Gelidium are the dominant industrial seaweeds for agar extraction. Gelidium species were the original materials used in Japan, but shortages during World War II led to the employment of Gracilaria species, to counteract the lack of Gelidium . About 9600 tons of agar (valued at US$ 173 million) were produced worldwide in 2009 (Fig. 14.1) and Gracilaria has become the preferred seaweed for the production of food grade agar. This is due to the success of its cultivation, the increase in its availability and subse-quent competitive prices (Bixler and Porse, 2011). The data obtained by the same authors show an increase of 69% in Gracilaria harvesting for the period of 1999 to 2009 and a decline of 73.3% of Gelidium in the same period. For further details see McHugh (2003).

14.4.3 Chemistry of agar and mechanism of gelation Agar is composed of a heterogeneous mixture of molecules, built on a disaccharide repeating unit of 3-linked β -D-galactopyranosyl and 4-linked 3,6-anhydro- α -L-galactopyranosyl residue. Substitution with sulfate hemi-esters, methyl ethers and/or pyruvate ketals can occur at various sites in the polysaccharide chain. The pattern of substitution depends on various aspects: environmental factors, such as hydrodynamic conditions, availability and quality of light and nutrients; physiological factors such reproductive stage and nutritional state; and the extraction and isolation conditions of agar. Agar polysaccharides isolated from Gracilaria are typically more sulfated than those obtained from Gelidium and Pterocladia , with the pattern of sul-fation dominated by the esterifi cation of C-6 of the linked galactose L-unit. This L-galactose 6-sulfated residue is synthesized in Gracilaria as a biologi-cal precursor of the 3,6-anhydro-L-galactose, and is enzymatically converted to the anhydrous form by sulphohydrolases (Murano, 1995). However, this enzymatic activity seems to be lower than that which occurs in Gelidium and

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 15: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 489

© Woodhead Publishing Limited, 2013

Pterocladia . A higher number of unfi nished 6-sulfated molecules are therefore found in agars from Gracilaria, producing none gelling or weak gel-forming polysaccharides. Thus, the physical properties of the resulting agar (gel strength, gelling and melting temperatures) are linked to their chemical struc-tures. The gelling ability of agars from most Gracilaria species can be con-siderably improved by adopting an alkali treatment before extraction, which increases the proportion of 3,6-anhydrogalactose. This reaction occurs when 6-sulfated-L-galactose units are present; by heating the polysaccharide in strong alkaline media, the 3-OH group can be ionized, producing an intramo-lecular nucleophilic displacement of the sulfate group in position 6. This reac-tion is highly specifi c and no other sulfate group is affected (Murano, 1995). Agar gelation occurs through a helical conformation of agar polysaccharides. These helices can be aggregated by hydrogen bonds. Consequently, the typical hysteresis of the thermoreversible order-disorder transition of agar can be highly perturbed by the presence of charged groups, which can interfere with intermolecular hydrogen bonding (Lahaye and Rochas, 1991). For further details on the agar gelation mechanism, see Armis é n and Galatas (2000).

One of the most remarkable features of agar gels is their thermorevers-ibility. Agar melts by heating to a temperature over 85 ° C, depending on the algal species, but becomes a gel again upon cooling. The gelling temperature is affected by the methoxyl groups, which vary depending on the algal species used (Guiseley, 1970). In particular, the extent of methoxylation of agar poly-mers from Gracilaria is signifi cantly higher than Gelidium and Pterocladia , and this difference is refl ected in their gelling temperatures, which are in the range of 40–42 ° C in Gracilaria species, compared to 34–36 ° C for Gelidiaceae .

14.4.4 Agar for food applications Traditionally three grades of agar with different gelling characteristics are recognized: food-grade, bacteriological agar and agarose (a neutral fraction of agar which has widespread use today for gel electrophoresis analysis). Bacteriological agars are usually prepared from Gelidium and Pterocladia , because agars from Gracilaria have gelling temperature above 40 ° C. Agarose is usually obtained from Gelidium , although some preparations of this more neutral molecule can be produced from certain select Gracilaria species (Murano, 1995).

Agar is employed as a vegetarian gelatin with high fi ber content, and is also used as a replacement in icings, glazes, processed cheeses and sweets. The use of agar in food applications is based on its ability to form gels, and the unique properties of these gels. Agar dissolves in boiling water and, when cooled, forms a thermoreversible, clear, colorless and odorless gel. In contrast to gelatin gels that melt around 37 ° C, agar gels do not melt until heated to 85 ° C or higher. The large difference between the gelling and melting tem-peratures (temperature hysteresis) is unusual, and unique to agar. In spite of agar having a very similar structure to carrageenan, it melts and gels at higher

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 16: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

490 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

temperatures, and many of its applications take advantage of this difference. As an example, agar is found to have specifi c uses in pastry fi llings and glazes, which can be applied before the pastry is baked without melting in the oven. The agar consumption for this segment of the market was 6050 tons dur-ing 2009 (Bixler and Porse, 2011). The same authors highlight the fact that although in processed meats carrageenan is the preferred water binder or tex-turing agent of choice, agar holds on to the gelatin replacement market in canned meats and aspics, with a market of 150 tons during 2009. The texture of agar in fruit jellies also helps it compete with kappa-carrageenan jellies, and the agar texture is preferred in Asia, particularly in Japan, where agar is a traditional ingredient which has been in use for hundreds of years. In the modern day it is one of the hydrocolloids that is available in many Asian grocery stores, and is sold as strips, in square form and more recently in tablet form. In western countries agar is sold through specialized stores as a ‘natural food and functional seaweed product’ with a market of 2000 tons in 2009 (Bixler and Porse, 2011).

Though species of Gracilaria generally produce agars with low gelling capacity or low gel strengths, they are considered the most important source of commercially valuable agar for the food industry, mainly due to the avail-ability of the biomass due to culturing, and the improved quality that can be obtained via the use of the alkali treatment. Furthermore, new dimensions in the application of Gracilaria agars are opening thanks to the discovery of its sugar-reactive property, an important effect by which an agar may increase the gel strength after the addition of sucrose (40–60%), increasing its com-mercial interest (Matsuhashi, 1990). However, since sugar consumption is directly related to diabetes and obesity, there is an increased interest in sugar-free products. This presents a different set of challenges, as low sugar content leads to diffi culties in gel formation of this kind of agar, with a decrease in texture, stability and uniformity. However, in response to this, a recent study demonstrated that by replacing sucrose with inulin-type fructans the strength of the agar gel may also increase (Kronberga et al. , 2011). Since oligosac-charides produce a lower caloric content (around 2 kcal/g) the authors stated that sugar may be replaced by inulin for those who like to consume agar jelly (where sugar is used) and have weight problems.

14.4.5 New insights into agar uses and potential markets About 90% of the agar produced is used in food applications, with the remain-ing 10% put to bacteriological and biotechnological uses. For further details on these different uses and the corresponding type of algae required, see Armis é n and Galatas (2000) and Bixler and Porse (2011). Though food appli-cations continue to grow, non-traditional uses of agar are continuously being tested. In the biomaterials fi eld, agar, either by itself or in blends with other biopolymers, appears to impart favorable properties to plastic fi lms, improv-ing resistance, clarity and increasing biodegradability (Madera-Santana

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 17: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 491

© Woodhead Publishing Limited, 2013

et al. , 2009, 2010; Madera-Santana et al. , 2011). Nevertheless, agar is more expensive than starch (commonly used for this application), which limits its large-scale use. Recently, the development of materials formed with magnetic particles inside an organic matrix have received great attention due to the possibility of inducing, by external magnetic fi elds, controlled changes in tem-perature and physical properties of the material. In biomedicine, such hybrid compounds with micro- or nanoparticles can be used as auxiliary elements for the diagnosis and treatment of diverse diseases. They also exhibit proper-ties that are desirable in the development of smart materials for biodegrad-able matrices. The application of alternating magnets to the electromagnetic fi elds could induce heating of the magnetic particles inside a biocompat-ible polymeric matrix, and the effects of such magnetic particles in agar are already being explored with promising results (Hsieh et al. , 2010; Chang et al. , 2011).

14.5 Conventional agar extraction methods

The production process of agar can be separated into certain key stages: pre-treatment, extraction, fi ltration, concentration and dehydration (Fig. 14.3). Details of each stage are given in Matsuhashi (1990, pp. 6–14), McHugh (2003, pp. 17–21) and Armis é n (2000, pp. 23–26).

14.5.1 Pre-treatments In order to obtain the purest possible extraction, seaweeds are fi rst washed to remove sand, salts, shells and other foreign matter. There are some differ-ences in the pre-treatment depending on the genus used. For Gelidium , this stage consists of a corrective treatment with a mild alkaline solution (usually sodium carbonate) to eliminate the pigment phycoerythrin and to macerate and prepare the seaweed for a better extraction. For Gracilaria , alkali treat-ment before extraction is performed to increase gel strength. The seaweeds are heated at 85–90 ° C in a sodium hydroxide solution, at concentrations ranging from 0.5% to 7% NaOH, for 1–2 hours. The concentration of the alkali, as well as temperature and time, must be adapted to each species of Gracilaria to obtain as much desulfation as possible while avoiding the yield losses that this process can cause (Freile-Pelegrin and Robledo, 1997; Freile-Pelegrin and Murano, 2005). After removal of the alkali, the seaweeds are washed with water and, occasionally, with very weak acid to neutralize any residual alkali.

14.5.2 Extraction and fi ltration Agar extraction necessarily involves cooking the seaweeds in an excess of water at boiling point. To promote a good extraction, careful addition of acid to adjust the pH to 6.3–6.5 is generally required. Extraction under pres-sure reduces processing time and increases the yield of agar. However, whilst both the pressure method and acid cooking are effective for agar extraction,

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 18: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

492 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

both of these conditions are potentially destructive to the extracted agar. Therefore optimum extraction conditions have to be established for each kind of seaweed. The agar dissolved in the water must be fi ltered to remove the residual seaweed, and the hot fi ltrate is cooled to form a gel. Depending on the agar quality sought, the gel may be treated with bleach (usually sodium hypochlorite) to reduce any color. Following such a treatment, the gel must be washed to remove the bleach, leaving a gel which contains about 1% agar. The remaining 99% is water and must be removed from the gel, either by a freeze-thaw process or by squeezing it out using pressure.

14.5.3 Concentration by freezing-thawing method The traditional technique adapted by Minoya Tarozaemon based on freezing and thawing is still in use to a small extent to produce ‘natural agar’ in the oriental craft industry (Matsuhashi, 1990). This technique begns with care-ful washing of Gelidium amansii, employing devices similar to those used to wash tea-leaves. In the past, the adjustment of pH during extraction was con-ducted with vinegar or sake but now diluted sulfuric acid is more commonly employed. The liquid extract is fi ltered while hot through cotton bags, poured into wooden trays and allowed to gel by cooling. Depending of the volume of gel, it can be cut into square bars or extruded to produce strips 25–40 cm long before the natural freeze-thaw process is used to dewater and concentrate the gel prior to drying. The seaweed extract, which normally contains 1–1.2% of agar during the process, is concentrated after thawing and straining (nor-mally by centrifugation) to contain 10 to 12% agar – a tenfold increase. The eluted water carries away oligomers, organic and inorganic salts, and proteins from the algae, including the phycoerythrins responsible for producing the red color of the Rhodophyceae family.

14.5.4 Concentration by syneresis method An alternative method to reduce water content in the gel is based on syneresis. The agar gel is placed between porous fi lter cloths and squeezed in a hydraulic press to remove water. This syneresis technique has spread rapidly all over the world due to the reduction in energy costs it facilitates. As a comparative example, the freezing method requires ice production of c.100 tons to produce one ton of agar, which requires far greater energy than the low energy consumption of the synere-sis method. Furthermore, agar purity increases in the syneresis method because a greater quantity of water and soluble impurities can be removed (Fig. 14.3).

14.5.5 Future trends in agar extraction: eco-friendly agar extraction as an alternative to conventional methods

Agar extraction is a relatively mature industry in terms of manufacturing methods and applications. Today, most processors are using press/synere-sis technology, although some still favor freezing/thawing technology or a

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 19: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 493

© Woodhead Publishing Limited, 2013

mixture of these approaches. While the basic processes may not have changed, improvements in presses and freezing equipment are being implemented to improve effi ciency and reduce energy requirements (Bixler and Porse, 2011). However, in the current industrial practice of agar extraction, large quantities of solvents are still used during bleaching, pre-treatment and during alkaline modifi cation. These steps must be carefully controlled to avoid the consider-able pollution generated by outfl ows of bleaching agents, alkaline residues and large quantities of ‘sodium agaropectinates’. Moreover, if an agar for

PretreatmentWashed and cleaned algae

GelidiumHeat with a mild Na2CO3 solution

to eliminate pigments and toimprove water penetration

GracilariaHeat with NaOH solution (0.5-

7%) to promote as muchdesulfation as possible and wash

Extraction

Filtration

Gelation

Freezing-thawing

Bleaching-Dialysis

Bleaching-Dialysis

Syneresis

Drying

Milling

Agar

Fig. 14.3 Flow diagram for agar production.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 20: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

494 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

industrial purposes can be obtained without the need for an alkaline treat-ment step, it may be more attractive from both an ecological and an eco-nomic point of view. This has been made possible for algae cultured through a special enzymatic process. This process is activated by darkness and salinity treatments to the biomass before being harvested (Yu and Peders é n, 1990; Rincones et al. , 1993; Freile-Pelegrin et al. , 2002). In this context, ‘green’ tech-nologies used to produce biomass, together with eco-friendly agar extraction methods, have arisen as alternatives to those used conventionally.

Photobleaching extraction process The chloride gas produced by the bleaching process, which is conducted to achieve the pure white color of agar, can adversely affect the health of work-ers (Warburton, 2005). Furthermore, the effl uents produced by bleaching constitute a pollution problem. In response to these problems, a novel agar photobleaching extraction process has recently been developed and patented by Jin et al. (2006) and Li et al. (2008). This process exploits the ‘green’ energy of sunlight and is based on the photochemical degradation of colored organic matters (CDOM). The authors claim that when solar radiation is absorbed by the CDOM in surface water, a rich variety of photochemical reactions will ensue. Such reactions are involved in energy transfer, electron transfer, and free radical reactions that lead to the cleavage of a variety of photoproducts, and to a reduction of average molecular mass. Furthermore, the enhanced mineralization produced helps to reduce dissolved inorganic compounds (DIC), such as carbon monoxide, carbon dioxide, and other forms of dis-solved organic carbon (DOC).

The CDOM photolysis is accompanied by a reduction in the absorption coeffi cients of the dissolved organic matter across the ultraviolet and visible spectral regions. This reduction in absorbance of light is termed ‘photobleach-ing’ (Gao and Zepp, 1998, cited in Li et al. , 2008). Gracilaria lemaneiformis and Gracilaria asiatica, growing as aquaculture bioremediation along the coasts of Liaodong Peninsula, China, were investigated in relation to agar production using the photobleaching extraction process (Li et al. , 2008). The duration of photobleaching was demonstrated to have a signifi cant impact on agar gel strength. To explain this response, the authors suggest that ‘agar with repeating sulfate-connected disaccharides underwent photolysis with the free radicals during the photobleaching process in water, which improved the gel strength by decreasing the sulfate content and increasing the 3,6-anhydro-L-galactose levels’. The above results indicate that the agar photobleaching extraction process is a feasible method for Gracilaria species and has good potential as an application of green technology.

Microwave-assisted extraction In the last decade, microwave-assisted extraction (MAE) has been success-fully applied to various fi elds of analytical chemistry. This technique involves the use of microwave energy to heat solvents in contact with a sample. The

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 21: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 495

© Woodhead Publishing Limited, 2013

algal matrix is highly susceptible to microwave irradiation, owing to the high natural moisture content. Rapid internal heating of these structures brings about effective cell rupture, releasing the analytes into the cold solvent (Mandal et al. , 2007). The main advantages of the proposed procedure are the reduced consumption of solvents (in comparison to solvent consumption of traditional methods), the lower level of energy required and the reduced extraction time.

Recently, Sousa et al. (2010) reported the fi rst extraction of an agar using MAE from Gracilaria vermiculophylla, from an integrated multitrophic aqua-culture (IMTA) system. The authors obtained higher yields and reproducibil-ity, as well as higher gel strength, in comparison to conventional extraction methods. The MAE approach supports sustainable development, as it requires less energy and solvent than conventional processes, whilst generating fewer waste products. This research suggests the feasibility of using MAE as a ‘green’ technology for the production of superior quality agar gels.

In the so-called integrated polyculture systems, recently grouped under the term IMTA systems, the wastes generated during the growth of a species are ‘recycled’ to become ‘food’ for another, so that different aquatic resources are interacting positively with each other (Robledo and Freile-Pelegrin, 2011). The implementation of this concept in the context of fi sh farming is to improve the utilization of marine resources, increase the profi tability of these activities and ensure the sustainability of aquaculture. In this context sea-weeds play a critical role, as they are primary producers capable of converting dissolved substances that have been excreted by organisms of other trophic levels into additional crops.

In addition to its biofi ltration effi cacy, the economic value of the biomass should be considered when choosing the seaweed species to work with in IMTA systems. Gracilaria is one of the most cultivated and valuable seaweeds worldwide. Adopting the IMTA approach with this genus has already pro-duced good examples of signifi cant revenues for the fi sh aquaculture industry (Neori et al. , 2000; Chopin et al. , 2001; Abreu et al. , 2011). Green technology for the large-scale production of important agarophytes as IMTA systems, together with the use of eco-friendly agar extraction methods, are key to the future of the agar industry.

14.6 Carrageenan

Carrageenan is a phycocolloid, extracted from different genera of red sea-weeds, where this substance plays a structural function. It is a strongly ionic polysaccharide, composed of galactose with different degree and pattern of sulfates distributed in the polymeric chain, which impart characteristic solu-bility properties. Some carrageenans are soluble in cold water, with only vis-cosifi ng properties, whereas others are soluble only in hot water and have the ability to form a thermoreversible gel, with potassium or calcium ions. It is widely used in the food and pharmaceutical industries. The extraction

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 22: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

496 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

process of carrageenans from seaweeds is divided into two process lines based on the purity of the product obtained. In the fi rst method, it is necessary to dissolve the polysaccharide in the solution , then it is fi ltered to remove solid particles, and the carrageenans are recovered from the solution and impurities by precipitation with an organic solvent or with potassium salts. In the second method, the carrageenan is actually not extracted – seaweed is treated usually with alkaline solution, then soluble impurities are removed, leaving mostly carrageenan and cellulose, which are dried and milled. Although with this second process the carrageenan is more impure, it is cheaper, making it more attractive and favoring the development of new uses. Recently the market for carrageenans is growing, making it essential to search for new raw materials and improved technologies with less impact on the environment.

14.6.1 Historical background Carrageenan is the generic name of a family of natural, water soluble poly-saccharides, isolated from several kinds of red seaweeds. Carrageenan, com-posed of sulfated galactans, have both gel-forming abilities and viscosifying properties. In addition to forming thermoreversible gels, they are labile at high temperatures in acidic conditions. Historical use of carrageenan can be tracked back in Europe, where for about 600 years a substance obtained by cooking certain red seaweeds has been used as a thickening and stabilizing agent in foods. In Europe and North America, a kind of fl an (blancmange) was made by cooking red seaweeds as Chondrus crispus or Gigartina stellata in milk (van de Velde and de Ruiter, 2002). The name ‘carragee’ seems to have been introduced around 1829, derived from the Irish word, carraigeen, mean-ing ‘rock moss’ in reference to the seaweed C. crispus or ‘Irish moss’ (Mitchell and Guiry, 1983). The name carrageenin was fi rst used by Stanford in 1862 to refer to the gelatinous water extract from C. crispus (Tseng, 1946). Nowadays, the term ‘carrageenan’has become accepted, in agreement with the use of the -an suffi x, within the polysaccharide nomenclature (Stanley, 1987).

Formerly, the carrageenan process was based on the direct use of sun-bleached seaweeds. The fi rst procedure for obtaining carrageenan was developed by Schmidt in the USA in 1844 (Armis é n, 2000). Commercial car-rageenan production was then initiated in Maine, USA (1937), where C. cris-pus from Maine and the Maritime Provinces Canada, was used as the main raw material. It was known that carrageenan was a heterogeneous compound, made up of galactose and ester sulfate, but very little was understood about its structure. In 1953, Smith and Cook, using crude carrageenan from C. cris-pus , were able to separate two fractions based on their solubility in potassium chloride solution. One fraction precipitated selectively by potassium ions ( Kappa ), while the other fraction remained in the solution, as it was non-sensitive to potassium ions ( Lambda ).

The existence in carrageenans of more than two fractions within a C. crispus extract was demonstrated by Pernas et al. (1967). They carried out a

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 23: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 497

© Woodhead Publishing Limited, 2013

fractional precipitation with KCl and found not only kappa and lambda frac-tions, but instead a continuous spectrum of carrageenans, each with different chemical compositions and properties. Further studies, derived from the red seaweed Eucheuma spinosum, elucidated a third type of carrageenan; the iota-carrageenan (Rees, 1969). Many carrageenan types have now been described (mu, kappa, nu, iota, theta and lambda among others), each of them with specifi c physicochemical properties, differing in amounts of 3,6-anhydro-D-galactose, and degree and pattern of sulfation (Painter, 1983; Craigie, 1990). Despite the wide carrageenan variety found in nature, from a commercial point of view there are three main commercial carrageenans: kappa, iota and lambda. They are differentiated by their sensitivity to potassium ions, and their uses are related to their ability to form viscous solutions or gels (Table 14.1).

14.6.2 Sources of carrageenophytes Chondrus crispus, commonly known as ‘Irish moss’, was the original raw material for carrageenan production. However, as demand increased and new applications appeared, it was necessary to fi nd a new supply of raw materials. Since different species produce different types of carrageenan, new seaweed species were incorporated into carrageenan manufacture (Table 14.2). Thus the availability of particular seaweed species determines their commercial use (McHugh, 2003).

It is unusual for one seaweed to be reported as containing a single car-rageenan type, as seaweeds generally contain molecules of the hybrid type, in which repeating units of different carrageenans exist in the same molecule (i.e. kappa-iota hybrids) (Usov et al. , 1980; Usov, 1998; Craigie, 1990; van de Velde, 2008). In seaweeds which are members of Gigartinaceae, carrageen-ans of the kappa family (hybrids kappa-iota) are produced by gametophytes, whereas hybrids of the lambda family (lambda, xi and pi) are produced by

Table 14.1 Main commercial carrageenans and their functional properties

Carrageenan type General properties

Kappa Form strong and rigid gel with potassium salts. Brittle gels with calcium salts. Shown syneresis. Synergy with locust bean gum

Iota Form strong gels with calcium salts. Elastic and clear gels. Gel is freeze-thaw stable. Gels without syneresis.

Lambda Non gelling with potassium ions, form high viscosity solutions.

Soluble in concentrated salt solutions.

Source: Modifi ed from Moirano, 1977.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 24: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

498 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

tetrasporophytes (McCandless et al. , 1973; Craigie, 1990). In contrast, the genus Eucheuma produces different types of carrageenan depending of the species, with no differences between life cycles (Craigie, 1990) (Table 14.2). Nowadays the carrageenan industry uses a wide number of seaweed spe-cies; all of these belong to seven Rodophyta families: Gigartinaceae, Solieraceae, Rhabdoniaceae, Hypnaceae, Phyllophoraceae, Furcellariaceae and Rhodophyllidaceae (Dawes et al. , 1977; Deslandes et al. , 1985).

C. crispus continues to be used in the industry, but only in limited quanti-ties. It is mainly harvested from natural stocks in the USA (coast of Maine and Massachusetts), Canada (Nova Scotia and Prince Edward Island) and France. In the mid 1960s, there was an increased interest in Eucheuma species from the Philippines and Indonesia, such as Kappaphycus alvarezii (formerly E. cottonnii ) and E. denticulatum (formerly E. spinosum ). These were fi rst har-vested from natural stocks, but by the early 1970s Eucheuma farming was being developed in both countries. Cultivation also spread to Tanzania (Zanzibar), Vietnam and some of the Pacifi c Islands, such as those of Kiribati. Wild Betaphycus gelatinum (formerly E. gelatinae ) is mainly harvested in China, Taiwan Province of China and the Philippines, and it is both harvested and cultivated on Hainan Island (McHugh, 2003) (Fig. 14.1). Several Gigartina species from natural stocks are harvested in South America, particularly in Chile, Argentina, Peru and Mexico (Fig. 14.1, Table 14.3).

In the last decade, seaweed production increased by 17%, exceeding 202 000 dried tons per year, and valued at over 70 million USD. Recent data

Table 14.2 Main seaweeds used in carrageenan production and carrageenan type produced

Seaweed Life stage Carrageenan type

Chondrus crispus 1 Gametophyte Kappa/iota ( κ / ι ) Tetrasporic Lambda ( λ )

Chondracanthus canaliculatus 2,3

Gametophyte κ / ι Tetrasporic λ

Mastocarpus stellatus 1 Gametophyte κ / ι Tetrasporic (absent phase)

Gigartina skottsbergii 4 Gametophyte κ / ι Tetrasporic λ

Sarcothalia crispata 5 Gametophyte κ / ι Tetrasporic Deviant λ

Furcellaria lumbricalis 6 Kappa/beta ( κ / β ) Kappaphycus alvarezii 1 Mainly kappa ( κ / ι ) Eucheuma denticulatum 7 Mainly ι Betaphycus gelatinum 8 Mainly beta ( β ) Hypnea 9 κ / ι

1 Bellion et al. , 1983; 2 Penman and Rees, 1973; 3 McCandless et al. , 1983; 4 Matulewicz et al. , 1989; 5 Ayal and Matsuhiro, 1987; 6 Usov and Arkhipova, 1981; 7 Usov and Shashkov, 1985; 8 Greer and Yaphe, 1984; 9 McCandless, 1978, 1981.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 25: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 499

© Woodhead Publishing Limited, 2013

has shown that K. alvarezii accounts for roughly 80% of the total production. By 2009, carrageenans had the highest production level among the phycocol-loids (50 000 tons). Despite the lower unitary price, carrageenans account for roughly 50% of phycocolloids sales (Fig. 14.1). The current price of car-rageenans (2012) is related, among other characteristics, to the purity of the product; regular products are about US$6–15/kg. Table 14.3 shows the dif-ferent carrageenan sources used in carrageenan manufacture (Stanley, 1987; McHugh, 2003, 2006).

14.6.3 Chemistry of carrageenan Carrageenan, together with agar and furcellaran (formerly Danish agar), belong to the family of linear polysaccharides derived from red seaweeds called sulfated galactans. Instead of some structural particularities, they are broadly differentiated from each other by their sulfation degree, where agar yields 3–4% sulfate, furcellaran yields 8 to 19% (actually belonging to the carrageenan family), and carrageenan more than 20% (Moirano, 1977). The carrageenan molecule has a repeating structure of alternating 1,3-linked

Table 14.3 Carrageenan sources and origin of raw materials used in carrageenan manufacture

Seaweed species Old name Source Country

Chondrus crispus Natural stocks United States, Canada, France, Spain, Portugal

Furcellaria spp Natural stocks Denmark, Russia Mastocarpus

stellatus Gigartina stellata Natural stocks Spain, Portugal,

Morocco. Kappaphycus

alvarezii Eucheuma

cottonii Mostly farming Philippines, Indonesia,

Tanzania, Vietnam, Kiribati Islands Eucheuma

denticulatum Eucheuma

spinosum Mostly farming

Betaphycus gelatinum

Eucheuma gelatinae

Farming and Natural stocks

Hainan Island, Philippines, China and Taiwan

Gigartina skottsbergii

Natural stocks Chile, Argentina

Sarcothalia crispata

Iridaea ciliata Natural stocks Chile

Mazzaella laminaroides

Iridaea laminaroides

Natural stocks Chile

Hypnea musciformis

Natural stocks Brazil

Chondracanthus canaliculatus

Gigartina canaliculata

Natural stocks Mexico

Sources : Stanley, 1987 and McHugh, 2003, 2006.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 26: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

500 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

β -D-galactopyranosyl and 1,4-linked α -D-galactopyranosyl units, where the 3-linked unit can be unsulfated, 2-sulfated or 4-sulfated. The 4-linked unit can occur as 2-sulfate, 6-sulfate, 2,6-sulfate, 3,6-anhydride or 3,6-anhydride 2-sulfate (Stanley, 1987, Craigie, 1990).

There are many individual carrageenan types, each one named in Greek let-ters, following the originally proposed nomenclature (Smith and Cook, 1953). The carrageenans are then grouped into three main families: the Kappa fam-ily, including kappa ( κ ) and iota ( ι ) carrageenans; the Beta family including beta ( β ) and omega ( ω ), and the Lambda family which include theta ( θ ) and pi ( π ) (Table 14.4). In each of these families there are different related pre-cursor structures. For more information on this classifi cation, see Greer and Yaphe (1984) and Craigie (1990). Because of the large number of carrageenan structures defi ned at present, the carrageenan nomenclature is becoming more confusing. To reverse this, Knutsen et al. (1994), proposed a more systematic nomenclature for carrageenan and agars, based on the IUPAC (International Union of Pure and Applied Chemistry) nomenclature. However, for the pur-pose of this work we will continue using the Greek prefi x letters. The differ-ent carrageenan structures differ in the 3,6-anhydrogalactose and ester sulfate contents. Variations in these components infl uence hydration, gel strength and texture, melting and setting temperatures, syneresis and synergism. These differences are controlled and created by seaweed selection, processing and blending of different extracts (Imeson et al. , 1977, 2000).

14.6.4 Carrageenan for food applications Traditionally, the main applications of carrageenan are in the food industry. In order to explore why carrageenan is so well suited to these applications, we will fi rst briefl y describe the properties of the main commercial types. In the fi elds of food, drugs and cosmetics, these are generally used at concentrations as low as 0.01 to 1.0% (Hansen, 1987). Kappa and iota carrageenan have the ability to form gels with potassium and calcium ions. Kappa carrageenan forms the strongest gel, while gels of iota are more elastic. The binding of cat-ions in carrageenans reduces the effective charge density of the helical chains, subsequently promoting helix aggregation and the formation of a three- dimensional gel structure (Williams, 2009). Kappa reacts with potassium ions to form strong, rigid gels, while the reaction with calcium ions produces gels that are brittle (Table 14.1). Kappa gels can be set with as little as 0.5% in water and 0.2% in milk (Imeson, 2000). Gels with only kappa carrageenan can suffer syneresis (water bleeding), but this problem can be solved by using appropriate blends of kappa with iota or lambda carrageenan, which reduce the rigidity of the gel, improving the water retention ability (Imeson, 2000).

Another way to eliminate the syneresis of kappa gels is by making blends with different gums, such as locust bean gum or konjac fl our. Such gums pro-duce a synergistic effect, improving the elasticity and the gel strength. This, in turn, allows a reduction in the amount of kappa carrageenan needed to

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 27: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 501

© Woodhead Publishing Limited, 2013

maintain the required gel strength, rendering the gels more elastic, clear and free of syneresis (Williams, 2009). Iota carrageenan has the ability to form stronger gels with calcium ions than potassium; the iota gels are elastic and free of syneresis. These iota gels also exhibit thixotropic fl ow behavior, mean-ing that the gel can be stirred and will fl ow like a thick liquid (syrup), before, in repose again, gradually re-forming back into a gel. The iota carrageenan has vast uses in frozen desserts, where it gives a smooth, creamier texture to the fi nal product. Lambda carrageenan is a very soluble polysaccharide in cold or hot solutions and is soluble with all salts at any concentration, with low concentrations imparting high viscosity to solutions.

Until the late 1970s, carrageenan use in food products was mainly confi ned to milk products, due to the unique ability of carrageenan to interact with the casein in milk. A very low carrageenan concentration can keep milk solids in suspension and stabilize them. This prevents whey separation in cheese prod-ucts and enhances the formation of fi ne crystals in milk ice cream, producing a creamier texture in the mouth. Such properties mean these carrageenans have been used widely in milk product applications, including in cheese produc-tion, cocoa suspensions, chocolate milk products and milk gel fl ans, amongst others. In this line of applications, kappa and lambda carrageenan obtained from Gigartinales give excellent results.

Another area that has been positively drawing on carrageenan production since the early 1980s is the meat industry, where carrageenans are now exten-sively used, particularly those obtained from Eucheuma species. The great ability of kappa carrageenan to hold water makes this product very suitable as a replacement for fat in meat products, where it improves the fi nal texture. Kappa carrageenans are employed in the production of ham, lean ham and hamburgers, processed meat, reconstituted seafood and poultry products. To obtain the optimum results, the carrageenans are commonly blended with others gums, such as locust bean gum or konjac fl our, improving the charac-teristics of the product and making an important reduction to the amount of carrageenan needed. As a part of the commercialization of carrageenan, producers now make gum blends which are appropriately tailored for the spe-cifi c applications required.

Carrageenans also have important uses in water gel applications, such as gummy candies, fruit gels, fruit juices and marmalades, for example, as well as in toothpaste, bakery products and slow release capsules (Imeson, 2000; Bixler and Porse, 2011).

14.6.5 New insights for carrageenan uses and potential markets

Following the initial success of commercial carrageenan production for food product applications, diverse new uses are continuing to emerge across a range of areas, including water applications, candies, freshener gels, cosmet-ics and in the meat industry, for example. Nowadays the food uses account for 90% of commercially produced carrageenan (Bixler and Porse, 2011),

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 28: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

© Woodhead Publishing Limited, 2013

Tab

le 1

4.4

Idea

lized

mol

ecul

ar s

truc

ture

s of

diff

eren

t ca

rrag

eena

n fa

mili

es

Pre

curs

ors

Idea

lized

ter

min

al s

truc

ture

s

Bet

a ca

rrag

eena

n fa

mily

HO

CH

2OH

O

O HO

O

- O3S

O

H2C

OH

HO

O

G

amm

a

HO

CH

2OH

OS

O3

O

O

O

HO

HO

O- O

3SO

H2C

P

si

HO O

CH

2OH

HOO

O

O

O OH

B

eta

HO

CH

2OH

HOO

OO

OO

OS

O- 3

O

meg

a

Kap

pa c

arra

geen

an f

amily

CH

2OH

O

OO

O

OH

HO

HO

- O3S

O- O

3SO

H2C

M

ù

CH

2OH

HO

OH

O

O

O

OO

- O3S

O

K

appa

CH

2OH

O

OO

O

O

HO

HO

- O3S

O- O

3SO

SO

3-H

2C

N

ù

CH

2OH

HOO

OO

OO

- O3S

O

- O3S

O

Io

ta

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 29: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

© Woodhead Publishing Limited, 2013

Lam

bda

carr

agee

nan

fam

ily

CH

2OH

O

O

O

O

HO

HO

- O3S

O

OS

O3-

- O3S

O

H2C

L

ambd

a

CH

2OH

O

OO

O

HO

HO

HO

OS

O3-

- O3S

O

H2C

D

elta

CH

2OH

O

O

O

OHO

HO

H2C

OH

- O3S

O

OS

O- 3

X

i

CH

2OH

HO O

O

O

O

O

- O3S

OO

SO

3-

The

ta

CH

2OH

HO

HO

O

OO

OO

OS

O3-

A

lfa

Sou

rce :

Mod

ifi ed

fro

m G

reer

and

Yap

he, 1

984.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 30: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

504 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

with the dairy and meat industries the main application sectors (Table 14.5). In the last decade a production increase of 18% (from 42 000 to 50 000 m tons) was observed in the carrageenan market, mostly refl ected in meat and water gel applications (Bixler, 1996; Bixler and Porse, 2011). It is diffi cult to predict how future substantial changes could alter the carrageenan market. However, emerging economies such as China and Brazil are already having an important impact on the raw materials; increased use of these raw products is refl ected in the current seaweed and carrageenan prices, in turn affecting the expansion of the carrageenan market.

Further increases in carrageenan use and new applications can be expected as understanding of their value as bioactive compounds develops. This bio-activity is associated with the sulfate content, and some novel commercial products are using it for its antiviral properties. Carraguard™, for example, is used as a sexual lubricant and microbicide, and it is further suspected that it may have a protective effect against the human papilloma viruses (HPV), her-pes simplex viruses (HSV) and against human immunodefi ciency virus (HIV). Despite the presence in the market of some commercial products, more trials must be conducted with this kind of application before the full potential in this area can be assessed.

14.7 Conventional carrageenan extraction methods

Carrageenan is present in some types of red seaweeds as a water soluble anionic polysaccharide. In the plant, it is mostly found immersed in the cell wall and cell matrix, functioning as a structural polysaccharide and contributing to the rigidity and fl exibility of the plant (Lobban and Harrison, 1994). In the cell wall, carrageenans have strong interactions with proteins, pigments, minerals and others polysaccharides, such as cellulose and hemicelluloses, alongside various other seaweed components.

In order to use the functional properties of the carrageenans as a prod-uct, there are two main lines of processing: a) refi ned carrageenan, which involves extraction in aqueous solution, fi ltration and precipitation and b) semi-refi ned carrageenan, where the carrageenan is retained in the seaweed while other seaweed components are eliminated (Schweiger et al. , 1992).

Table 14.5 Carrageenan use (%) by market segment

Market segment/year 1996 1999 2009

Meat 31 24 37 Dairy 44 29 28 Water gels 15 11 17 Toothpaste 8 4 4 Others 4 5 4

Source : Bixler, 2006 and Bixler and Porse, 2011.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 31: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 505

© Woodhead Publishing Limited, 2013

14.7.1 Refi ned carrageenan

Alcohol process This is the fi rst commercial process used. The objective is to get the carra-geenan free of the other seaweed components, before further separating the carrageenan from the cell wall materials, solubilizing it in an aqueous solu-tion. Firstly, in order to remove sand, salts, shells and other foreign matter, the dry seaweeds are washed with running water. The extraction is then car-ried out with a mild alkaline solution (sodium bicarbonate) at pH 8 to 9, at a ratio of 1:50 (solid:liquid) which is boiled for two hours. When the carra-geenan is in solution, the cellulose and other insoluble material are discarded via different clarifi cation processes, most commonly by fi ltration using a fi lter aid on a pressure fi lter (Fig. 14.4).

To recover the carrageenan from the solution, and to reduce the alcohol needed to produce a precipitate, the clear solution is vacuum evaporated to approximately a third of the original volume. The precipitation is car-ried via an organic solvent, commonly isopropyl alcohol (proportion 2:1, solvent:extract), and the carrageenan is precipitated whilst the water and soluble impurities remain in solution. This process produces the so-called ‘refi ned carrageenan’. Already successfully applied to the processing of C. crispus and different Gigartina species, this methodology can be used to

Drum drying

Drying

Drying

Alcohol recoveryby distillation

Alcohol precipitationethanol or isopropanol

Concentrationby vacuum evaporation

Concentrationby vacuum evaporation

KCl precipitation

Milling

Blending

DewateringBy freeze-thaw

or pressing

ExtractionBoiling with NaHCO3

pH 8–9

Dry seaweeds

Alkaline treatmentKOH ≥5% 80°C

Neutralization

ExtractionBoiling with NaHCO3

pH 8–9

Washing

FiltrationFiltration

PurifyingEthanol: Water

Mixture

Crude carrageenan

Milling

a b c dBlending

Kappa, iota or lambda Kappa, iota or lambda Kappa, iota or lambda Kappa, carrageenan

Milling

Blending

Milling

Blending

Fig. 14.4 Flow chart for refi ned carrageenan production, where the three left options (a, b and c) can be used to process any kind of seaweeds (Gigartinales species) while the KCl (d) option is only for kappa carrageenan-producing species (i.e. Kappaphycus

and gametophytes from Gigartinales).

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 32: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

506 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

process any seaweed. Importantly, this means it can be used to produce any kind of carrageenan (Fig. 14.4c). Until now this methodology is the only alternative for obtaining the highly soluble lambda carrageenan. The disadvantage of this method is the high cost involved in the distillation of large volumes of alcohol and the purchase of the necessary explosion-proof equipment.

Potassium chloride process This is a variant of the alcohol process which also involves the carrageenan ini-tially being in a solution. However, the difference is in the precipitation method used; instead of using alcohol, KCl to 1% (w/v) is added, and a gel is formed by lowering the temperature on a counter current pipe. Dewatering is achieved via a freeze-thaw process or by pressing the gel, as in the agar process. While this process is cheaper than the alcohol-based method, it is exclusive to the produc-tion of kappa carrageenan. This is, however, an appropriate methodology for processing gametophytes of the Gigartinaceae family and such kappa carra-geenan-bearing seaweed as Kappaphycus alvarezii and other Eucheuma species (Fig. 14.4d).

Drum drying process A third alternative for producing refi ned carrageenan differs from the other methods in that the carrageenan is recovered directly from the aqueous solu-tion. Instead of precipitation, the water is removed by evaporation. This can be accomplished through the use of a steam heated, single or double drum dryer. The best performance is achieved in a vacuum chamber, which speeds up the process and prevents excessive thermal breakdown of the carra-geenan molecule. The carrageenan is then recovered as fl akes which contain some soluble impurities (Fig. 14.4a). In order to equal the quality produced by the alcohol precipitation method, these impurities need to be removed, which can be achieved by solubilization with an alcohol: water mixture ( ≥ 60:40). This process is cheaper and uses much less alcohol than the aforementioned alcohol precipitation method. However, the economy of the process is similarly infl uenced by the alcohol recovery effi ciency. This process can be applied to the production of any carrageenan type (Fig. 14.4b).

14.7.2 Alternative carrageenan extraction methods After the success in Eucheuma farming in Philippines, further developments led to the production of E. cottonii fl our, which was applied in the manu-facture of canned pet food. By the early 1980s, the quality of the fl our had improved to a level that allowed its use in food applications, especially in areas where clarity was not a requisite, as in the meat industry, for example. The products used for such applications, known as Semi-refi ned Carrageenan

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 33: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 507

© Woodhead Publishing Limited, 2013

(SRC), Philippines Natural Grade (PNG) or Philippines Eucheuma Seaweed (PES), were subsequently accepted by the FDA in the USA.

14.7.3 Semi-refi ned carrageenan In this process the carrageenan is never actually extracted from the seaweed. Instead, it is retained in the seaweed, but all other components (including soluble proteins, minerals, pigments and fats) are, as far as possible, elimi-nated from the seaweed. The process for producing this kind of product involves obtaining fresh or dried seaweed, such as Kappaphycus alvarezii or Eucheuma denticulatum , which is then subjected to an alkali treatment with a hot alkali solution: KOH or Ca(OH) 2 at ≥ 5% in seawater at 70–80 ° C for over 1 h. After this treatment, some of the sulfate groups are released, and 3,6-anhydro-galactose is formed, improving the gel strength of the product. The hot alkali and subsequent washing removes residual minerals, proteins and fats, leaving the carrageenan and some residual cellulose in the seaweeds. The alkali-treated seaweed is chopped into small pieces, bleached, dried and milled. Sometimes the dried product is chopped into pieces but not milled, and is sold as a raw material for the production of refi ned carrageenan. This

(a)

Eucheuma species Gigartina species

Dryseaweeds

Dryseaweeds

Alkaline treatmentKOH ≥5% 70–80°C

Alkaline treatmentEthanol: Water KOH ≥5%

70–80°C

Ethanol washing Ethanol recoveryby distillation

Drying

Milling

Blending

Semi refined kappa IIcarrageenan

Semi refined kappacarrageenan

(alkali treated cottonii)(ATC)

Neutralization

Sun drying

Milling

Blending

(b)

Fig. 14.5 Flow chart of semi-refi ned carrageenan production, where the carrageenan actually is not extracted from the seaweed. Usually the seaweeds are alkali treated in order to increase the gel strength (a) in alkaline water solution for Eucheuma species or (b) for Gigartina in alkaline alcohol media; the fi nal product in all cases contains

seaweed particles.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 34: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

508 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

product is called alkali-treated cottonii (ATC), alkali-treated cottonii chips (ATCC), or even simply cottonii chips (Fig. 14.5a) (McHugh, 2003).

14.7.4 Mixed carrageenan extraction methods A hybrid process has been developed in which raw materials are treated in the same manner as in the semi-refi ned process, retaining carrageenan in the seaweed, but instead of using the water alkaline solution, the alkali treat-ment is carried out in an alcohol slurry (Fromholt, 1998). The proportion of alcohol in the alcohol:water mixture used for the treatment should be high enough to inhibit carrageenan dissolution. This proportion is usually above 60:40 at 80 ° C at high alkali concentration (commonly KOH ≥ 5%), which is usually suffi cient to dissolve such impurities as pigments, fats, minerals and other components. Although this process is more expensive than the semi-refi ned process, the alcohol used can be recovered effi ciently (Fig. 14.5b). The advantage of this process is that it can potentially be used to process any seaweed.

The other processing line commonly used in carrageenan extraction is called selective extraction. In this process, the carrageenans are selectively extracted by inhibiting the solubility of one type of carrageenan and increas-ing the solubility of others. In mixtures of kappa–lambda species, kappa carrageenan is kept in the seaweed using an optimum KCl concentration and low temperature (20–30 ° C) treatment (Fig. 14.6). This allows the extrac-tion of lambda carrageenan and/or precursors as mu and nu carrageenans (Stancioff, 1965). Soluble lambda carrageenan and precursors are sepa-rated and preci pitated with alcohol (Fig. 14.6a), while kappa is processed as semi-refi ned via drying and milling (Fig. 14.6b). Alternatively, the kappa carrageenan can be extracted into a solution by increasing the temperature; after fi ltration, it is recovered with alcohol or KCl as refi ned carrageenan (Fig. 14.6c). This process can be modifi ed by applying alkali treatment to raw seaweeds.

14.7.5 Future trends in carrageenan extraction The development and employment of innovative MAE techniques can have a favorable effect on process effi ciency to reduce the cost of algal polysaccha-ride extraction. The microwave method allows selective and localized heating of materials without requiring the application of excessive energy. This tech-nology involves the use of non-refractive materials and clear transport pipes, which allow the heating process to be successfully achieved (Kluck, 1970). Another advantage of this methodology is that less heat damage is done to the carrageenan molecule, as the heat is applied over a shorter period of time (Scott, 1984) In addition, smaller amounts of water and alkali are needed for this method, due to the improved effi ciency, leading to a reduction in the environmental impact.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 35: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 509

© Woodhead Publishing Limited, 2013

14.8 Conclusions

The search for new functional ingredients from natural sources is one of the most important challenges in food science and technology. It is driven by a social demand for new functional foods with scientifi cally demonstrated health properties. Marine algae are well known natural sources of gums, such as alginate, agar and carrageenan. Once their usefulness in the food, pharma-ceutical and other industries has been well demonstrated, it will be necessary to overcome the scarcity and poor quality of some raw materials. This may be achieved through the development on an industrial scale of the so-called integrated polyculture systems, and improved processing technology for the production and purifi cation by environment-friendly extraction processes in a fast, cost-effective and non-aggressive way.

14.9 References ABREU, MH, PEREIRA, R, YARISH, CH, BUSCHMANN, A and SOUSA-PINTO, I (2011), ‘IMTA

with Gracilaria vermiculophylla : productivity and nutrient removal performance of the seaweed in a land-based pilot scale system’, Aquaculture , vol. 312, pp. 77–87.

SeaweedsDry

Water extraction20°C, KCl

Seaweedresidue

CentrifugationSeaweedresidue

ExtractionBoiling NaHCO3

pH 8–9

Drying Liquid

Milling Filtration Filtration

Ethanolprecipitation

≥70%

Ethanol or KCl precipitation

Drying Drying

Milling Milling

(a)

(b)

(c)

Kappa Carrageenan LambdaCarrageenan

Kappa Carrageenan

14.6 Flow chart of selective carrageenan production, suitable for species like Chondrus and Gigartina where lambda carrageenan is selectively extracted at low temperature in the presence of potassium salts (a) keeping the insoluble kappa carrageenan in the seaweed, then recovering directly from the seaweed residue (b), or by further extraction

and precipitation procedure (c).

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 36: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

510 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

ALIREZA-RAZAVI, A, KHODADADI, A, BAGHER-ESLAMI, M, ESHRAGHI, S and MIRSHAFIEY, A (2008), ‘Therapeutic effect of sodium alginate in experimental chronic ulcerative coli-tis’, Iranian Journal of Allergy, Asthma and Immunology , vol. 7, no. 1, pp. 13–18.

ARMIS É N, R (1995), ‘World-wide use and importance of Gracilaria ’, Journal of Applied Phycology , vol. 7, no. 3, pp. 231–243.

ARMIS É N, AR (2000), ‘Ficocoloides. Polisac á ridos de las algas marinas’, ed., Madrid (Espa ñ a).

ARMIS É N, R and GALATAS, F (1987), ‘Production, properties and uses of agar’, In: DJ McHugh (ed), Production and Utilization of Products from Commercial Seaweeds , FAO Fisheries Technical Papers 288, Rome.

ARMISEN, R and GALATAS, F (2000), ‘Agar’, In: G Phillips and P Williams (eds), Handbook of Hydrocolloids , Boca Raton, Florida, CRC.

ARVIZU-HIGUERA, DL, HERN Á NDEZ-CARMONA, G and RODR Í GUEZ-MONTESINOS, YE (1995), ‘Batch and continuous fl ow system during the acid pre-extraction stage in the alg-inate extraction process’, Ciencias Marinas , vol. 21, no. 1, pp. 25–37.

ARVIZU-HIGUERA, DL, HERN Á NDEZ-CARMONA, G and RODR Í GUEZ-MONTESINOS, YE (1996), ‘Effect of temperature and extraction time on the process to obtain alginate from Macrocystis pyrifera ’, Ciencias Marinas , vol. 22, no. 4, pp. 511–521.

ARVIZU-HIGUERA, DL, HERN Á NDEZ-CARMONA, G and RODR Í GUEZ-MONTESINOS, YE (1997), ‘Effect of the type of precipitation on the process to obtain sodium alginate: cal-cium alginate method and alginic acid method’, Ciencias Marinas , vol. 23, no. 2, pp. 195–207.

ARVIZU-HIGUERA, DL, HERN Á NDEZ-CARMONA, G and RODR Í GUEZ-MONTESINOS, YE (2002), ‘Parameters afecting the conversion of alginic acid to sodium alginate’, Ciencias Marinas , vol. 28, no. 1, pp 27–36.

AYAL, HA and MATSUHIRO, B (1987), ‘Polysaccharides from nuclear phases of Iridaea ciliata and I. membranacea’, Hidrobiologia, 151/152, pp. 531–534.

BELLION, C, BRIGAND, G, PROME JC, WELTI, D and BOCIEK, S (1983), ‘Identifi cation et car-act é risation des pr é curseurs biologiques des carragh é nanes par spectroscopie de RMN 13C’, Carbohydrate Research , vol. 119, pp. 31–48.

BIXLER, H (1996), ‘Recent developments in manufacturing and marketing carrageenan’, Hydrobiologia vol. 326, no. 32, pp. 735–37.

BIXLER, HJ and PORSE, H (2011), ‘A decade of change in the seaweed hydrocolloids industry’, Journal of Applied Phycology , vol. 23, pp. 321–335.

CALUMPONG, HP, MAYPA, AP and MAGBANUA, M (1999), ‘Population and alginate yield and quality assessment of four Sargassum species in Negros Island, central Philippines’, Hydrobiologia , vol. 398, no. 399, pp. 211–215.

CHANG, PR, YU, J, MA, X and ANDERSON, DP (2011), ‘Polysaccharides as stabilizers for the synthesis of magnetic nanoparticles’, Carbohydrate Polymers , vol. 83, pp. 640–644.

CHOPIN, T, BUSCHMANN, AH, HALLIN, C, TROELL, M, KAUTSKY, N, NEORI, A, KRAEMER, GP, ZERTUCHE-GONZALEZ, JA and NEEFUS, C (2001), ‘Integrating seaweeds into marine aquaculture systems: a key toward sustainability’, Journal of Applied Phycology , vol. 37, pp. 975–986.

COPPI, G, IANNUCCELLI, V, LEO, E, BERNABEI, MT and CAMERONI, R (2001), ‘Chitosan-Alginate microparticles as a protein carrier’, Drug Development and Industrial Pharmacy , vol. 27, no. 5, pp. 393–400.

CRAIGIE, J (1990), ‘Cell wall’, In: KM Cole and RG Sheath (eds), Biology of the Red Algae , Cambridge, Cambridge University Press.

DAVIS, TA, RAMIREZ, M, MUCCI, A and LARSEN, B (2004), ‘Extraction, isolation and cad-mium binding of alginate from Sargassum spp’, Journal of Applied Phycology, vol. 16, no. 4, pp. 275–284.

DAWES, CJ, STANLEY, NF and STANCIOFF, DJ (1977), ‘Seasonal and reproductive aspects of plant chemistry and ι -carrageenan from Floridean Eucheuma (Rhodophyta, Gigartinales)’, Botanica Marina , vol. 20, pp. 137–147.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 37: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 511

© Woodhead Publishing Limited, 2013

DE STEFANO, C, GIANGUZZA, A, PIAZZESE, D and SAMMARTANO, S (2005), ‘Modelling of proton and metal exchange in the alginate biopolymer’, Analytical and Bioanalytical Chemistry , vol. 383, no. 4, pp. 587–596.

DESLANDES, E, FLOC ́ CH JY, BODEAU-BELLION, C, BRAULT, D and BRAUD, JP (1985), ‘Evidence for ι -carrageenans in Solieria chordialis (Solieriaceae) and Calliblepharis jubata , Calliblepharis ciliata , Cystoclonium purpureum (Rhodophyllidaceae)’, Botanica Marina , vol. 28, pp. 317–18.

DRAGET, KI, SMIDSROD, O, and SKJAK-BRAEK, G (2005), ‘Alginates from algae’, In: A Steinb ü chel and SK Rhee (eds), Polysaccharides and Polyamides in the Food Industry: Properties, Production and Patents I . Wiley-VCH, Weinheim.

FENORADOSOA, TA, ALI, G, DELATTRE, C, LAROCHE, C, PETIT, E, WADOUACHI, A and

MICHAUD, P (2010), ‘Extraction and characterization of an alginate from the brown seaweed Sargassum turbinarioides Grunow’, Journal of Applied Phycology , vol. 22, pp. 131–137.

Food Chemicals Codex (1981), Third Edition, Washington, DC, National Academy Press.

FREILE-PELEGRIN, Y, and MURANO, E (2005), ‘Agars from three species of Gracilaria (Rhodophyta) from Yucat á n Peninsula’, Bioresource Technology , vol. 96, pp. 295–302.

FREILE-PELEGRIN, Y, and ROBLEDO, D (1997), ‘Infl uence of alkali treatment on agar from Gracilaria cornea from Yucat á n, Mexico’, Journal of Applied Phycology , vol. 9, pp. 533–539.

FREILE-PELEGRIN, Y, ROBLEDO, D, PEDERS É N, M, BRUNO, E and R Ö NNQVIST, J (2002),‘Effect of dark and salinity treatment in the yield and quality of agar from Gracilaria cor-nea (Rhodophyceae)’, Ciencias Marinas , vol. 28, no 3, pp. 289–296.

FROMHOLT, LP (1998), ‘Carrageenan-containing product and a method of producing same’. US Patent No. 5,777,102.

GAO, HZ and ZEPP, RG (1998), ‘Factors infl uencing photoreactions of dissolved organic matter in coastal river of the southern United States’, Environmental Science Technology , vol. 32, pp. 2940–2946.

GOREN Š EK, M and BUKO Š EK, V (2006), ‘Zinc and alginate for multipurpose textiles’, Acta Chimica Slovenica , vol. 53, no. 2, pp. 223–228.

GREER, CW and YAPHE, W (1984), ‘Characterization of hybrid (beta-kappa-gamma) car-rageenan from Eucheuma gelatinae J. Agardh (Rhodophyta, Solieriaceae) using car-rageenases, infrared and 13 C-nuclear magnetic resonance spectroscopy’, Botanica Marina , vol. 27, pp. 473–478.

GUISELEY, KB (1970), ‘The relationship between methoxyl content and gelling temper-ature of agarose’, Carbohydrate Research , vol. 13, pp. 247–256.

HANSEN, M (1987), E for additives. Thorson Publishing Group. Wellingborough. HAUG, A (1964). Composition and properties of alginates . Report 30. Norwegian

Institute Seaweed Research, Throndheim, Norway. HAUG, A, LARSEN, B and SMIDSROD, O (1966), ‘A study of the constitution of alginic acid

by partial acid hydrolysis’, Acta Chemica Scandinavica, vol. 20, pp. 183–190. HERN Á NDEZ-CARMONA, G and AGUIRRE-VILCHIS, M (1987), ‘Propiedades de intercambio

i ó nico de Macrocystis pyrifera durante la pre-extracci ó n á cida, para la extracci ó n de alginatos’, Investigaciones Marinas CICIMAR , vol. 3, no. 2, pp. 53–64.

HERN Á NDEZ-CARMONA, G and CASAS-VALDEZ, MM (1985), ‘Precipitaci ó n del á cido alg í nico y su conversi ó n a alginato de sodio en muestras de Macrocystis pyrifera ’, Investigaciones Marinas. CICIMAR, vol. 2, no. 1, pp. 18–28.

HERN Á NDEZ-CARMONA, G, MCHUGH, DJ, ARVIZU-HIGUERA, DL and RODR Í GUEZ-MONTESINOS, YE (1999a), ‘Pilot plant scale extraction of alginate from Macrocystis pyrifera . Part 1. The effect of pre-extraction treatments on the yield and quality of alginate’, Journal of Applied Phycology , vol. 10. no. 6, pp. 507–513.

HERN Á NDEZ-CARMONA, G, MCHUGH, DJ, ARVIZU-HIGUERA, DL and RODR Í GUEZ-MONTESINOS, YE (2002), ‘Pilot plant scale extraction of alginates from Macrocystis

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 38: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

512 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

pyrifera 4. Conversion of alginic acid to sodium alginate, drying and milling’, Journal of Applied Phycology , vol. 14, no. 6, pp. 445–451.

HERN Á NDEZ-CARMONA, G, MCHUGH, DJ and L Ó PEZ-GUTI É RREZ, F (1999b), ‘Pilot plant scale extraction of alginates from Macrocystis pyrifera . 2. Studies on extraction con-ditions and methods of separating the alkaline-insoluble residue’ Journal of Applied Phycology , vol. 11, no. 6, pp. 493–502.

HORN, SJ, AASEN, IM and Ø STGAARD, K (2000), ‘Ethanol production from seaweed extract’, Journal of Industrial Microbiology and Biotechnology , vol. 25, pp. 249–254.

HSIEH, S, HUANG, BY, HSIEH, SL, WU, CC, WU, CH, LIN, PY, HUANG, YS and CHANG, CW (2010), ‘Green fabrication of agar-conjugated Fe 3 O 4 magnetic nanoparticles’, Nanotechnology , vol. 21, 445601, Epub 2010 Oct 8.

IMESON, AP (2000), ‘Carrageenan’, In GO. Phillips and PA. Williams (eds.), Handbook of Hydrocolloids, Cambridge: Woodhead Publishing, pp. 87–102.

IMESON, AP, LEDWARD, DA and MITCHELL, JR (1977) ‘On the nature of the interaction between some anionic polysaccharides and proteins’, Journal of the Science of Food and Agriculture , vol. 28, pp. 661–667.

ISTINI, SO and KUSUNOSE, M (1994), ‘Methods of analysis of agar, carrageenan and alg-inates in seaweeds’, Bulletin of Marine Science and Fisheries. Kochi University , vol. 14, pp. 49–55.

IWASAKI, K and MATSUBARA, Y (2000), ‘Purifi cation of alginate oligosaccharides with root growth-promoting activity toward lettuce’, Bioscience Biotechnology & Biochemistry , vol. 64, pp. 1067–1070.

JIN, Y, LI, HY, ZHANG, W, CONG, XJ and LIU, YL (2006), ‘Development of an eco-friendly agar extraction technique from the red seaweed Gracilaria spp’, Chinese patent No. 200610047762.2.

KELCO (1996). ‘Alginate products for scientifi c water control’, USA pp 1–33. KLUCK, JH (1970), ‘ Microwave apparatus for rapid heating of fl uids’, US Patent N .

3535482. KNUTSEN, SH, MYSLABODSKI, DE, LARSEN, B and USOV, AI (1994), ‘A modifi ed system of

nomenclature for red algal galactans’, Botanica Marina , 37 , 163–169. KRONBERGA, M, KARKLINA, D, MURNIECE, I and KRUMA, Z (2011), ‘Changes of agar-agar

gel properties after replacing sucrose by inulin syrup’, in E Straumite (ed), Proceedings of 6th Baltic Conference on Food Science and Technology FOODBALT-2011, ‘Innovations for Food Science and Production’ , Latvia University of Agriculture, Jelgava, Latvia.

LAHAYE, M and ROCHAS, C (1991), ‘Chemical structure and physico-chemical properties of agar’, Hydrobiologia , vol. 221, pp. 137–148.

LI, HY, YU, XJ, JIN, Y, ZHANG, W and LIU, YL (2008), ‘Development of an eco-friendly agar extraction technique from the red seaweed Gracilaria lemaneiformis ’, Bioresource Technology , vol. 99, pp. 3301–3305.

LOBBAN, CS and PJ HARRISON (1994), Seaweed Ecology and Physiology, Cambridge: Cambridge University Press.

MADERA-SANTANA, TJ, MISRA, M, DRZAL, LT, ROBLEDO, D and FREILE-PELEGRIN, Y (2009), ‘Preparation and characterization of biodegradable agar/poly (butylene adi-paterco-terephatalate) composites’, Polymer Engineering and Science , vol. 49, no. 6, pp. 1117–1126.

MADERA-SANTANA, T, ROBLEDO, D, AZAMAR, JA, R Í OS-SOBERANIS, CR and FREILE-PELEGRIN, Y (2010), ‘Preparation and characterization of low density polyethylene agar bio-composites: torque-rheological, mechanical, thermal and morphological proper-ties’, Polymer Engineering and Science , vol. 50, pp. 585–591.

MADERA-SANTANA, T, ROBLEDO, D and FREILE-PELEGRIN, Y (2011), ‘Physicochemical properties of biodegradable polyvinyl alcohol–agar fi lms from the red algae Hydropuntia cornea ’, Marine Biotechnology , vol. 13, pp. 793–800.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 39: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 513

© Woodhead Publishing Limited, 2013

MAEDA, H, YAMAMOTO, R, HIRAO, K and TOCHIKUBO, O (2005), ‘Effects of agar (kanten) diet on obese patients with impaired glucose tolerance and type 2 diabetes’, Diabetes, Obesity and Metabolism , vol. 7, no. 1, pp. 40–46.

MANDAL, V, MOHAN, Y and HEMALATHA, S (2007), ‘Microwave assisted extraction: an inno-vative and promising extraction tool for medicinal plant research’, Pharmacognosy Reviews , vol. 1, no. 1, pp. 7–18.

MATSUHASHI, T (1990), ‘Agar’, In: P Harris (ed.), Food Gels , London, Elsevier Science Publishers Ltd.

MATULEWICZ, MC, CIANCIA, M, NOSEDA, MD and CEREZO, AS (1989), ‘The carrageenan systems from tetrasporic and cystocarpic stages of Gigartina skottsbergii’, Phytochem istry, vol. 28, no. 11, pp. 2937 2941.

MCCANDLESS, EL (1978), ‘The importance of cell wall constituents in algal taxonomy’, In: DEG Irvine and JH Price (eds), Modern Approaches to the Taxonomy of Red and Brown Algae , London Academic Press, pp. 63–85.

MCCANDLESS, EL, CRAIGIE, JS and WALTER, JE (1973), ‘Carrageenans in the gametophytic and sporophytic stages of Chondrus crispus’, Planta (Berl) 112: 201–212.

MCCANDLESS, EL, WEST, JA and GUIRY, MD (1983), ‘Carrageenan patterns in the Gigartinaceae’, Biochem System Ecol , vol. 11, pp. 175–182.

MCHUGH, DJ (1987), ‘Production and utilization of products from commercial sea-weeds’, FAO Fisheries Technical Paper 288. Roma.

MCHUGH, DJ (2003), ‘A guide to the seaweed industry’, FAO Fisheries Technical Paper, no. 441, Rome.

MCHUGH, DJ (2006), ‘The seaweed industry in the Pacifi c islands’, ACIAR Working Paper No. 61.

MCHUGH, DJ, HERN Á NDEZ-CARMONA, G, ARVIZU-HIGUERA, DL and RODR Í GUEZ

MONTESINOS, YE (2001), ‘Pilot plant scale extraction of alginates from Macrocystis pyrifera . 3. Precipitation, bleaching and conversion of calcium alginate to alginic acid’, Journal of Applied Phycology , vol. 13, no. 6, pp. 89–106.

MCPEAK, RH and GLANZ, D (1984), ‘Harvesting California’s kelp forest’, Oceanus , vol. 27, no. 1, pp. 19–26.

MITCHELL, ME and GUIRY, MD (1983), ‘Carrageen: a local habitation or a name?’, Journal of Ethnopharmacology , vol. 9, pp. 347–351.

MOEN, E, HORN, S and OSTGAARD, K (1997), ‘Alginate degradation during anaerobic digestion of Laminaria hyperborea stipes’, Journal of Applied Phycology , vol. 9, pp. 157–166.

MOIRANO, AL (1977), ‘Sulfated seaweed polysaccharides’, In: HD Graham (ed.), Food Colloids , Westport, CT, AVI Publishing Co., pp. 347–381.

M Ø RC, Ý A (2008), ‘ Novel Alginate Microcapsules for Cell Therapy’, Ph. D. Thesis, Norwegian University of Science and Technology.

MURANO, E (1995), ‘Chemical structure and quality of agars from Gracilaria ’, Journal of Applied Phycology , vol. 7, no. 3, pp. 245–254.

MURILLO- Á LVAREZ, JI and HERN Á NDEZ-CARMONA, G (2007), ‘Monomer composition and sequence of sodium alginate extracted at pilot plant scales from three commercially important seaweeds from M é xico’, Journal of Applied Phycology , vol. 19, no. 5, pp. 545–548.

MYKLESTAD, S (1968), ‘Ion-exchange of Brown algae. Determination of rate mecha-nism for calcium hydrogen ion exchange for particles from Laminaria hyperborea and Laminaria digitata ’, Journal of Applied Chemistry , vol. 18, pp. 30–36.

NAGAOKA, M, SHIBATA, H, KIMURA-TAKAGI, I and HASHIMOTO, S (2000), ‘Anti-ulcer effects and biological activities of polysaccharides from marine algae’, BioFactors , vol. 12, pp 267–274.

NEORI, A, SHPIGEL, M and BEN-EZRA, D (2000), ‘Sustainable integrated system for culture of fi sh, seaweed and abalone’, Aquaculture , vol. 186, pp. 279–291.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 40: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

514 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

NISHIGAW A, K (1985), ‘Extract method of alginic acid’, In: K Nishigawa and M Chthara (eds), Research Methods of Algae, pp. 624–626.

PAINTER, TJ (1983), ‘Algal polysaccharides’, In: GO Aspinall (ed.), The Polysaccharides , vol. 2, New York, Academic Press, pp. 195–285.

PAJIC-LIJAKOVIC, I, PLAVSIC, M, NEDOVIC, V and BUGARSKI, B (2007), ‘Investigation of Ca-alginate hydrogel rheological behavior in conjunction with immobilized yeast cell growth dynamics’ Journal of Microencapsulation , vol. 24, no. 5, pp. 420–429.

PENMAN, A and REES, DA (1973), ‘Carrageenans-Part IX: Methylation analysis of galactan sulphates from Furcellaria fastigiata, Gigartina canaliculata, Gigartina chamissoi, Gigartina atropurpurea, Ahnfeltia durvillaei, Gymnogongrus furcellatus, Eucheuma cottonii, Eucheuma spinosum, Eucheuma isiforme, Eucheuma uncinatum, Aghardiella tenera, Pachymenia hymantophora and Gloiopeltis cervicornis, Structure of ε -carrageenan’, Journal of Chemical Society , Perkin Trans 1, pp. 2182–2187.

PERNAS, AJ, SMIDSR Ø D, O, LARSEN, B and HAUG, A (1967), ‘Chemical heterogeneity of Carrageenans as shown by fractional precipitation with potassium chloride’, Acta Chemica Scandinavica , vol. 21, pp. 98–110.

REES, D (1969), ‘Structure, conformation, and mechanism in the formation of polysac-charide gels and networks’, Adv Carbohyd Chem Biochem , vol. 24, pp. 267–332

REYES-TISNADO, R, L Ó PEZ-GUTI É RREZ, F, HERN Á NDEZ-CARMONA, G, VERNON-CARTER, J

and CASTRO-MOROYOQUI, P (2004), ‘Sodium and potassium alginates extracted from Macrocystis pyrifera algae for use in dental impression materials’ Ciencias Marinas , vol. 30, no. 3, pp. 189–199.

RINCONES, RE, YU, S and PEDERS É N, M (1993), ‘Effect of dark treatment on the starch deg-radation and the agar quality of cultivated Gracilaria lemaneiformis (Rhodophyta, Gracilariales) from Venezuela’, Hydrobiologia , vol. 260, no. 261, pp. 633–640.

ROBLEDO, D and FREILE-PELEGRIN, Y (2011), ‘Managing the interactions between plants and animals in marine multi-trophic aquaculture: integrated shrimp and valuable low food chain organisms with seaweeds’, In: Z Dubinsky and J Seckbach (eds), All Flesh is Grass, Plant-Animal Interrelationships Series: Cellular Origin, Life in Extreme Habitats and Astrobiology , vol. 16, 1st edition, Springer.

RODR Í GUEZ-MONTESINOS, YE, ARVIZU-HIGUERA, DL and HERN Á NDEZ-CARMONA, G (2008), ‘Seasonal variation on size and chemical constituents of Sargassum sinicola Setchel et Gardner from Bah í a de La Paz, Baja California Sur, M é xico’, Phycological Research , vol. 56, no. 1, pp. 34–39.

RODR Í GUEZ-MONTESINOS, YE, HERN Á NDEZ-CARMONA, G and ARVIZU-HIGUERA, DL (2005), ‘Aprovechamiento de los l í quidos residuales en la etapa de conversi ó n de alginato de calcio en á cido alg í nico durante el proceso de producci ó n de alginatos’, Oce á nides , vol. 20, no. 1, pp. 1–7.

SCHULDT, U and HUNKELER, D (2007), ‘Alginate-cellulose sulphate-oligocation micro-capsules: Optimization of mass transport and mechanical properties’, Journal of Microencapsulation , vol. 24, no. 1, pp. 1–10.

SCHWEIGER, RJ, GUARDADO-PUENTES, J, HERNANDEZ-GARIBAY, E, CALOCA-QUI Ñ ONES, C

and BAUTISTA-ALCANTAR, J (1992), ‘Planta Piloto de Carragenanos’, Reporte interno. Centro Regional de Investigaci ó n Pesquera de Ensenada. INP.

SCOTT, GV (1984), ‘Increasing viscosity of carrageenan-containing composition with microwave radiation’, US Patent No. 4,478,818.

SMIDSROD, O and DRAGET, KI (1996), ‘Chemistry and physical properties of alginates’, Carbohydrates in Europe , vol. 14, pp. 6–13.

SMITH, DB AND COOK, WH (1953), ‘Fractionation of carrageenin’, Archives of Biochemistry and Biophysics , vol. 45, pp. 232–233.

SOUSA, AMM, ALVES, VD, MORAIS, S, DELERUE-MATOS, C and GON Ç ALVES, MP (2010). ‘Agar extraction from integrated multitrophic aquacultured Gracilaria vermiculophylla :

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 41: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

Technologies for the extraction of algal polysaccharides 515

© Woodhead Publishing Limited, 2013

evaluation of a microwave-assisted process using response surface methodology’, Bioresource Technology , vol. 101, pp. 3258–3267.

STANCIOFF, DJ (1965), ‘Selective extraction of hydrocolloid fractions from sea plants’, US Patent No. 3176003.

STANLEY, N (1987), ‘Production, properties and uses of carrageenan’, In: DJ McHugh (ed.), Production and Utilization of Products from Commercial Seaweeds , FAO Fisheries Technical Papers 288, Rome.FAO , pp. 116–146.

TANG, JC, TANIGUCHI, H, CHU, H, ZHOU, Q and NAGATA, S (2009), ‘Isolation and charac-terization of alginate degrading bacteria for disposal of seaweeds waste’, Letters in Applied Microbiology , vol. 48, pp. 38–43.

TAVARES-SALGADO, L, TOMAZETTO, R, PAES-CINELLI, L, FARINA, M and MENEZES-AMADO-FILHO, G (2007), ‘The infl uence of brown algae alginates on phenolic compounds capability of ultraviolet radiation absorption in vitro’, Brazilian Journal of Oceanography , vol. 55, no. 2, pp. 145–154.

TRUUS, K, VAHER, M and TAURE, I (2001), ‘Algal biomass from Fucus vesiculosus (Phaeophyta): investigation of the mineral and alginate components’, Proceedings of the Estonian Academy of Sciences , vol. 50, no. 2, pp. 95–103.

TSENG, CK (1946), ‘Phycocolloids: useful seaweed polysaccharides’, In: J Alexander (ed.) Colloid Chemistry: Theoretical and Applied , Vol. 6, New York, Reinhold, pp. 629–734.

UNDP/FAO (1990), ‘ Training manual on Gracilaria culture and seaweed processing in China’, Training Manual 6 . Regional sea- farming development and demonstration project (RAS/90/002)-UNDP/FAO, People’s Republic of China, China.

USOV, AI (1998), ‘Structural analysis of red seaweed galactans of agar and carrageenan groups’, Food Hydrocolloids , vol. 12, pp. 301–308.

USOV, AI and ARKHIPOVA, VS (1981), ‘Polysaccharides of algae. XXX. Methylation of κ -carrageenan type polysaccharides of the red seaweeds Tichocarpus crinitus (Gmel.) Rupr., Furcellaria fastigiata (Huds.) Lam. and Phyllophora nervosa (De Cand.) Grev’, – Bioorganicheskaya Khimiya , vol. 7 , pp. 385–390.

USOV, AI and SHASHKOV, AS (1985), ‘Polysaccharides of algae. XXXIV: Detection of iota-carrageenan in Phyllophora brodiaei (Turn.) J. Ag. (Rhodophyta) using 13 C-NMR spectroscopy’, Botanica Marina , vol. 28 , pp. 367–373.

USOV, AI, YAROTSKY, SV and SHASHKOV, A (1980), ‘13 C NMR spectroscopy of red algal galactans’, Biopolymers , vol. 19, pp. 977–990.

VAN DE VELDE, F (2008), ‘Structure and function of hybrid carrageenans’, Food Hydrocolloids , vol. 22, pp. 727–734.

VAN DE VELDE, F and DE RUITER, GA (2002), ‘Carrageenan’, In: EJ Vandamme, SD Baets, A Steinb è uchel (eds), Biopolymers V 6 Polysaccharides II. Polysaccharides from Eukaryotes . Wiley, Weinheim, pp. 245–274.

VAUCHEL, P, ARHALIASS, A, LEGRAND, J, KAAS, R and BARON, R (2008a), ‘Decrease in dynamic viscosity and average molecular weight of alginate from Laminaria digitata during alkaline extraction’, Journal of Phycology , vol. 44, no. 2, pp. 515–517.

VAUCHEL, P, KAAS, R, ARHALIASS, A, BARON, R and LEGRAND J (2008b) ‘A new process for extracting alginates from Laminaria digitata : Reactive extrusion’, Food and Bioprocess Technology vol. 1, no. 3, pp. 297–300.

VAUCHEL, P, LEROUX, K, KAAS, R, ARHALIASS, A, BARON, R AND LEGRAND, J (2009), ‘Kinetics modeling of alginate alkaline extraction from Laminaria digitata ’, Bioresource Technology , vol. 100, no. 3, pp. 1291–1296.

WARBURTON, RN (2005), ‘Patient safety-how much is enough?’, Health Policy , vol. 71, pp. 223–232.

WILLIAMS, PA (2009), ‘Molecular interactions of plant and algal polysaccharides’, Structural Chemistry , vol. 20, no. 2, pp. 299–30.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221

Page 42: Conventional and alternative technologies for the ... · Conventional and alternative technologies for the extraction of algal polysaccharides G. Hern á ndez-Carmona, Instituto Polit

516 Functional ingredients from algae for foods and nutraceuticals

© Woodhead Publishing Limited, 2013

YABUR, R, BASHAN, Y AND HERN Á NDEZ-CARMONA, G (2007), ‘Alginate from the macroal-gae Sargassum sinicola as a novel source for microbial immobilization material in wastewater treatment and plant growth promotion’, Journal of Applied Phycology , vol. 19, no. 1, pp. 43–53.

YOUNIS, YMH, TECLEAB, S, GHEZA, T and RAHAMA, IH (2000), ‘Determination of the bio-mass and phycocolloid contents of some marine algae from Eritrea’, Journal KAU: Marine Science , vol. 11, pp. 19–25.

YU, S and PEDERS É N, M (1990), ‘The effect of salinfi ty changes on the activity of α -galactosidase of the red algae Gracilaria tenuistipitata and G. sordida ’, Botanica Marina , vol. 33, pp. 385–391.

Cop

yrig

hted

Mat

eria

l dow

nloa

ded

from

Woo

dhea

d Pu

blis

hing

Onl

ine

D

eliv

ered

by

http

://w

ww

.woo

dhea

dpub

lishi

ngon

line.

com

G

usta

vo H

erná

ndez

-Car

mon

a (2

12-7

2-72

7)

Tue

sday

, Nov

embe

r 05

, 201

3 6:

52:0

8 PM

IP

Add

ress

: 148

.204

.122

.221