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Journal of Cereal Science 53 (2011) 25e30

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Journal of Cereal Science

journal homepage: www.elsevier .com/locate/ jcs

Effects of roasting on barley b-glucan, thermal, textural and pasting properties

Paras Sharma a, Hardeep Singh Gujral a,*, Cristina M. Rosell b

aDepartment of Food Science and Technology, Guru Nanak Dev University, Amritsar-143005, Indiab Food Science Department, Institute of Agrochemistry and Food Technology (IATA-CSIC), Valencia, Spain

a r t i c l e i n f o

Article history:Received 12 January 2010Received in revised form3 August 2010Accepted 17 August 2010

Keywords:BarleySoluble b-glucanCooked starchRoasting

* Corresponding author. Tel.: þ91 183 2258802x34E-mail address: hsgujral7@yahoo.co.in (H.S. Gujra

0733-5210/$ e see front matter � 2010 Elsevier Ltd.doi:10.1016/j.jcs.2010.08.005

a b s t r a c t

Different hulled barley cultivars were subjected to roasting in hot sand (280 �C) and the effects on b-glucanextractability, physico-chemical, thermal and pasting properties were studied. The grain puffed uponroastingandgrainhardness andcolourdifferenceDEwere significantly lowered. The roastedbarleyflourhadsignificantly higherwater absorption andwater solubility index. The cultivarsDWR-28, RD-2503 andPL-172had the highest total b-glucan content (up to 5.47%). Roasting brought about a decrease in the solubleb-glucan content in all the cultivars and this decrease ranged from 4.9 to 25.3%. The b-glucan extractabilitywas not affected by the roasting process but roasting lowered the ratio of soluble to insoluble b-glucancontent by 8.1e41.9%. Roasting significantly affected the pasting and thermal properties of the flours,together with an increase in the cooked starch content that ranged from 28.8 to 43.1%.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

Barley (Hordeum vulgare L.) is an ancient and important cerealgrain and occupies about 9.4% of the total area under cerealproduction (FAO, 2007). The predominant type of cultivated barleyis hulled, having a tough fibrous husk, which is used as a maltingand brewing grain. Worldwide, barley has been mainly used forfeed and alcohol production. However, its high content of dietaryfiber has motivated the interest in increasing the consumption ofbarley based foods. The use of barley as a human food should beencouraged because it has one of the highest levels (2e10%) ofb-glucan. The b-glucans behave as a peculiar fiber because they arepresent in both soluble and insoluble forms and around 54% of totalb-glucan is soluble in water and classified as soluble fiber (Anker-Nilssen et al., 2008). Also b-glucans have the health benefits asso-ciated with insoluble fiber’s ability to relieve constipation. Solubleb-glucans are recognized as healthy polymers due to their benefitsin cholesterol lowering and glycemic index reduction, effects thatare beneficial in the prevention and management of various dietrelated diseases, such as diabetes and cardiovascular disease(Jenkins et al., 2000).

A simple way of increasing the consumption of barley is byincluding barley in food products with attractive sensory charac-teristics. However, the physiological effect of food supplementedwith barley largely depends on the barley variety and the pro-cessing treatments applied to the grains (Izydorczyk et al., 2000).

29; fax: þ91 183 2258820.l).

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Roasting is a simple and convenient process that uses dry heat forshort periods of time for improving grain characteristics. Roastedgrains exhibit improved texture, enhanced crispiness and volumedue to puffing (Hoke et al., 2007). Roasting also improves colour,extends shelf life, enhances flavor and reduces the antinutrientfactors of cereals and legumes (Gahalawat and Sehagal, 1992).Moreover, roasting of grains leads to the gelatinization of starch anddenaturation of proteins, thus improving their digestibility. In Indiaroasted barley, commonly called Sattu has been consumed for agesand is considered a traditional health food. Barley after roasting isground into flour and is mixed in water along with sugar andconsumed as a refreshing drink. However, no information is avail-able about the effect of roasting on thermal, textural and pastingproperties of barley and its effect on the total, soluble and insolubleb-glucan content.

It is likely that thermal treatment of the barley grains modifiesthe characteristics of the starches and the content and properties ofthe b-glucans, which have great influence in determining theutilization of barley for food purposes. The objectives of the presentinvestigation were to empirically investigate the changes duringroasting of barley grains, regarding the changes in physico-chem-ical, textural, pasting and thermal properties of common hulledbarley cultivars with special attention to the variation in total,soluble and insoluble b-glucan content.

2. Raw materials and miscellaneous analytical material

Common hulled barley cultivars DWR-28 (two rowed) andPL-172, PL-426, RD-2503, RD-2508, RD-2035, RD-2052, RD-2552

P. Sharma et al. / Journal of Cereal Science 53 (2011) 25e3026

(six rowed) were procured from Central State Seed Farm, Sriganga-nagar, Rajasthan, India. b-glucan and starch damage assay kit wereprovided by Megazyme International, Ireland and Termamyl 120L(Thermostable a-amylase) was procured from Novozyme, Denmark.Each test was performed in triplicates on a dry weight basis. Allchemicals usedwere of analytical grade andMilli Qwater (Millipore,France) was used in all analytical tests.

2.1. Grain roasting

Hulled barley (400 g) conditioned to a moisture content of 10%so as to eliminate the effect of differences in moisture content onroasting behavior was roasted at 280� 5 �C for 20 s in a traditionalsand roaster. The roaster consisted of an iron pan having a diameterof 915 mm and depth of 610 mm and contained 2 kg of sand. Theroaster was fired with a diesel burner. The grain was vigorouslystirredwith the sand to ensure uniform heating. It was immediatelyremoved from the hot sand by sieving and spread on a marble slabfor cooling. Roasted barley after cooling was dehusked in a ricepolisher McGill Rice miller No. 2 (Rapsco Brookshire TX, USA) asdescribed by Sharma and Gujral (2010) and ground in the NewportSuper Mill (Newport, Australia) to pass through a 250 mm sieve toobtain roasted barley flour.

2.2. Grain physical characteristics

The bulk density was evaluated by measuring the weight ofa known volume of control and roasted barley sample. Thousandkernel weight was determined by weighing one thousand kernels.Puffing index¼bulk density of control/bulk density of roastedbarley. The hardness of the dehusked grain (control and roasted)was determined on a texture analyzer (Model TA-HDi StableMicrosystem, Surrey, U.K). The barley grains (control and roasted)were compressed by 1 mm using a probe (TA-11ss) havinga diameter of 25 mm. A 50 kg load cell was used and the test speedwas 1 mms�1.

2.3. Colour of flour

Colour measurement of flour was carried out using a HunterColorimeter fitted with an optical sensor (Hunter AssociatesLaboratory Inc. Restan VA., USA) on the basis of CIE L*, a*, b* coloursystem. The colour difference (DE) was calculated as:

DE ¼ ½ðDL*Þ þ ðDa*Þ þ ðDb*Þ�1=2

2.4. Water absorption capacity and water solubility index

Water absorption capacity of flour (control and roasted) wasmeasured by the centrifugation method of Anderson et al. (1969).Flour (3 g) was dispersed in 25 ml of distilled water taken in pre-weighed centrifuge tubes. The dispersion was stirred for 10 minfollowed by centrifugation for 25 min at 3000 g (REMI, C 24,Mumbai, India). The supernatant was collected by allowing thetube to stand inverted for 10 min. The supernatant obtained wasdried in a hot air oven for 24 h at 105 �C. The results were expressedas % water solubility index.

2.5. Quantification of total and soluble b-glucan

The total, insoluble and soluble b-glucan was quantifiedaccording to the method reported by McCleary and Glennie (1985)using a ‘b-glucan assay kit’ (Megazyme International Ireland Ltd.,

Wicklow, Ireland). For mixed linkage total b-glucan, flour (0.5 g ondry weight) was placed in polypropylene tubes and 1 ml of ethanol(50% v/v) was added followed by sodium phosphate buffer (5 ml,20 mM, pH 6.5) andmixed well with the help of a vortex mixer. Thetubes were incubated in a boiling water bath and cooled to 40 �C.The enzyme, lichenase (10U) was added, tubes were incubated for1 h at 40 �C with intermediate vortex mixing. The volume of eachtubewas adjusted to 30 ml with water, the content of the tubes wasmixed thoroughly, and centrifuged at 1000g for 10 min. An aliquot(0.1 ml) was transferred to three test tubes. Sodium acetate buffer(0.1 ml, 50 mM, pH 4.0) was added to one of these tubes (reactionblank) and, in the other two tubes 0.2U b-glucosidase was addedand incubated at 40 �C for 15 min. After incubation, 3.0 ml glucoseoxidase peroxidase determining reagent was added in all tubes andincubated at 40 �C for 20 min. The absorbance was noted at 510 nmwith a spectrophotometer (Shimadzu, UV-2450, Kyoto, Japan).Standard glucose solution was used as standard and calculationcarried out.

For determination of water soluble b-glucan, the flour wassuspended in 10 ml aqueous ethanol (80% v/v) and incubated ina steam water bath for 5 min to inactivate enzymes. After coolingthe tubes to room temperature, centrifugationwas done at 12,000gfor 10 min and ethanol drained off. The pellet was suspended in10 ml water and incubated at 65 �C for 30 min, followed bycentrifugation at 6000g for 10 min. The supernatant was recoveredand the pellet was further extracted with 10 ml and ultimately with5 ml water. The supernatants obtained in each step were pooledand estimated for soluble b-glucan as described by McCleary andGlennie (1985). The b-glucan in the residues was defined as insol-uble b-glucan.

2.6. b-Glucan extractability

Extraction of b-glucan was carried out as reported by Bhatty(1995), barley flour (10 g) was mixed with NaOH and extracted for1 h at room temperature and further centrifuged at 6000g (REMI, C24,Mumbai, India) for 15 min. The residuewas again extractedwithNaOH for 1 h and centrifuged at 6000g for 15 min. The supernatantswere pooled and pH adjusted to 6.5 with HCl. Calcium chloride(70 mg/100 ml) and Termamyl 120L (0.1 ml/100 ml) were added.The contents were incubated at 96 �C for 1 h with shaking and thesuspension was cooled to room temperature (25 �C) and the pHadjusted to 4.5 with HCl. The supernatant was again centrifuged at6000g for 15 min and thepellet discarded. Ethanolwas added to 50%final concentration and kept overnight at 4 �C, then centrifugedagain at 6000g for 15 min. The crude gumwas resuspended inwaterand washed with 50% ethanol twice, centrifuged again, the pelletwas homogenized in water and freeze dried (Heto, LL 3000,Denmark).

2.7. Pasting properties

Pasting properties of flours (control and roasted) were studiedusing a Rapid Visco Analyzer (Newport Scientific Pty Ltd., Australia)using the Standard profile 1. Flour (3 g on a 14%moisture basis) wasplaced in the canister and 25 ml water was added. The suspensionwas mixed thoroughly with a plastic paddle to prevent lumpformation before RVA analysis that involved a heating step of50e95 �C at 6 �C/min, a holding phase at 95 �C for 5 min, a coolingstep from95 �C to 50 �C at 6 �C/min and a holding phase at 50 �C for2 min. The peak, breakdown, final, setback viscosity, peak time andpasting temperature were reported.

Table 1Effects of roasting on physical properties and colour of flours from different barley cultivars.

Cultivars Puffing index Hardness roasted grain (N) DE Water absorption capacity (g/g) Water solubility index (%)

DWR-28 2.3d 49.8a 83.7a 4.4a 13.8e

RD-2503 2.1c 51.8a 86.5b 4.4a 12.6c

RD-2508 1.9a 31.3a 86.1b 4.6a 11.6a

RD-2035 2.3d 39.7a 85.8b 4.4a 13.8e

RD-2052 1.9a 28.0a 85.2b 3.9a 12.5c

RD-2552 2.4e 43.8a 87.4c 4.5a 11.5a

PL-172 2.4e 44.5a 85.7b 4.4a 12.0b

PL-426 2.0b 48.1a 86.5b 4.1a 13.1d

a, b, c, d and e superscripts are significantly (p< 0.05) different row wise in different cultivars.

P. Sharma et al. / Journal of Cereal Science 53 (2011) 25e30 27

2.8. Thermal properties

The thermal characteristics of barley flours (control and roasted)were analyzed using a Differential Scanning Calorimeter (DSC-821e,

Degree of gelatinizationð%Þ ¼h1�

�DHgelof roasted sample=DHgelof control sample

�i� 100

Mettler Toledo, Switzerland) equipped with a thermal analysis datastation and robotic device to handle the aluminum pan. The sample(5 mg, dry weight basis) was loaded into a 40 ml aluminum pan anddistilled water was added (flour to distilled water ratio was 1:2.3).The sample was hermetically sealed and allowed to stand for 1 h atroom temperature before heating in a DSC. The DSC analyzer wascalibrated using indium and an empty aluminum pan was used asreference. The sample was heated at a rate of 10 �C/min from 30 to100 �C, onset temperatures (T0), peak temperature (Tp), endsettemperature (Tc) and enthalpy of gelatinization (DHgel) werecalculated automatically. The gelatinization range (R) was (TCeT0),

ppp

p

pp

p

pp

pp

p

p

p

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0.0

1.0

2.0

3.0

4.0

5.0

6.0a

b

DWR-28 RD-2503 RD-2508 RD-2035 RD-2052 RD-2552 PL-172 PL-426

)%

(n

ac

ul

ga

te

bl

at

oT

Control Roasted

qqqq

q

q

q

qppppp

p

p

p

0.00

1.00

2.00

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5.00

6.00

DWR-28 RD-2503 RD-2508 RD-2035 RD-2052 RD-2552 PL-172 PL-426

)%

(n

ac

ul

ga

te

be

lb

ul

oS

Control Roasted

Fig. 1. Effect of roasting on total and soluble b-glucan in different barley cultivars,mixed linkage total b-glucan (a) and soluble b-glucan (b). Superscripts p and q showsignificant difference (p< 0.05) of roasting within a cultivar.

the peak height index (PHI) was calculated by the ratio DHgel/(TPeT0). The degree of gelatinization (DG) was calculated asreported by Holm et al. (1988) and results were reported in percentdegree of gelatinization.

2.9. Cooked starch content

The term cooked starch has been used for the starch granulesthat have been damaged as a result of bursting/gelatinisation uponroasting. The cooked starch is thus susceptible to enzymaticbreakdown and has been measured enzymatically using the ‘StarchDamage Assay Kit’ (Megazyme International Ireland Ltd., Wicklow,Ireland). The results were reported as % cooked starch.

2.10. Statistical analysis

Analysis of variance (ANOVA) was carried out and Fishers leastsignificant difference (LSD) test was used to describe means with95% confidence. The Pearson correlation coefficients were calcu-lated by SPSS statistical software (SPSS Inc., Chicago, Illinois, USA) ata probability level of p< 0.05.

3. Result and discussion

3.1. Physical properties of barley

Roasting lowered the thousand kernel weight of the barley by2.1e13.7% and bulk density by 47.8e59.1%. The roasting of barley

p

p

p

p

p

pp

p

p

p

p

p

p

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p

84.00

86.00

88.00

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94.00

96.00

98.00

DWR-28 RD-2503 RD-2508 RD-2035 RD-2052 RD-2552 PL-172 PL-426

Beta g

lu

can

extractab

ility (%

)

Control Roasted

Fig. 2. Effect of roasting on extractability of b-glucan in different barley cultivars,superscripts having similar letter (p) show insignificant difference of roasting withincultivars.

P. Sharma et al. / Journal of Cereal Science 53 (2011) 25e3028

grain also significantly decreased the length/breadth ratio andincreased the geometric mean diameter (data not reported). Thepuffing index, indicator of volume of puffed grain (Hoke et al.,2007), significantly varied among cultivars and ranged from 1.9 to2.4. Roasting leads to expansion of grain derived from the disor-ganization of starchy endosperm and expansion of cavities presentin endosperm (Mariotti et al., 2006). A negative correlation(R¼�0.78) existed between the puffing index and bulk density ofroasted barley.

3.2. Grain hardness

Grain hardness is important because it affects energy require-ments during milling (Moss et al., 1980). The hardness of thedehusked roasted grain significantly varied among the cultivars(Table 1), and it decreased significantly (p< 0.05) as a consequenceof the roasting. Decrease in hardness upon roasting was alsoreported by Murthy et al. (2008) for wheat. This effect could beattributed to the fact that the grain expands, gelatinization of starchtakes place and fissures develop, resulting in the reduced hardness(Mridula et al., 2008).

3.3. Colour characteristics of flour

Roasting lowered the L* value (lightness) of the barley flours by2.7e7.0% (data not reported). The a* value (redness) of the flourswas increased by 102e255% and the b* value (yellowness) wasincreased by 12.0e44.8% upon roasting. The total colour difference(DE) of flour significantly (p< 0.05) varied among cultivars andranged from 83.7 to 87.4 (Table 1). The roasting of barley signifi-cantly decreased the DE for all the cultivars by 3.0e6.5%. Changes inthe colour parameters (L*, a* and b*) are attributed to Maillard(Rufian-Henares et al., 2009) and browning reactions that producebrown pigments with low and high molecular weight in theadvanced stage of the browning reaction (Hofmann, 1998).

3.4. Water absorption capacity and water solubility index

Roasting increased the water absorption capacity of the flours by171e216% and the water solubility index by 17.4e33.3% (Table 1).Griffith et al. (1998) reported an increase in the WAC and WSI indifferent cereals and legumes after roasting. The formation of capil-laries and a porous structure in the endosperm and also the presenceof higher levels of damaged starch have been suggested as a possiblereason (Mariotti et al., 2006) for increase in water absorptioncapacity in puffed barley. Starch has the tendency to become solubleafter different cooking treatment (Jones et al., 2000).

3.5. Total, insoluble and soluble b-glucan

The highest total b-glucan was observed for DWR-28 (5.47%)and lowest total b-glucan was observed for RD-2508 cultivar.

Table 2Pasting properties of roasted barley flours from different cultivars.

Cultivars Peak viscosity (cP) Breakdown viscosity (cP) Final viscosity (c

DWR-28 523b 66a 1064d

RD-2503 478a 72a 957b

RD-2508 473a 60a 910a

RD-2035 685c 116d 1072d

RD-2052 709d 84b 1346e

RD-2552 726d 101c 1406f

PL-172 869e 131e 1613g

PL-426 459a 70a 988e

a, b, c, d, e, f and g superscripts are significantly (p< 0.05) different column wise in diffe

Roasting did not have any significant effect on the total b-glucancontent (Fig. 1a). The soluble b-glucan ranged from 1.95 to 3.07% incontrol barley and it was significantly lowered after roasting(Fig. 1b). Izydorczyk et al. (2000) reported that hydrothermaltreatments (steaming and autoclaving using temperatures up to121 �C) did not increase the amount of soluble b-glucan in differentbarley cultivars. Since we have used a higher temperature (280 �C)for a short time the different effects on soluble b-glucan could beattributed to the differences in the thermal treatments. The highestand the lowest decrease in soluble b-glucan were observed for RD-2035 (25.3%) and RD-2552 (4.9%) cultivars, respectively. Theinsoluble b-glucan ranged from 2.0 to 3.0% in control barley flourand roasting significantly increased the insoluble b-glucan in all thebarley cultivars. The soluble to insoluble b-glucan ratio forthe control barley ranged from 0.73 to 1.51 whereas, after roasting,the ratio was lowered in all the cultivars and ranged from 0.52 to1.04. The highest decrease in the soluble to insoluble b-glucan ratiowas observed in RD-2035 (41.9%) and lowest in RD-2052 (8.1%).

3.6. b-Glucan extractability

The b-glucan extractability significantly varied among thecultivars (Fig. 2). The highest and the lowest b-glucan extractabilitywere observed for PL-172 and PL-426, respectively in control androasted barley. After roasting, b-glucan extractability showed someincrease; however it was insignificant. Bhatty (1995) reportedsimilar values for b-glucan extractability in barley and oat bran. b-glucan extractability (control barley) was positively correlated withwater absorption capacity (R¼0.70, p< 0.05).

3.7. Pasting properties of flour

Since roasted barley flour is reconstituted in water beforeconsumption, the pasting properties have been reported (Table 2).Roasting leads to a significant decrease in the peak (53e78%), final(15e57%), breakdown (64e92%) and setback (18e47%) viscositiesof the barley flour slurry whereas an increase was observed in thetime to peak (1e14%) and pasting temperature (5e16%). Similarresults were also reported for pasting properties in roasted oat(Cenkowski et al., 2006). After roasting, the loosely packed starchgranules that are partially gelatinized and damaged, easily hydrateand swell rapidly in the presence of heat and consequently produceless peak viscosity (Mariotti et al., 2006).

The pasting properties of barley flour obtained after roastingsignificantly varied among cultivars (Table 2). PL-172 showedhighest final viscosity and also had high b-glucan content. Peak andfinal viscosity showed a positive correlation (R¼0.74 and 0.67) withtotal b-glucan. Zhang et al. (1998) reported that the non-starchypolysaccharides such as b-glucan affected the pasting properties ofbarley flour.

P) Setback viscosity (cP) Peak time (min) Pasting temperature (�C)

644d 6.9a 94.0a

552b 7.0a 91.8a

496a 7.0a 88.8a

501a 7.0a 93.3a

724e 7.0a 87.9a

785f 7.0a 89.3a

876g 7.0a 86.2a

599c 7.0a 93.7a 0

rent cultivars.

Table 3Thermal properties of roasted barley flours from different cultivars.

Cultivars DH(J/g)

OnsetTo (�C)

PeakTp (�C)

EndsetTc (�C)

Degree ofgelatinization (%)

PHI

DWR-28 0.77h 52.1a 66.2d 78.7a 86.2a 0.05a

RD-2503 0.69f 51.9a 66.3d 80.9a 87.8b 0.05a

RD-2508 0.60e 54.2c 65.2b 75.9a 86.5a 0.06a

RD-2035 0.22b 56.5d 65.9c 71.3a 96.0f 0.02a

RD-2052 0.16a 56.8d 65.9c 70.7a 97.6g 0.02a

RD-2552 0.74g 57.8e 64.2a 70.6a 88.5c 0.12b

PL-172 0.42d 52.7b 64.3a 72.5a 94.0d 0.04a

PL-426 0.34c 52.6b 65.1b 72.3a 94.6e 0.03a

a, b, c, d, e, f, g and h superscripts are significantly (p< 0.05) different columnwise indifferent cultivars.

P. Sharma et al. / Journal of Cereal Science 53 (2011) 25e30 29

3.8. Thermal properties

Significant differences were observed in the thermal propertiesof the control and roasted barleyflour. The enthalpyof gelatinization(DHgel) for the roasted flour ranged from 0.16 to 0.74 J/g (Table 3)with the highest being for DWR-28 and the lowest being forRD-2052. Roasting lead to a significant decrease inDHgel that rangedfrom 86 to 98% as compared to control flour. This indicated that themajority of the starch was gelatinized during the roasting processand this was confirmed by the high degree of gelatinization thatranged from 86.2 to 97.6% (Table 3) in the roasted barley. The onsettemperature Towas loweredby4.5e14.0% after roastingwhereas theendset temperature Tc was increased by 0.2e15.3%. Upon roasting,significant increase (38e194%) was observed in the gelatinizationrange. The peakheight index (PHI) significantly decreased (93e99%)in all the cultivar after roasting.

Roasting leads to gelatinization of the starch, which agrees withthe observed decrease in DHgel. Holm et al. (1988) reported that thedegree of gelatinization (DG) ranged from 22 to 65% for rolledcereals, lower values than the ones obtained in the present study,attributed to difference in thermal treatment applied to grain.Granfeldt et al. (2000) reported a decrease in To and DHgel forroasted oat and steamed barley flakes.

3.9. Cooked starch

During the milling of grain some starch granules get mechan-ically damaged and the level of damaged starch depends upon thetexture of grain, type of seed, and force applied during milling(Hoseney, 1994). The level of damaged starch affects the flour char-acteristics like water absorption capacity. During the roastingprocess, the grain puffs and expands due to bursting of starchgranules in the endosperm. The damage caused to the starch gran-ules as a result of roasting has been termed cooked starch in thisstudy. The measure of the cooked starch content is an index of the

pppppppp

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q

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50.0

DWR-28 RD-2503 RD-2508 RD-2035 RD-2052 RD-2552 PL-172 PL-426

)%

(h

cr

at

sd

ek

oo

C

Control Roasted

Fig. 3. Effect of roasting on cooked starch in different barley cultivars, superscripts pand q show significant difference (p< 0.05) of roasting within a cultivar.

extent of modification of the structure of the native starch granulesby the roasting process. In the control samples the level of damagedstarch ranged from 2.1 to 3.1% (Fig. 3). This is the starch that gotdamaged during the milling of the control barley grain into flour.However the starch that became susceptible to enzymatic break-down after the roasting process has been termed cooked starch andit ranged from 28.8 to 43.1%. This substantial increase in the level ofcooked starch is attributed to the gelatinization and bursting ofstarch granules due to high roasting temperature. Mariotti et al.(2006) reported similar results for control and roasted barley.

4. Conclusions

The study revealed that large variations were found in thephysical characteristics, thermal and pasting properties of a range ofbarley cultivars. Roasting of barley significantly puffed the grain andchanged its colour. The thermal treatment induced starch gelatini-zation, lowered the peak and final viscosity and provoked a signifi-cant increase in the cooked starch. b-glucan extractability remainedunaffected after roasting, however the solubleb-glucanwas loweredwhich affected the ratio of soluble to insoluble b-glucan.

Acknowledgement

We sincerely thank Megazyme International Ireland Ltd., forproviding the b-glucan and starch damage assay kit.

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