ピタヤ(ドラゴンフルーツ)果汁を用いた麦汁の加工および発泡酒の品質への影響

誌名誌名 日本食品保蔵科学会誌

ISSNISSN 13441213

著者著者

広瀬, 直人前田, 剛希照屋, 亮高橋, 誠和田, 浩二

巻/号巻/号 40巻4号

掲載ページ掲載ページ p. 177-184

発行年月発行年月 2014年7月

農林水産省 農林水産技術会議事務局筑波産学連携支援センターTsukuba Business-Academia Cooperation Support Center, Agriculture, Forestry and Fisheries Research CouncilSecretariat

( 19 ) Food Preservation Science VOL. 40 NO.4 2014 CArticleJ 177

Wort Processing Using Pitaya (dragon fruit) Juices and its Effects on the Quality of Low-malt Beer

HIROSE Naoto*¥ MAEDA Gouki*¥ TERUYA Ryo*¥

TAKAHASHI Makoto*2!i and WADA Koji*2

* 1 Regional Agricultural System Section， Okinawa Prefectural Agricultural Research Center， 820 Makabe， Itoman， Okinawa 901-0336

* 2 Faculηof Agriculture， Universiηザ theRyl向IUS，1 Senbaru， Nishihara， Okinawa 903-0213

In this work， we evaluated the use of di旺erentpitaya fruits in the preparation of malt wort used in

the subsequent production of low.malt beers with characteristic colours. Pitaya extracts and juices

W巴reobtained from the fruits of Hylocereus polyrhizus (red pitaya) and H. undatus (white pitaya).

Preparation procedures were modified to optimize the influence of natural light and temperature on

pitaya betacyanins during pitaya sterilization and storage. Our results showed that a sterilization

temperature of 70o

C， time of 30 min， and growth in the shade resulted in improved wort sterilization，

with the characteristic colour of pitaya juice. Under identical culture conditions， using the wort

containing sterilized whole and red flesh pitaya juice with an initial betacyanin concentration of 164

mg/ R， the ethanol concentration was greater than 5.9%， with betacyanin retention of over 50% at th巴end of maturation. Additionally， sensory evaluation of the obtained low-malt beers showed that the use

of juice from red flesh pitaya was preferred to that of whole red pitaya by most testers. This is the

first report describing the processing of low-malt beer using pitaya juice.

(Received Dec. 19， 2013 ; Accepted May 15， 2014)

Key words : pitaya， betacyanin， low-malt beer， sterilization condition， sensory evaluation

ピタヤ，ベタシアニン，発泡酒，滅菌条件，官能評価

Pitaya fruits (dragon fruits) are native to Mexico，

Central America， and South AmericalJ and have

been grown in many Asian countries， including

Vietnam， Taiwan， the Philippines， Malaysia， and

Japan2J • Pitaya flesh contains high concentrations of

sugars (0 Brix 12. 5 ~ 14.8)， acids， vitamins， and

carotenes3J • Glucose and fructose are the principal

sugars in pitaya flesh， with small amounts of

oligosaccharideslJ. Pitaya has a number of varieties，

and each can be distinguished based on peel colour

and / or flesh colour. In J apan， the widely grown

varieties of pitaya are Hylocereus polyrhizus ( red-

peeled pitaya with red flesh; red pitaya) and H.

undatus (red-peeled pitaya with white flesh; white

pitaya). These two species of pitaya have recently

attracted attention due to their economic value and

potential health benefits. Previous studies have

reported the red-purple pigment and betacyanin

content in the peel and / or the flesh5)，6). The

betacyanins present in pitaya are betanin， isobetanin，

phyllocactin， and hylocerenin. Recent studies have

S Corresponding author， E-mail: h1l9314@agr.u-ryukyu.ac.jp

focused on the antioxidant activities of these

compounds， suggesting that these pigments may

protect against certain oxidative stress-related

disorders6). In addition， due to their relative stability

in the pH range from 4 to 7， betacyanins have

great potential as natural colouring agents that can

be added to a variety of foods and beverages7).

Around the world， beer is the most widely

consumed alcoholic beverage and it continues to be

a popular drink8). Currently， a large variety of beers

is available for consumption. In Japan， low-malt beer

is one of the most common alcoholic beverages. In

low-malt beer， the wort content is less than two

thirds that of regular beer， and supplementation

with sugar syrup and / or other carbohydrate

materials， iιtomato juice， ginger extract， or orange

peeI9)， 10)， is used to account for the low wort content.

Therefor巴， the flavour， visual appearance， taste， and

food functionality of these beverages are expected

to be unique， creating a beer product that is

distinct from regular beer. The use of pitaya fruits

178 Food Preservation Science VOL. 40 NO.4 2014 ( 20 )

for low-malt beer fermentation also has several

advantages. including providing a good carbon

source and producing a visually unique beer due to

the pigments within pitaya fruits. However. there

have been no reports describing the processing of

low-malt beer using pitaya fruits. Such an analysis

is important because some of the pigments in pitaya

could be discoloured by the high temperatures and

natural light present throughout the processS). These

factors must be studied in greater detail. especially

with respect to their influence on pigment stability

and the quality of low-malt beer produced from

pitaya.

In this study. we prepared pitaya extracts and

juices from red and white pitaya fruits and

investigated the in丑uence of natural light and

temperature conditions during the preparation

process on the characteristics of pitaya pigment. We

then produced low-malt beer from the selected

pitaya juices by yeast fermentation and assessed

beer qualities by evaluating the smells and tastes of

the beer products. To our knowledge. this is the

first report describing the processing of low-malt

beer using pitaya juice.

Materials and Methods

1. Sample preparation

( 1 ) Pitaya extract Two species of pitaya fruit

(red pitaya and white pitaya) grown in Okinawa.

]apan. were obtained from a local market store. The

flesh was separated from the red peel. and the flesh

and peel were then homogenized separately with a

2 X volume of 80% (v /v) aqueous ethanol solution

in a blender at room temperature for 15 min. Each

homogenate was then centrifuged at 3 .000 rpm for

10 min. and the supernatant was filtered (5 a filter

paper. Advantec. Tokyo. ]apan). The五ltratewas

beer (Kirin. Tokyo. ]apan). and the final betacyanin

concentration was adjusted to 56.5 mg / R. The

mixture was added to colourless storage bottles and

stored in a room with natural light (non-shaded

conditions) or a darkroom (shaded conditions) at

250

C for 32 days. The colours of the bottled samples

were measured with a Chroma Meter (Minolta CR

200. Tokyo. ]apan) using an illuminant D65 and a

100

observer angle. Data were expressed as Lへaへand b*川 . Colour di妊erences(LlE*) were assessed by

applying the equation LlE*= [(LlL*)' + (Lla*)' +

(Llb*) ']山門

3. Total betacyanin content

The betacyanin content was assessed using the

procedure described by STINTZING et a1.13) with slight

modifications. Data were expressed as betanin

equivalents using the following formula:

Betacyanin concentration (mg/ R) = As叩 xDF x

MW x (1.000/ε XL)

where AS30 is the absorbance at 530 nm. DF is

the dilution factor. MW is the molecular weight of

betanin ( MW betanin : 550 g / R ) .εis the extinction

molar coefficient (εb自問:60.000 mol/ R • cm). and L is the cell path (1 cm) .

4. Sterilization conditions

]uices prepared from whole f ruits and flesh of

red pitaya were mixed with water to adjust the

final betacyanin concentration to 246.4mg/ R. ]uices

were then processed in an autoclave (MLS-2420;

Sanyo. Osaka. ]apan) under sterilization conditions

at several temperatures (70-1210

C) and for several

durations (5-30 min). To quantify the number of

aerobic heterotrophic bacteria (total viable bacteria

count [TVC]). the autoclaved juice was plated onto

plates containing YM medium (10g/ R glucose. 3g/

R yeast extract， 3g/ R malt extract. 5g/ R peptone

[ pH 6 J) and incubated at 360

C. Colonies were

dried under reduced pressure to yield the pitaya counted after 48 h. Plate counts of aerobic

extract， which was subsequently used in the beer

preparation process.

( 2) Pitaya juice For red pitaya. whole fruits

(flesh and peel) and flesh were homogenized in a

blender at room temperature for 15 min. Each

homogenate was centrifuged at 3.000 rpm for 10

min. and the supernatant was obtained. The

supernatant was used as the pitaya juice during the

study.

2. Influence of natural light on pitaya colour

quality

The pitaya extract was mixed with a commercial

heterotrophic bacteria were expressed as colony-

forming units per mR (CFU/mR).

5. Low-malt beer processing

The brewing process included several steps. i.e..

mashing. wort processing. fermentation. and

maturation (Fig. 1).

( 1 ) Mashing and wort processing Sixty-six

grams of spray-dried malt (Muntons Plc.. Suffolk.

UK) was dissolved in 800mR water together with

sufficient glucose to achieve 6.9% w/v glucose. and

the solution was boiled for 5 min. After boiling. 2 g

of dried hops was added. and the solution was

( 21 ) CArticle) Low-malt Be巴rUsing Pitaya Juices 179

|Fin凶hedlow-malt be叫

Wort processmg

Fermentation

Fig. 1 Schematic showing the process for preparing

bottled low-malt beer using the pitaya extract

content. were measured throughout the primary

fermentation and after the completion of maturation.

Brix was measured using a digital refractometer

(AT AGO， Tokyo， ]apan) and was expressed in Brix

units. The pH was measured using a pH meter (S

20; Mettler Toledo， Tokyo， ]apan). The betacyanin

retention (%) was calculated by comparing

betacyanin concentrations in final matured beer

samples to that prior to fermentation. The ethanol

content was determined by gas chromatography on

a polyethylene glycol 1，000 column (SUS 5 m X 3.0凹

i.d.; GL Science， Tokyo， ]apan) coupled with a

flame ionization detector14). All experiments were

carried out in triplicate， and all data were expressed

as means.

7. Sensory evaluation

The sensory profiles of low-malt beers prepared

using the whole pitaya or the pitaya flesh juices

from red pitaya were analysed using quantitative

descriptive analysis ( QDA ) 15) by a trained taste

panel (seven tasters). Sample temperature was

regulated to 8::t 2'C prior to service. and

approximately 50 me was poured into each glass. Tasters rated six attributes for flavour (hoppy and

boiled for another 15 min. The solution obtained off-flavour)， visual appearance (form stability)， taste

was filtered through both 500-pm and 75-pm stainless

steel meshes， and the filtrate was mixed with the

autoclaved pitaya juice to adjust the final

betacyanin concentration to 82， 104， or 164rng/ R，

These wort products were used as the base worts

in the following experiments.

( 2) Fermentation and maturation The dried

ale yeast Safale 04， Saccharomyces cerevisiae

(Fermentis， Marcqen Barouel， France)， was used in

this study. The dried yeast (0.5g) was added to 10

me of aqueous glucose solution (10% ) in 50 -me Erlenmeyer flasks and incubated at 25'C for 20 min.

The base wart solution (800me) was inoculated with

the rehydrated yeast solution and then cultivated

under light-shielded conditions at 20'C for 6 days

(primary fermentation). After fermentation， an

aliquot (320mR，) of the yeast culture supplemented

with 1.8g glucose was added to a 330-me coloured

pressure bottle. The bottle was capped， and the

mixture was further fermented at 20'C for 2 days

(secondary fermentation) before final maturation at

4 'c for 21 days. 6. Quality parameters

Quality parameters， namely the sugar content

( Brix) ， pH， betacyanin retention， and ethanol

(gustatory feel and tingling)， and overall perception，

scoring the intensity of each attribute on a scale of

0~5 (0 = no aroma or no taste or extremely bad;

5 = strong aroma or strong taste or excellent). The

colour (body colour and form colour) was also

judged on a scale of 0~5 (0 = no red colour; 5 =

extremely intense red colour). One beer was

duplicated in order to determine the consistency of

the scoring.

Results and Discussion

1. Influence of natural light on the colour quality

of pitaya extracts

First. we evaluated the stability of the betacyanin

pigment derived from pitaya extracts subjected to

natural light during storage. Two plant parts (the

flesh and peel) from two species (red pitaya and

white pitaya) were used in this study. Table 1

shows the betacyanin concentrations of the

individual pitaya fruits. In the case of red pitaya，

the betacyanin concentrations in both the flesh and

peel were 16.2 and 14.3mg/100g fresh weight (FW).

respectively. Conversely， white pitaya contained

betacyanin in only the peel， and this pigment was

not detected in the flesh. Thus. white pitaya flesh

( 22 )

Table 3 The influence of sterilization on total viable bacterial count and betacyanin concentration in red pltaya JUlce

2014 NO.4 VOL.40 Food Preservation Science

Table 1 The betacyanin concentration in the extracts prepared from the 2 varieties of pitaya

180

TVC Betacyanin Betacyanin Sterile (CFUhnA) (mgl A ) retention (%) conditions

Whole Flesh Whole Flesh Whole Flesh

Total betacyanin

(mg/100g FW) Parts Variety

91. 6

81. 0

72.4

67.8

55.8

6.9

93.9

83.4

73.6

68.9

62.4

8.8

225.7

199.7

178.3

167.1

137.5

16.9

231. 4

205.6

181. 4

169.8

153.7

21. 6

1411

ハU

ハU

ハUAU

5

7

n

U

ハununu

噌

E4

句

EA

70'C， 5min

70'C， 15min

70'C， 30min

80'C， 15min

100t，15min

121 'C，15min

16.2

14.3

Flesh

Peel Red pitaya

N.D.

10.3

Flesh

Peel White pitaya

100

lighe7). Therefore， pitaya extracts stored in

shade should provide the available pigment because

colour value di旺erencesof less than 1.5 cannot be

easily detected by human eyes'8). Additionally， the

red pitaya flesh and peel are likely to be the most

practical choice for low-malt beer processing

compared with white pitaya due to the total

betacyanin concentration.

2. Influence of thermal

quality in pitaya juices

The influence of temperature on colour quality in

pitaya is also an important factor when the pitaya

juice is sterilized， as the betacyanin content can

easily be decreased by heat treatment叫. To

evaluate the optimum conditions for aerobic

heterotrophic bacteria sterilization， with the lowest

possible pigment degradation， the juices from whole

fruits and the flesh of red pitaya were heated to

various temperatures for 5 -30 min and the TVC

and betacyanin concentrations were measured

(Table 3). As expected， in samples heated for 15

min， the betacyanin concentrations in juices

prepared from whole fruits and flesh decreased with

increasing temperatures， especially at temperatures

higher than 121 'c. Interestingly， heated whole pitaya juice had a slightly higher betacyanin concentration

compared to that in the pitaya juice prepared from

the heated flesh， indicating greater retention of

betacyanin pigments in the former. Wu et al.6)

reported that the concentration of phyllocactin， a

major component of betacyanins， in the red pitaya

peel was higher than that in the flesh. In addition，

after heat treatment. most of the red betanin was converted into a bright yellow betacyanin

degradation product. whereas red phyllocactin was

transformed into red betanin with a nearly identical

the

colour

100

on

246.4

processmg

246.4 >100 >100 Not heated

may not be considered a good source of betacyanins.

The e妊ectsof natural light on the colour quality of

the red pitaya flesh and peel extracts and the

white pitaya peel extract were then examined.

Initially， the extracts were mixed with a

commercially available beer for examination under

conditions that were as close as possible to those of

the finished product. Table 2 lists changes in the

colours of pitaya extracts after storage for 32 days

with or without exposure to natural light. When

exposed to natural light. the colour di任erenceswere

significantly more pronounced in extracts derived

from the red or white pitaya peels (2.21 and 2.94，

respectively)， as compared to that obtained from

the flesh of the red pitaya (1.18). In contrast. colour

differences of the extracts from red and white

pitaya peels decreased to 0.68 and 0.77， respectively，

when samples were stored in the shade.

Interestingly， there was little di妊erence in the

colour of the red pitaya flesh extract， regardless of

storage conditions. These data indicated that natural

light had a greater e妊ecton the pigments in red

and/or white pitaya peels than on that in red

pitaya flesh. Woo et al.16) reported that the colour

change in pitaya juice could likely be due to

changes in betacyanin structure. In addition， betanin

/ isobetanin and betanin / phyllocactin ratios have

been shown to change with light exposure，

indicating that alterations in pigment patterns may

be induced upon illumination， especially using UV

Table 2 Chromatic parameters of low -malt beer prepared using pitaya extract under non-shading or shading conditions

Colour difference (LlEつ

Shading

0.77

1.10

0.68

Non-shading

1.18

2.21

2.94

Fl巴sh

Peel

Parts

P巴elWhite pitaya

Red pitaya

Variety

colour19). Hence， the total retention of betacyanin

pigments and red compounds appears to be lower

in whole pitaya juice as compared to that in the

flesh， under the same temperatures. However， the

TVC values of juice prepared from whole fruits and

those of juice prepared from the flesh were under

the detection limit following heat treatment of the

juice at temperatures greater than 800

C for 15 min.

Interestingly， increasing the heating time at 700

C to

30 min was found to sterilize a巴robicheterotrophic

bacteria completely， with minimal betacyanin

degradation. Taken together， it was inferr巴d that

the optimum condition for r巴d pitaya juice

sterilization was heating the juice at 700

C for 30

min， and subsequent experiments were carried out

under these conditions

3. Quality characteristics of low-malt beer using

various pitaya juices

During fermentation and maturation， a number of

paramet巴rs CBrix， pH， betacyanin retention， and

ethanol content) were monitored. Fig. 2 shows the

OBrix， pH， and betacyanin retention profiles of wort

samples containing different concentrations of whole

and red flesh pitaya juices (final betacyanin

concentrations of 82， 104， and 164mg/ R) during the

6 -day f巴rmentationperiod (primary fermentation)

and at the end of maturation (after 29 days). Brix

values reflect the concentration of sugar (the major

component)， followed by the concentrations of other

soluble solid contents， which constitut巴 theminority.

The Brix values of each wort for which the red

pitaya juice was added before fermentation ranged

from 13.5 to 14.9， and the values were r巴duced

similarly from 6.7 to 7.5 (Fig. 2a). With a decrease

in Brix， ethanol was successfully produced，

regardless of whether whole fruit or red flesh

pitaya juices were used in the wort preparation

(Fig. 3). The low-malt beer obtained at the end of

maturation was characterized by an acceptable

ethanol content of approximately 6.4% (range， 5.9-

6.9%). However， the betacyanin retention decreased

with reduction in pH in all samples during primary

fermentation (Fig. 2 b and Fig. 2 c). In general.

betacyanins were stable in a pH range of 4 to 7')

The pH values of whole fruit and flesh samples

prepared with different concentrations of betacyanins

for the first 3 days of primary fermentation were

estimated to be approximately 3.9， 4.0， and 4.2 for

samples prepared with 82， 104， and 163 mg / R

betacyanins， respectively， which may explain the

CArticleJ

7

181

29

一←Whole(82mgl 1)→・Flesh(幻mg/l)4 ト Whole(104mgl 1) -(30・Flesh(l04 mgl e ) 『←Whole(l64mgl 1) -/r・FI凶h(l64mgl 1)

--Whole(82 mg/l)ー←Flesh(82 mg!l) ___ Whole(104 mg/l)ー 白Flesh(l似 mg/l)司-Whole(l64 mg/e)・e・Flesh(l64mg/l)

345 Time(Days)

6 2

Low-malt Beer Using Pitaya Juices

l 5 0

(b)

6

~ 11 凶

9

( 23 )

巳d

A

笠

間門同

29 6 345 Time(Days)

2 1 3 0

(c)

渓 l∞ロ。+-'

~ 75 +-'

182 Food Preservation Science VOL. 40 NO.4 2014 ( 24 )

attributable not only to pH but also to other

mechanisms. A more detailed comparison showed

that the betacyanin retention in beer samples

prepared with whole red pitaya juice was slightly

higher than that in samples prepared from pitaya

flesh and with the same concentration of

betacyanins. This observation may be attributable to

the same process of betacyanin decomposition

described in section 3.2. Among the worts tested.

only the worts for juices prepared from whole fruits

or flesh. with an initial betacyanin concentration of

164 mg / R. retained ov巴r 50% of the betacayanin

cont巴ntat the end of maturation. Whole and red

flesh pitaya jUICe samples with an initial betacyanin

concentration of 164mg/ R could thus be used to

produce low-malt beer having a good red colour.

and the beer produced from such extracts should

perform very well in the sensory evaluation.

4. Sensory evaluation

Two types of low-malt beers using red pitaya

juice prepared from whole fruits (BPW) and flesh

( BPF) were used in this study and were

considered top fermented ale beers with 5.9% and

6.5% ethanol and 92.5 and 87.6 mg / R betacyanin.

respectively. Tasters evaluated six attributes for the

flavour (hoppy and off-flavours). appearance (whole

colour. form colour. and form stability). taste

(mouth fe巴1and tingling). and overall perception.

Fig. 4 shows the preference scores from this

evaluation. In terms of flavour. the sensory scores

of both low-malt beers were similar with regard to

Overall rec巴ptlOnE

:' Hoppy' Flavour:"

Mouthfeel'. ". Taste

. Off-flavors Tingling

• • • • ・ Colour ..... (Foam)

ー-BPW

---BPF

Visual

Fig. 4 Qualitative descriptive analysis ( QDA) profiles

for sensory values of low-malt beer using red pitaya jUICe

BPW. low-malt beers using whole red pitaya juice; BPF. low malt beers using red pitaya f1esh juice.

hoppy and 0任flavours and the scores were

relatively low. indicating that the peel did not a旺ect

the hoppy aroma or 0妊-flavourof the beer during

fermentation and maturation as compared with the

effects of the flesh.

The wort containing red pitaya juice had a

strong red colour. which reflected the appropriate

colour attributes of BPW and BPF. The body

colours of both BPW and BPF were a strong red

and received the same score of 5.0 from the tasters.

Interestingly. BPF had a significantly stronger red

foam colour than BPW. BPF showed acceptable

foam stability (3.8). whereas the foam stability of

BPW was r巴lativelypoor (3.3). Isohumulone derived

from hops and malt proteins. contributes to the

stabilization of beer foam. and promotes foam cling201 •

Additionally. various polyphenols easily interact with

malt proteins and form precipitates. which lead to a

decrease in beer foam211 • Generally. the total

polyphenol content in red pitaya peel is higher than

that in the fleshG1 • and this may therefore explain

the poor foam stability of BPW compared to that of

BPF. Many physical and chemical properties of beer

such as form head and the carbon dioxide. protein.

and polyphenol content have been described in the

literature as contributors to mouth feel 221 Although

both BPW and BPF had acceptable tastes. BPF had

a slightly superior taste than BPW. which was

likely due to the higher foam stability of BPF. The

tingling sensation produced by b巴eris mainly due

to the beer alcohol concentration羽 1 The di妊erence

in the ethanol levels of BPW (5.9%) and BPF (6

5 %) was clearly perceived by testers. which was

reflected in a higher tingling score for BPF

compared with that of BPW. The overall perception

score of BPF (3.9) was also higher than that of

BPW (3.3). although the general impressions for

both BPW and BPF were similar with regard to

flavour. body colour. and mouth feel. Therefore. low-

malt beer prepared using red flesh pitaya juice was

preferred to that prepared using whole red pitaya

juice by most testers

Conclusions

In the present work. we evaluated the basic

colour qualities of pitaya fruits that were used to

modify the characteristics of malt wort. Our aim

was to apply the wort to the brewing and the

production of low-malt beer having characteristic

pitaya colour. In this study. we used two species of

( 25 ) CArticleJ Low-malt Beer Using Pitaya Juices 183

pitaya (red pitaya and white pitaya) and found that

betacyanin was present in most pitaya products.

with the concentration being the highest in red

pitaya flesh (16.2mg/100g). followed by red pitaya

peel and white pitaya peeL The exception was the

white pitaya flesh. which contained no detectable

betacyanin. Natural light had a greater influence on

both red and white pitaya peel extracts than on

red pitaya flesh. Therefore. we concluded that

protection from natural light was required to

prevent colour degradation of the pitaya juice

during brewing and storage. Whole fruit and red

flesh pitaya juices were completely sterilized with

minimal betacyanin degradation at 700

C for 30 min.

Under identical conditions using wort containing

sterilized juices prepared from whole fruit and red

flesh pitaya at an initial betacyanin concentration of

164 mg/ i. the concentration of ethanol reached over

5.9%. with a betacyanin retention of over 50% at

the end of maturation. Additionally. a sensory

evaluation of the resulting low-malt beer prepared

using whole fruit and red flesh pitaya juice was

used to test the beers: the tasters evaluated

flavour. visual appearance. taste. and ov巴rall

perception. Although the general impressions of

both low-malt beers were similar with regard to

flavour. body colour. and mouth feel. beer prepared

using the flesh juice-treated wort was preferred to

that prepared using the whole fruit juice-treated

wort by most testers. These results should provide

a basic guideline for the brewing of low-malt beers

using pitaya fruits and demonstrate a novel

application of pitaya fruits.

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ピタヤ(ドラゴンフルーツ)果汁を用いた

麦汁の加工および発泡酒の品質への影響

広瀬直人*1・前田剛希*1・照屋 亮*1

高橋誠"9・和田浩二叫

* 1 沖縄県農業研究センター(干901-0336 沖縄県糸満市真壁820番地)

* 2 琉球大学農学部(〒903-0213 沖縄県西原町千原 1)

本研究では，ピタヤ(ドラゴンフルーツ)の色特徴を

生かした発泡酒の醸造を目的として， 2種類のピタヤ

(レッドピタヤおよびホワイトピタヤ)を用いた麦汁の

評価を行った。ピタヤの殺菌および貯蔵条件の最適化の

ために，ピタヤの主色素ベタシアニンの自然光および温

度に対する影響を調べた。その結果，暗所下， 70o

C， 30

分の加熱処理によって最も色調が高い状態で滅菌され，

また本条件で、滅菌したレッドビタヤ果汁(全果および果

肉)を含む麦汁を用いてアルコール発酵を行ったとこ

ろ， 50%以上のベタシアニンを保持した状態で，アルコ

ール濃度は5.9%以上にまで達した。さらに官能検査で

は，全果果汁と比べて，果肉果汁を用いた発泡酒が特に

好まれる結果が得られた。

(平成25年12月19日受付，平成26年5月15日受理)