Nutritional Composition of a Semi-Fermented Fish Product

J. Home Econ. Jpn. Vol. 50 No. 7 703•`712 (1999)

Nutritional Composition of a Semi-Fermented Fish Product

(Chapa Shutki) in Bangladesh

Mosammat Nazmanara KHANUM, Hitoshi TAKAMURA* and Teruyoshi MATOBA

Graduate School of Human Culture, Nara Women's University, Nara 630-8506, Japan * Faculty of Human Life and Environment , Nara Women's University, Nara 630-8506, Japan

The nutritional characteristics of a semi-fermented fish product, commonly known as chapa shutki in Bangladesh, were studied. Its crude protein, crude fat, and crude ash contents were 33.2, 17.0 and 12.2 %, respectively. The calcium, phosphorus, magnesium and iron contents of chapa shutki were higher than those of similar kinds of Japanese processed fish. The amino acid score of the protein was found to be 100, based on the provisional amino acid scoring pattern (FAO/WHO 1990). The percentage of available lysine was 97.6. Chemical changes in the amino acid residues scarcely occurred during

processing. Palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids were the major fatty acids of chapa shutki. Highly unsaturated fatty acids with 20 or more carbons were relatively low. No significant losses of unsaturated fatty acids were observed during the semi-fermentation process. An investigation of the extent of lipid oxidation showed that the carbonyl value and thiobarbituric acid-reactive substances value were 27 meq/kg of oil and 38 mg/kg of oil, respectively. The level of peroxidation was the very minimum. These feature indicite that chapa shutki can be considered a high-quality protein food.

(Received August 27, 1998; Accepted in revised form March 25, 1999)

Keywords: chapa shutki, fish, marine processed food, semi-fermented fish, fermentation, food

constituents.

INTRODUCTION

Indigenous fermented foods are native to a country

or culture. They are important for a number of reasons: a) these foods and food processes have survived and persisted over the centuries in the

developing countries, b) they are important for the nutrition of the poor people, and c) they generally involve low-cost methods for processing. For these

reasons, fermented foods are very important for a developing country like Bangladesh, where a large number of people suffer from various types of chronic

malnutrition, and where most babies are born underweight, since their mothers are chronically

malnourished (Islam 1998). Protein malnutrition is one of the most serious problems in Bangladesh. At

present, 59% of the households suffer from protein deficiency and millions of people consume a deplor-ably low amount of protein in their diets (Hossain 1991). The content of animal protein in the Bang-ladeshi diet is particularly low.

According to a report of the Bangladesh Bureau of

Statistics (1997), the average intake of animal protein is only 4.5 g per head per day, and about 80 % of this intake comes from fish. Although fish is abundant in

Bangladesh, the supply of fresh fish is not uniform throughout the country due to the lack of suitable transportation. Moreover, fisheries are highly season-

al due to climatic conditions. The total catch of fish in Bangladesh is very high during the rainy season. At that time, the fishermen whose principal means of

livelihood is the sale of fish cannot sell all of their catch, so a sizable quantity is wasted due to the lack

of preservation and distribution facilities. Thus, the total production of fish is not sufficient to meet the total national demand.

Under such circumstances, it is obviously neces-sary to look at processed fish foods to meet this demand. Processed foods, especially protein-rich

processed foods, are very rare in the Bangladeshi diet. At present, only a few home-processed fish are eaten as processed protein foods. Among them, chapa shutki is the most common and popular fish food

prepared by the natural fermentation of the small fish,* *To whom all correspondence should be addressed .

( 703 ) 39

J. Home Econ. Jpn, Vol. 50 No. 7 (1999)

A

B

Indian minor carp (Fig. 1). It is basically prepared by following a similar procedure to that employed for the

preparation of fish paste and sauce in other Southeast Asian countries (Ahmed 1979; Mansur et al. 1989); for example, "Bagoong" in Philippines, "Prahose" in

Cambodia, and "Pla-ra," "Pla-som," "Som-fuq," etc., in Thailand. These products are prepared under anaerobic conditions by traditional fermentation methods. Although there are differences in the detail

of preparation, the underlying principle is the same everywhere (Ahmed 1979; Mansur et al. 1989). Ex-

perimental results have indicated fish visceral en-zymes to be mainly responsible for the fermentation of these products (Uyenco and Lawas 1952; Vanveen 1965). In a few cases, however, the involvement of

bacterial activity has also been reported (Amano 1962). Although an enzymatic or bacteriological study

on the fermentation process for chapa shutki has

yet to be reported, it is assumed that both fish muscle

enzymes and bacterial enzymes are involved in the fermentation process. Traditional methods for produ-

cing fish paste and sauce involve 6-12 months of fermentation (Shimoda et al. 1996); however, in case

of chapa shutki, the fish are allowed to ferment for only 3-4 months. As a result, the final product is obtained as semi-solid in appearance and is therefore

termed a semi-fermented product (Mansur et al. 1989). Bhuiyan et al. (1989) have reported a new

semi-fermented powdered product from underutilized marine fish, and Mansur et al. (1989) described another type of ready-to-use powdered chapa shutki

from Puntius sp. Both products were prepared in the laboratory by using almost the same method as that

for chapa shutki involving an oven-drying process to make the powder. These products were found to be rich in protein and to have good acceptability by a

consumer test panel. However, such powdered

products are not commercially available. At present, people consume whole chapa shutki that is locally prepared from Indian minor carp by the fishermen. Chapa shutki forms an important part of the diet of many people in Bangladesh. This product is very

popular among Bangladeshis, because of its charac-teristic taste and flavor. However, information about

its nutritional and other health benefits is scant, except for a report by Ahmed (1979). Chapa shutki is

prepared by the traditional method of fermentation and it does not cost much nor require any technical knowledge. This product serves as a cheap source of

protein in Bangladesh. Scientific information regard-ing its nutritional value and protein quality is

necessary to make this food more popular among the

people, so that it can contribute much in improving the protein deficiency of the country.

This investigation has, therefore, been undertaken

primarily to clarify the nutritional quality and the acceptability of chapa shutki. We determined the

proximate composition, mineral content, amino acid and fatty acid spectra, and oil quality of commercially available chapa shutki. The commercial product was

prepared by a 90-day fermentation. A comparative investigation was also done in this study with samples fermented for 15, 30 and 60 days to observe the

biochemical changes occurring during the prepara-tion.

MATERIALS AND METHODS

Raw fish

Raw Indian minor carp (Burbus puntio) were

purchased fresh from a local market in Bangladesh

Fig. 1. Photographs of raw Indian minor carp (A) and chapa shutki (B)

40 ( 704 )

Nutritional Composition of a Semi-Fermented Fish Product (Chapa Shutki) in Bangladesh

and brought to Japan by air transport under properly

iced conditions. The specimens were stored at-30•Ž

until the investigation started, the time between the

purchase and-30•Ž storage being approximately 3

days.

Chapa shutki

Chapa shutki was prepared from raw fish by

following a traditional semi-fermentation method

commonly used in Bangladesh. Figure 2 shows a flow

chart for the preparation of chapa shutki. Raw fish was

purchased from a local market and gutted as quickly

as possible without any pre-washing. Fish oil was

separated from sunlight for 7 days. Meanwhile, four

sets of clay vats were soaked with previously collected

fish oil in such a way that no absorption of oil from

the fish body would occur during subsequent

ripening. After drying, the fish were sprayed with a

small amount of water and kept overnight. The

following day, they were divided into four batches and

poured into the vats ready for fermentation. The

mouth of each vat was then covered with a banana

leaf and plastered by a heavy layer of clay in order to

create anaerobic conditions inside the vat. The sealed

vats were then placed underground for periods of 15,

30, 60, and 90 days for fermentation. The product

prepared by 90-day fermentation is known as chapa

shutki. The fermented products were prepared in

Bangladesh and brought to Japan by air transport for

the investigation.

Sample preparation

Raw fish were gutted and scaled before the sample

was prepared for analysis. The semi-fermented fish

were scaled and cleaned properly. Then, both were

separately minced and finely homogenized with a

mortar and pestle. The resulting fish flesh was used

as samples for the subsequent analyses.

Proximate composition

The moisture, crude fat and ash contents of the raw

and semi-fermented fish samples were determined

according to the standard method of the Association

of Official Analytical Chemists (1970). The nitrogen

content was estimated by the micro-Kjeldhal method,

and the percentage of crude protein was calculated

by multiplying total nitrogen by a factor of 625.

Mineral content

To determine the mineral content, accurately

weighed samples (5 g) were taken in a porcelain

crucible, and ashed by heating with a gas burner and

then re-ashed in a muffle furnace for 16 h at 550•Ž.

The resulting ash was dissolved in 10 ml of 30%

HNO3 and diluted 200-fold with ultra-pure water. The

solution was then subjected to an ICP analysis with an

ICP-575 II instrument (Nippon Jarrell-Ash) according

to the method of Haraguchi et al. (1988).

Amino acid analysis

The fats were extracted from the sample by using a

chloroform/methanol mixture (2 : 1, v/v). The resul-

ting de-fatted sample was ground with a mortar and

pestle in the presence of acetone, and this de-fatted

fish powder was used as a sample for the amino acid

analysis. The sample was hydrolyzed with re-distilled 6

N HCl at 110•Ž for 24 h in an evacuated Pyrex tube. y -

Amino butyric acid was used as the internal standard.

To determine the sulfur amino acids, performic acid

oxidation and subsequent acid hydrolysis was carried

out according to Moore (1963). Alkaline hydrolysis

with 3.75 N NaOH for 16 h at 110•Ž was followed by an

amino acid analysis to determine tryptophan and

methionine sulfoxide according to the method of

Neumann (1967). Available lysine was determined

according to the procedure of Matoba et al. (1984),

which is a modification of the method Roach et al.

(1967). The quantitative amino acid determination

was carried out with an amino acid analyzer (Hitachi

L-8500), the contents of the different amino acids

recovered being expressed as g per 100 g of protein

Collection of fish

Gutting the fish and separating the oil from the gut

Drying the fish for at least 7 days

Sprinkling water on the dry fish and keeping overnight

Soaking clay vats with fish oil up to full saturation

Placing dry fish in the oil-soaked vats

Sealing the vats with banana leaves and a heavy layer of clay

Placing the vats underground for a period of 3 months for

fermentation

Fig. 2. Flow chart for the preparation of chapa shutki

( 705 ) 41

J. Home Econ. Jpn. Vol. 50 No. 7 (1999)

and compared with the FAO/WHO (1990) reference

pattern.

Fatty acid composition

Total lipids were extracted from the fish flesh by

following the method of Folch et al. (1966), using a

chloroform/methanol mixture (2:1, v/v). The extra-

cted lipids were subjected to methylation according to

the method of Christie (1973), and the converted

sample was analyzed with a Shimadzu GC-14 gas

chromatograph, using a flame ionization detector and

an HR-SS-10 capillary column (0.25 mm •~25 m). The

column temperature gradient was 3•Ž /min from 150-

220t. Peaks were identified by comparing with

authentic standards, and quantitative fatty acid data

were calculated directly as the percentage area.

Oil quality

Peroxide value (POV), carbonyl value (COV) and

thiobarbituric acid reactive substances (TBARS) were

determined as indices of the oil quality. POV was

determined iodometrically according to the standard

method of the Japan Oil Chemists' Society (1986)

(2.4.12-86) and spectrophotometrically by the method

of Asakawa and Matsushita (1980). COV was de-

termined according to the standard method of the

Japan Oil Chemists' Society (1986) (2.4.22-73), the

value being expressed as meq/kg of oil. TBARS was

determined according to the method of Ito et al.

(1988). Two milliliters of TBA reagent and 0.1 ml of

SDS (5 mg/ml in H2O) were added to 0.1-0.3 g of fish

oil and mixed well, an ethanol solution (0.1 ml) of

BHT (0.22 %) being added to the mixture to prevent

oxidation during the TBA reaction. The mixture was

then heated in boiling water for 15 min. After cooling,

acetic acid (1 ml) and chloroform (2 ml) were added

and the mixture shaken thoroughly. The absorbance

of the upper layer was recorded at 535 nm after

centrifugation. TBARS is expressed as mg of ma-

londialdehyde per kg of oil.

RESULTS AND DISCUSSION

The raw fish used in this experiment were Indian minor carp, commonly called puti in Bangladesh (Fig.

1-A). There are various types of minor carp of different sizes (2-10 cm), the smaller fish (2-6 cm) usually being used to prepare chapa shutki (Fig. 1-B). This fish is somewhat similar in appearance to the

Japanese freshwater fish, Crucian carp (funa). We, therefore, compared our results for raw fish with the

published values in the Standard Table of Food Composition in Japan (Resource Council of Science and Technology Agency 1982, 1989, 1991) for raw

Crucian carp (the edible part), and three other commonly consumed Japanese raw fish, horse mackerel (aji, the edible part), Japanese pilchard

(maiwashi, the edible part), and pond smelt (wakasagi, the whole fish). The results for commercially available chapa shutki were compared with those of the

published values for two semi-dried Japanese prod-ucts, mildly salted, semi-dried whole Japanese pil-chard (iwashi no nama boshi) and salted, semi-dried

split horse mackerel (aji no hiraki boshi). Proximate composition

To evaluate the nutritional quality of chapa shutki,

the proximate compositions of the raw fish and of the semi-fermented fish were determined. Table 1 shows the proximate composition of raw Indian minor carp

and its commercially available semi-fermented prod-uct, chapa shutki. Compared with Japanese fish

(Standard Table of Food Composition in Japan), the protein content of raw Indian minor carp (18.3 g) was almost the same as that of both horse mackerel (18.7

g) and Crucian carp (18.2 g), slightly lower than that of Japanese pilchard (19.2 g), and slightly higher than that of pond smelt (17.1 g) on a wet-weight basis. Its crude fat content was 1.4 and 1.2 times higher than

that of Crucian carp and pond smelt, respectively, but was 1.9 and 3.8 times lower than that of horse

Table 1. Proximate composition of raw Indian minor

carp and chapa shutki

Data are expressed as means + SD (n=3). Values in

parentheses are percentages to dry weight.

42 ( 706 )


mackerel and Japanese pilchard, respectively. The ash content of raw Indian minor carp was almost the same

as that of pond smelt and approximately twice that of the three other Japanese fishes. Compared with mildly salted, semi-dried Japanese pilchard and with salted,

semi-dried split horse mackerel, chapa shutki contained 1.5 and 1.6 times more protein, respectively,

per 100 g of the edible part. The fat and ash contents (17.0 and 12.2 g, respectively) were also higher in chapa shutki than the amounts in salted, semi-dried horse mackerel (6.8 g) and mildly salted, semi-dried

Japanese pilchard (15.6 g) per 100 g of the edible

portion. Compared to the Japanese raw fishes, Indian minor carp contained a comparable amount of

protein, a higher amount of ash, and a lower amount of fat. Chapa shutki prepared from raw Indian minor

carp also showed comparatively higher amounts of

protein, fat, and ash on a wet-weight basis than those of the Japanese raw and processed products. Mineral composition

Table 2 shows the mineral contents of raw Indian minor carp and of commercially available chapa shutki. Sodium, potassium, calcium, phosphorus and magne-

sium were the predominant mineral elements in both these samples. The mineral composition of raw Indian

minor carp was then compared with that of horse mackerel, Japanese pilchard and Crucian carp

(Standard Table of Food Composition in Japan). The calcium content of raw Indian minor carp (302 mg) was considerably higher than that of horse mackerel

(65 mg), Japanese pilchard (70 mg) and Crucian carp (100 mg), but was less than that of pond smelt (750 mg). The phosphorus content (130 mg) was much lower than that of pond smelt (680 mg) and slightly

lower than that of the other three Japanese fishes

(160-190 mg). Raw Indian minor carp contained 8.8 and 21 times less sodium and 3.9 and 4.4 times less

potassium than those of horse mackerel and Japanese

pilchard, respectively. The iron content of minor carp was comparable with that of Japanese pilchard and Crucian carp, but the amount was about 30 % of that

of pond smelt (5.0 mg). The other minerals were either comparable or higher in content than those of

the Japanese fishes. As shown in Table 2, chapa shutki contained

approximately 2.0 and 3.4 times more calcium and

phosphorus, respectively, than those in the raw fish. The sodium, potassium, magnesium and iron contents

of chapa shutki were also considerably higher those in the raw fish. Chapa shutki was found to contain larger amounts of zinc and copper than those in raw fish.

In comparison with mildly salted, semi-dried Japa-

nese pilchard, and salted, semi-dried split horse

mackerel, chapa shutki showed higher values for all the minerals determined, except for sodium and potas-sium. Although chapa shutki contained a higher

amount of sodium than the two freshwater raw fishes

(Indian minor carp, 17 mg; Crucian carp, 30 mg), the amount was 1.5 times less than that in raw Japanese

pilchard, a salt-water fish (360 mg). In addition, the sodium content of chapa shutki (247 mg) was far below that of mildly salted, semi-dried Japanese pilchard

(750 mg) and salted, semi-dried split horse mackerel (1,200 mg) per 100 g of fish. Among the other minerals, the greatest variation appeared in the

amount of calcium, which was 7.8 times higher in chapa shutki than in Japanese processed fishes. The

potassium content of chapa shutki was about half that in these two semi-dried Japanese products. Protein quality 1. Amino acid composition

The results of the amino acid analysis of raw Indian minor carp and its semi-fermented products at various stages are shown in Table 3. Raw minor carp

contained higher levels of aspartic acid, threonine, serine, glutamic acid, glycine, alanine, valine, and leucine per 100 g of crude protein than horse

mackerel, Japanese pilchard, Crucian carp, and pond smelt. In addition, cysteine and methionine in raw minor carp were comparable with those in the four

Japanese raw fishes. The results in Table 3 indicate that the amino acid

contents of raw puti fish and chapa shutki were not

significantly different and that there was hardly any change in the amino acid composition before and after fermentation. The results also suggest that any

Table 2. Mineral content of raw Indian

minor carp and chapa shutki

Data are expressed as means +SD (n=3).

( 707 ) 43


chemical changes in the amino acid residues were very rare during processing. Decreases in the availability of lysine and sulfur-containing amino acids

during processing have been reported (Miller et al. 1965; Matoba et al. 1984). The amount of lysine and

its availability are meaningful criteria for evaluating the protein nutritional quality of a food, because its availability is lost with the modification of the E-amino

group of the lysine residue. Available lysine in the proteins of raw minor carp and chapa shutki was 98.9 and 97.6%, respectively. Particular attention has also

been paid to the sulfur amino acids, because their levels in fish protein are not particularly high (Miller 1956; Chalupa and Fisher 1963). The result of the

present investigation reveals that available lysine in the protein of chapa shutki was comparable with that in the raw fish. Damage to the sulfur-containing amino

acids also insignificant, because a very low amount of methionine sulfoxide was found in the fermented and

non-fermented samples (Table 3). 2. Amino acid score

The essential amino acid composition of the

proteins in raw Indian minor carp and in commercial-ly available chapa shutki are presented in Table 3,

together with the FAO/WHO (1990) recommended

pattern. Of the 10 essential amino acids, the contents of 6 (threonine, methionine, valine, leucine, isoleucine

and phenylalanine) were relatively higher in minor carp and chapa shutki than in the Japanese fishes. The amounts of all the essential amino acids in the raw

fish and chapa shutki were also higher than the recommended pattern. Proteins in both the raw fish and commercial chapa shutki have amino acid scores

of 100, are Crucian carp, and are comparable with egg, meat and milk in protein nutritional quality. Oil quality

1. Fatty acid composition Table 4 shows the fatty acid compositions of the

Table 3. Amino acid composition of raw Indian minor carp, semi-processed fish,

and chapa shutki

Data are expressed as means •}SD (n=3). * FAO/WHO reference pattern 1990.

* * Methionine sulfoxide.

44 ( 708 )


raw and semi-fermented products at various stages.

The relative percentages of eighteen fatty acids were identified in the total fatty acids, and traces of some unidentified fatty acids were also found. In raw minor

carp, the major fatty acids were palmitic (16 : 0),

palmitoleic (16: 1), stearic (18 : 0), oleic (18: 1), linoleic (18 : 2), and linolenic (18 : 3) acids. Compared

to those in Japanese fishes, the percentages of both the 18 : 2 and 18 : 3 fatty acids in minor carp were 13.4

times higher than those in horse mackerel and 6.7 and 4.7 times higher than those in .Japanese pilchard respectively (Standard Table of Food Composition in Japan). The percentage of icosapentaenoic acid (20 :

5) in Indian minor carp (0.6%) was much lower than that in horse mackerel (7.9%), Japanese pilchard

(13.0%), Crucian carp (6.5%) and pond smelt (11.3%).

The percentage of docosahexaenoic acid (22 : 6) was also lower in the raw fish (0.7%), in contrast with

horse mackerel (14.5%), Japanese pilchard (10.7%), Crucian carp (7.2%), and pond smelt (21.0%). As

shown in Table 4, the major fatty acids 16 : 0, 16 : 1, 18 : 0, 18 : 1, 18 : 2 and 18 : 3 in raw minor carp were also commonly found in commercial chapa shutki and in the semi-fermented product at different stages.

Each sample contained higher levels of 16 : 0 and 18 : 1 fatty acids. Highly unsaturated fatty acids with more than 20 carbons were considerably lower in both the

fermented and non-fermented samples. The fatty acid composition reveals that raw Indian

minor carp and its semi-fermented product of

different stages, including commercial chapa shutki, almost resembled each other. Although the raw fish

Table 4. Fatty acid composition, COV, and TBARS of raw Indian minor carp,

semi-processed fish, and chapa shutki

Data are expressed as means •}SD (n=3). * ND, not determined, **MDA, malondialdehyde.

( 709 ) 45


and chapa shutki showed characteristic features of

freshwater fish in their fatty acid composition (Table 4), the pattern was somewhat different from that of

the Japanese freshwater fishes. Compared to the Japanese freshwater fishes, the percentages of total unsaturated fatty acids in the total fatty acids were

relatively lower in both the raw minor carp and its semi-fermented products. Moreover, Indian minor

carp and its semi-fermented product both showed higher levels of 18 : 2 and 18 : 3 fatty acids and lower levels of 20 : 5 and 22 : 6 fatty acids than those in

Japanese freshwater fishes. These results might indicate an environmental variation in their habitats,

because the fatty acid composition of fish lipids is influenced by the geographical location, season of catch, temperature, maturity, and diet, etc. (Toyomizu

et al. 1975). Little loss of unsaturated fatty acid in the semi-fermented products was apparent, which sug-

gests a lower level of oxidation in the fermented products. 2. POV, COV and TBARS

The peroxide values (POV) of the oils of the raw

fish and chapa shutki were found to be 0 by both iodometric and spectrophotometric methods. COV and TBARS values for the raw fish and commercial

chapa shutki are presented in Table 4. In the present study, we were unable to successful-

ly determine POV, which may have been due to an

insufficient amount of oil being used for the determination. Furthermore, the presence of phos-

pholipids in the oil sample, which formed an emulsion when shaken, also hindered end point observation

(Lezerovich 1985). We were also unsuccessful in determining POV by the spectrophotometric method. The presence of phospholipids in the sample gave erroneous results in peroxide value when determined

by the highly sensitive spectrophotometric method

(Asakawa 1998, personal communication). However, the COV and TBARS values for raw Indian minor carp

and chapa shutki were not high enough to show any extensive oxidation of the semi-fermented products.

In general, hydroperoxides formed by lipid oxida-tion react with amino acid residues to reduce their

nutritional availability (Gardner 1979; Matoba et al. 1982). Damage to methionine occurs most extensive- ly, followed by tryptophan, histidine and lysine

(Motaba et al. 1984). In particular, methionine is oxidized mainly to methionine sulfoxide (Tannen-baum et al. 1969; Matoba et al. 1984). Cuq et al.

(1973) have reported that the formation of methionine sulfoxide in an intact protein leads directly to the

loss of methionine availability. However, in the

present study, no significant increase in methionine sulfoxide was apparent in the semi-fermented prod-

ucts during processing (Table 3). This suggests that the level of oxidation during fermentation was not

extensive. It should be noted that raw fish collected by fishermen in Bangladesh are usually left without

preservation. The time that elapsed between collect-ing the raw fish and preparing the semi-fermented

product is considered to be the reason for the slightly higher oxidative damage in the semi-fermented

products since the raw fish had already been oxidized

(Table 4). From the preceding discussion, it appears that raw

Indian minor carp and its commercial semi-fermented

product, chapa shutki are both rich in protein and ash content. The mineral composition reveals them to be

good sources of calcium, phosphorus and most of the trace minerals. There was no significant loss of chemical constituents resulting from fermentation. Both the raw fish and semi-fermented chapa shutki were found to contain sufficient amounts of essential

amino acids and in proper balance to serve as a high-quality food. Moreover, the fatty acid profile,

COV and TBARS values reveal the products to be acceptable in quality in terms of their low degree of lipid peroxidation. Therefore, chapa shutki can be

considered a high-quality protein source to improve the nutritional value of the cereal-based Bangladeshi diet.

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バングラデシュの半発酵魚製品(チャパ・シュトキ)の栄養成分組成

モサマットナズマナラカノム,高村仁知*,的場輝佳

(奈良女子大学大学院人間文化研究科,*奈良女子大学生活環境学部)

原稿受付平成10年8月27日;原稿受理平成11年3月25日

バングラデシュの半発酵魚製品チャパ・シュトキの栄養特性について研究を行った.粗タン

パク質,粗脂肪,および粗灰分含量はそれぞれ33.2,17.0,12.2%であった.カルシウム,

リン,マグネシウム,および鉄含量は相当する日本の魚加工品よりも高かった.暫定アミノ酸

スコアパターン(FAO/WHO1990)に基づくアミノ酸スコアは100であった.また,有効性

リジンは97.6%であった.加工中のアミノ酸残基の化学変化はほとんど起こらなかった.パ

ルミチン酸,パルミトレイン酸,ステアリン酸,オレイン酸,リノール酸,およびリノレン酸

が主要脂肪酸であった.炭素数20以上の高度不飽和脂肪酸は比較的少なかった.半発酵中の

不飽和脂肪酸の有意な減少は見られなかった.脂質酸化について調べたところ,カルボニル価

とチオバルビツール酸反応性物質値は27meq/kg油脂および38mg/kg油脂と低かった.この

ように,脂質酸化のおそれは少なく,チャパ・シュトキは良質なタンパク性食品と考えられる.

キーワード:チャパ・シュトキ,魚介,水産加工品,半発酵魚,発酵,食品成分.

48 ( 712 )

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