Biochemical profile of oyster Crassostrea madrasensis and its nutritional attributes

Abstract

Oysters are highly esteemed sea food and considered a delicacy throughout the world. Yet this resource is not optimally utilised in several parts of the world. The aim of this study is to highlight its nutritional importance. Biochemical composition and nutritional attributes of oyster meat are discussed. Proximate composition, fatty acid and amino acid profiles and mineral content were determined in oysters (Crassostrea madrasensis). Moisture, protein, fat, carbohydrate and ash contents in the oyster were 82.64%, 9.41%, 3.25% 3.2% and 1.01%, respectively and it was rich in macro-minerals and trace elements especially selenium. Polyunsaturated fatty acids (PUFA) were highest of the total lipids among which eicosapentaenoic acid, docosahexaenoic acid and linoleic acid were the prominent fatty acids. The n-3/n-6 index was high indicating a predominance of n-3 fatty acids in the species. Total amino acid content was 99.33 g/100 g crude protein, of which, essential amino acid lysine was the most abundant. Valine had the lowest essential amino acid score (EAAS) (0.17) while threonine had the highest EAAS of 3.62. Chemical score was 17% and the lowest limiting amino acid was valine. Protein efficiency ratio, essential amino acid index and biological value of oyster were 3.92, 120.2 and 174.0, respectively which indicates that the protein is of superior quality. Data on biochemical composition, nutritional attributes and quality indices of C. madrasensis protein may prove important for future policies regarding exploitation of this species and for inducing favourable changes in consumer preferences.

Full text

FULL LENGTH ARTICLE
Biochemical profile of oyster Crassostrea madrasensis
and its nutritional attributes
K.K. Asha *, R. Anandan, Suseela Mathew, P.T. Lakshmanan
Biochemistry and Nutrition Division, Central Institute of Fisheries Technology, Cochin 682029, India
Received 24 June 2013; revised 16 January 2014; accepted 14 February 2014
KEYWORDS
Fatty acid;
Amino acid;
n3/n6 Index;
Essential amino acid score;
Crassostrea madrasensis;
Nutritional profiling
Abstract Oysters are highly esteemed sea food and considered a delicacy throughout the world.
Yet this resource is not optimally utilised in several parts of the world. The aim of this study is
to highlight its nutritional importance. Biochemical composition and nutritional attributes of oyster
meat are discussed. Proximate composition, fatty acid and amino acid profiles and mineral content
were determined in oysters (Crassostrea madrasensis). Moisture, protein, fat, carbohydrate and ash
contents in the oyster were 82.64%, 9.41%, 3.25% 3.2% and 1.01%, respectively and it was rich in
macro-minerals and trace elements especially selenium. Polyunsaturated fatty acids (PUFA) were
highest of the total lipids among which eicosapentaenoic acid, docosahexaenoic acid and linoleic
acid were the prominent fatty acids. The n-3/n-6 index was high indicating a predominance of
n-3 fatty acids in the species. Total amino acid content was 99.33 g/100 g crude protein, of which,
essential amino acid lysine was the most abundant. Valine had the lowest essential amino acid score
(EAAS) (0.17) while threonine had the highest EAAS of 3.62. Chemical score was 17% and the
lowest limiting amino acid was valine. Protein efficiency ratio, essential amino acid index and bio-
logical value of oyster were 3.92, 120.2 and 174.0, respectively which indicates that the protein is of
superior quality. Data on biochemical composition, nutritional attributes and quality indices of C.
madrasensis protein may prove important for future policies regarding exploitation of this species
and for inducing favourable changes in consumer preferences.
ª2014 Production and hosting by Elsevier B.V. on behalf of National Institute of Oceanography and
Fisheries.
Introduction
Oysters are marine animals belonging to the family Ostreidae.
They are one of the best known and most widely cultivated
marine animals. Oysters are highly esteemed sea food and
considered a delicacy in USA, Europe, Japan etc. In India till
recently oysters were consumed in the coastal areas only,
mainly by fisherfolk and a few others to a limited extent.
However, with the growing awareness for more nutritious
food, demand for oyster meat has risen in the country among
all classes of people. Yet there are places in Maharashtra, Goa
*Corresponding author. Tel.: +91 4842666845x305.
E-mail address: asha.santhosh5@gmail.com (K.K. Asha).
Peer review under responsibility of National Institute of Oceanography
and Fisheries.
Production and hosting by Elsevier
Egyptian Journal of Aquatic Research (2014) xxx, xxx–xxx
National Institute of Oceanography and Fisheries
Egyptian Journal of Aquatic Research
http://ees.elsevier.com/ejar
www.sciencedirect.com
1687-4285 ª2014 Production and hosting by Elsevier B.V. on behalf of National Institute of Oceanography and Fisheries.
http://dx.doi.org/10.1016/j.ejar.2014.02.001
Please cite this article in press as: Asha, K.K. et al., Biochemical profile of oyster Crassostrea madrasensis and its nutritional attributes. Egyptian
Journal of Aquatic Research (2014), http://dx.doi.org/10.1016/j.ejar.2014.02.001

and Karnataka on the west coast and Tamil Nadu, Pondicher-
ry and Andhra Pradesh along the east coast with rich bivalve
resources but their utilisation for human consumption is very
negligible (Kripa and Appukuttan, 2003). The resources in
these places are fished mainly for use in the construction
industry for the manufacture of cement, calcium carbide,
sand–lime bricks and lime. Ironically nutrition-rich oyster
meat is discarded and the shell is used in these industries.
Six species of oysters namely the Indian backwater oyster
Crassostrea madrasensis, Chinese oyster, Crassostrea rivularis,
West coast oyster, Crassostrea gryphoides, Indian rock oyster,
Saccostrea cucullata, Bombay Oyster, Saxostrea cucullata, and
giant oyster Hyostissa hyotis are found in India (James, 1992).
The first four species mentioned above are of commercial
value. Of the six species of oysters, the Indian backwater oys-
ter C. madrasensis is the dominant species, more widely dis-
tributed, is euryhaline and inhabits backwaters, creeks, bays
and lagoons and occurs in the coastal areas of the States of
Orissa, Andhra Pradesh, Tamil Nadu, Kerala, Karnataka
and the Andamans. C. madrasensis is the common backwater
oyster found in all estuaries and backwaters on the east-coast,
but is consumed mostly in the southern region on the west
coast. It occurs in abundance particularly in Ennore and
Pulikkat areas in Chennai, Sonapur in Orissa and the Vemba-
nad Lake in Kerala (James et al., 1993). Vast stretches of
backwaters, estuaries and bays present along the Indian coast
harbour a natural population of the oyster suggesting suitabil-
ity of the habitat for oyster culture. Being filter feeders, the
oyster converts primary production in water into nutritious
sea food. Culture of these species is being carried out in sev-
eral places in India. This paper describes profiling of its nutri-
tional attributes with emphasis on its protein content and
quality, with an aim to increase its popularity among consum-
ers. Data on its biochemical composition may also prove
important for future policy formulation for sustainable exploi-
tation of this species.
Materials and methods
Sample collection and preparation
Cultured oysters were harvested in live condition from Moot-
hakunnam in Ernakulam District of Kerala and depurated for
a few hours. They were transported to the laboratory under
iced condition in insulated styrofoam boxes and were thor-
oughly washed to remove slime and dirt. The surface water
was blotted with filter paper, edible meat was separated from
the shells and kept on ice for immediate use. The meat was
homogenised by mincing and proximate composition, amino
acid content, fatty acid content and mineral content were
determined. Also tissue cholesterol and taurine content were
estimated.
Chemicals
All reagents and solvents used in this investigation were of
analytical grade. Standards like cholesterol, fatty acid methyl
esters, amino acids, taurine, etc. were purchased from
Sigma–Aldrich GmbH (Steinheim, Germany).
Biochemical analysis
Moisture
All analyses (n= 6) were carried out in triplicate. Moisture of
the fish samples (10 g) was determined according to the AOAC
(2000) method by drying in an oven at 105 C(n= 6). Results
were expressed as percentage of wet weight.
Ash
Ash content was determined by heating the sample (5 g) for
12 h in a silica crucible in a furnace at 525 C(n= 6) accord-
ing to the AOAC (2000) method. Results were expressed as
percentage of wet weight. Minerals were assayed using the
AOAC method. Macro elements were determined by flame
photometry using working standards in the range of 10–
40 ppm for each element (Na, K and Ca). Trace metals were
determined by Varian Spectra-220 AA atomic absorption spec-
trophotometer. Samples were aspirated into the flame and the
corresponding absorption of the characteristic radiation by
each element was recorded. Values are expressed in ppm.
Protein
Total protein content in the homogenised samples (5 g) was
determined using the Kjeldahl method (6). Results were
expressed as percentage of wet weight (n= 6) basis.
Amino acids analysis
Total amino acid composition was determined following the
method of Ishida et al. (1981) using a Shimadzu chromato-
graph LC-10AT vp high performance liquid chromatography
(HPLC) equipped with an ion exchange column, quaternary
pump, a 20 ll injection valve and a fluorescence detector.
Mobile phase A contained sodium citrate and ethanol (pH
3.5) and B had sodium citrate and NaOH (pH 9.8). The flow
rate was constant at 0.4 ml/min, and the column temperature
was set at 60 C. The fluorescence excitation and emission
wavelengths were 340 and 450 nm, respectively. Samples were
hydrolysed in 6 N HCl in evacuated sealed tubes at 110 C for
24 h. After derivatisation by O-phthalaldehyde, amino acids
were identified and quantified by comparison of their retention
times with those of standards (Sigma). The results were
expressed in terms of g amino acid per 100 g of crude protein.
Taurine estimation
Taurine content was estimated by the method described above.
For the purpose of quantification, taurine standard was run
separately and results were expressed in terms of mg taurine
per g of tissue.
Nutritional parameters
Determination of nutritional parameters of oyster protein:
Nutritional parameters were determined on the basis of the
amino acid profile. Essential amino acid score was calculated:
mg of essential amino acid/100 mg of test protein/mg of that
amino acid/100 mg of FAO/WHO reference protein (Millward
and Rivers, 1986). Chemical score i.e., the ratio of a gram of
the limiting amino acid in oyster protein to the same amount
of the corresponding amino acid in a reference diet (e.g.,
2 K.K. Asha et al.
Please cite this article in press as: Asha, K.K. et al., Biochemical profile of oyster Crassostrea madrasensis and its nutritional attributes. Egyptian
Journal of Aquatic Research (2014), http://dx.doi.org/10.1016/j.ejar.2014.02.001

whole-egg protein) multiplied by 100; of oyster protein was cal-
culated using the FAO/WHO (1991) reference pattern. Protein
efficiency ratio (PER) was estimated according to the regression
equations developed by Alsmeyer et al. (1974) as given below:
0:08084 ðX7Þ0:1094 ð1Þ
where X7 = Thr + Val + Met + Ile + Leu + Phe + Lys
0:06320 ðX10Þ0:1539 ð2Þ
where X10 = X7 + His + Arg + Tyr
Essential amino acid index (EAAI) was calculated according
to Oser (1959) using as standard the amino acid composition of
the whole egg protein published by Cheftel et al. (1985). EAAI
is calculated using the ratio of the quantity of each essential
amino acid in oyster protein to the quantity of the same amino
acid in a reference protein and this ratio was multiplied by 100.
Next, the log 10 of each ratio was calculated and the mean of
the values is obtained. Finally the antilog of this mean was
obtained. Biological value was calculated according to Oser
(1959) cited by Mune et al. (2011) using the following equation:
BV ¼1:09 EAAI 11:7ð3Þ
By convention, the essential amino acid pattern (g AA/
100 g protein) for whole egg was used, which is: lysine (6.98),
methionine + cystine (5.79), threonine (5.12), isoleucine
(6.29), leucine (8.82), valine (6.85), phenylalanine + tyrosine
(9.89) and tryptophan (1.49).
Lipid extraction
The estimation of crude fat content was done by continuous
extraction of fat with petroleum ether according to AOAC
method (2000). Total lipids were extracted according to the
method of Folch et al. (1957), using chloroform/methanol
(2:1). Aliquots of the chloroform layer extract were evaporated
to dryness under nitrogen and the lipids were quantified
gravimetrically.
Cholesterol estimation
Cholesterol is estimated by the method of Rudel and Morris
(1973). Standard cholesterol in the range of 10–50 lg/ml is
taken to which ferric chloride and sulphuric acid are added
to develop colour. Absorbance is read at 560 nm and a stan-
dard curve is made. Cholesterol content in oyster meat is
extrapolated from the standard curve.
Fatty acid analysis
Fatty acids methyl esters (FAMEs) were obtained by the
method described by Metcalfe et al. (1966). A fraction of the
lipid extract was saponified with 0.5 N NaOH in methanol fol-
lowed by methylation in 14% boron trifluoride in methanol
(BF
3
/MeOH). The methylated sample was then extracted with
8mln-hexane. All of these reactions were performed in quadru-
plet for each sample. The resulting methyl esters were analysed
using an Agilent Gas chromatograph system 6890 N equipped
with a flame ionisation detector (FID), a splitless injector
and a polar fused silica capillary column (30 m \0.25 mm
i.d. \0.25 lm film thickness). The temperature of the injector
and the detector were 250 and 275 C, respectively. Helium
was used as a carrier gas with a flow rate of 1.5 ml/min. Peaks
were identified by comparison of their retention times with
FAMEs standards (Supelco).
Statistical analysis
Statistical analysis was performed using SPSS software, ver-
sion 10.0. Values for each parameter analysed are means of
triplicate determinations.
Results and discussion
Biochemical composition
Biochemical composition of a species helps to assess its nutri-
tional and edible value in terms of energy units. Moisture, pro-
tein, crude fat and ash content of C. madrasensis are given in
Table 1.C. madrasensis has revealed the following chemical
composition: water (82%), protein (10%), fat (3.25%), car-
bohydrate (3.2%) and ash (1.01%). The main constituent of
oyster flesh is water, which is tightly bound to the proteins
in the structure in such a way that it cannot readily be expelled
even under high pressure and is an index of freshness (Murray
and Burt, 2001). The high protein content and the less than
average lipid levels are similar to that found in species of fish.
Oyster meat contains good amount of carbohydrate unlike in
fin fish in which it is negligible. Several studies (Berthelin
et al., 2000; Bacca et al., 2005) have stated the importance of
the presence of glycogen in oysters which play an important
role at the time of spawning. The ash content in oyster is
slightly lower than in fish species. Oyster meat is rich in both
macro elements and trace metals (Table 2). Potassium rich
foods are considered to be healthy by convention (USDA,
2010) which is present in oyster in significantly high
proportions. Trace metals like Se, Cu, Zn, Mn and Fe act as
cofactors for enzymatic reactions in intermediary metabolism
(Flemming, 1989) and Fe is an integral part of haemoglobin
(Hb) which is essential for oxygenation–deoxygenation cycle
of Hb. Selenium has been associated with protection of body
tissues against oxidative stress, maintenance of defences
against infection, and modulation of growth and development
(Rayman, 2000). These minerals are present at significantly
high levels in C. madrasensis.
Amino acids analysis
Table 3 shows the amino acid profile of C. madrasensis.
Among essential amino acids, lysine (14.3 g%) content was
the highest followed by threonine (12.3 g%); aspartic acid
(11.8 g%) and histidine (7.7 g%) were present in high concen-
tration among the non-essential amino acids. Such results are
similar to that found by others authors (Murray and Burt,
Table 1 Proximate composition (% wet weight) of C.
madrasensis.
Parameters Wet tissue weight (%)
Moisture 82.64 ± 1.31
Protein 9.41 ± 0.85
Lipid 3.25 ± 0.32
Carbohydrate 3.2 ± 0.13
Ash 1.01 ± 0.06
Values expressed as means ± S.D.
Biochemical composition and nutritional attributes of Crassostrea madrasensis 3
Please cite this article in press as: Asha, K.K. et al., Biochemical profile of oyster Crassostrea madrasensis and its nutritional attributes. Egyptian
Journal of Aquatic Research (2014), http://dx.doi.org/10.1016/j.ejar.2014.02.001

1969; Chukwuemeka, 2008) in fin fish. The concentration of
lysine in oyster protein is 14.3 g per 100 g crude protein which
is significantly higher than the FAO/WHO recommended ref-
erence lysine standard value of 5.8 g per 100 g of dietary pro-
tein for a 2–5 year child. An abnormally high content of
leucine in a protein interferes with the balance of two amino
acids namely, isoleucine and threonine and additionally hin-
ders the absorption of isoleucine and tryptophan. Grain pro-
teins like those of sorghum and maize contain a high
proportion of leucine that becomes a precipitating factor for
the manifestation of pellagra in nutritionally challenged sub-
jects. Interestingly, in oyster meat, leucine is present at a low
concentration of 2 g per 100 g crude protein. Table 4 shows
the essential amino acid score (EAAS) of oyster protein. Valine
and leucine had the lowest score of 0.17 and 0.30, respectively,
while, threonine had the highest EAAS of 3.62 which implies
that oyster protein has less content of valine and leucine than
there is in FAO/WHO recommended protein pattern.
Chemical score is a value obtained by comparing the con-
tent of the most limiting amino acid in test protein with its con-
tent in reference egg protein. The chemical score obtained for
oyster protein (Table 5) was 17.1% and the most limiting
amino acid was valine (17.1%) and the 2nd limiting amino acid
was leucine (30.3%). The protein efficiency ratio (PER) in C.
madrasensis (3.49 and 3.92, Table 5) was significantly more
than that of fin fish (2.7) and better than that of egg protein
(3.0). EAAI of oyster protein was 120.2 which indicates that
it is of high quality with respect to the presence of essential
amino acids and is higher than that of fin fish (89.1) (Lim
and Sessa, 1995). Biological value is a parameter that describes
the excellence of a protein in terms of its essential amino acid
content which was 174 for oyster protein; significantly higher
than that of fin fish (83) (Ganoviak and Lipka, 1983;
Ababouch, 2005).
Taurine
The freely occurring b-sulphonic amino acid, taurine was
estimated using high performance liquid chromatography.
Table 2 Macro minerals and trace elements (ppm) in oyster, C. madrasensis.
Macro minerals Na (ppm) K (ppm) Ca (ppm) Mg (ppm)
1170 ± 21 975 ± 13 309 ± 9 270 ± 7
Trace minerals Mn (ppb) Cu (ppb) Zn (ppb) Fe (ppb) Cr (ppb) Se (ppb)
0.81 ± 0.0 14.7 ± 0.6 95.5 ± 2 33.3 ± 1.1 ND 2.4 ± 0.6
Values expressed as means ± S.D.
Table 3 Amino acids profile (g/100 g crude
protein) of oyster, C. madrasensis.
Amino acid g/100 g
Asp 11.8
Thr 12.3
Ser 10.6
Glu 0.73
Pro 1.03
Gly 2.3
Ala 5.3
Cys 0.9
Val 2.6
Met 4.7
Ile 4.5
Leu 2.0
Tyr 5.9
Phe 4.1
His 7.7
Lys 14.3
Arg 6.4
Try 2.17
Total 99.33
Values expressed as means of three
determinations.
Table 4 Essential amino acid scores of oyster, C. madrasensis
protein.
Essential amino acid Essential amino acid score
Lys 2.47
Met + Cys 1.88
Thr 3.62
Ile 1.61
Leu 0.30
Val 0.17
Phe + Tyr 1.59
Try 2.00
Values are average of three determinations.
Table 5 Nutritional parameters of oyster, C. madrasensis protein.
Chemical score Limiting amino acids PER
c
EAAI Biological value
Lowest 2nd lowest
a
PER
1b
PER
2
C. madrasensis protein 17.1 Val (17.1%) Leu (30.3%) 3.49 3.92 120.2 174
Values are average of three determinations.
a
PER
1
(Protein efficiency ratio): 0.08084 (X7) -0.1094, X7 = Thr + Val + Met + Ile + Leu + Phe + Lys.
b
PER
2
: 0.06320 (X10) -0.1539, X10 = X7 + His + Arg + Tyr.
c
EAAI: Essential amino acid index.
4 K.K. Asha et al.
Please cite this article in press as: Asha, K.K. et al., Biochemical profile of oyster Crassostrea madrasensis and its nutritional attributes. Egyptian
Journal of Aquatic Research (2014), http://dx.doi.org/10.1016/j.ejar.2014.02.001

Figs. 1 and 2 show the chromatogram indicating the peak
and retention time of taurine standard and taurine content
in the oyster sample, respectively. The taurine content is
high in oyster meat 243 mg/100 g (Table 6) which is signifi-
cantly higher than that of fish 40–85 mg/100 g (Divakaran,
2006). The ratio of taurine to cholesterol is an important
index in foods and higher ratio is beneficial to the consumer
(Choi et al., 2006). Taurine:cholesterol ratio is 2.3 in oyster
(Table 6). Among taurine’s many natural functions in living
systems, is its hypocholesterolemic effect (Rijssenbeek et al.,
2006). Taurine acts by conjugating bile acids that are
formed from cholesterol synthesised in the liver and excret-
ing them through bile. To replenish the excreted bile acids
more endogenous cholesterol is converted to bile acids
which results in lowering of cholesterol in the body. Thus
taurine exhibits a hypolipidemic effect by stimulating hepatic
bile acid synthesis from endogenous stores of cholesterol
(Ogawa, 1996).
Figure 1 Chromatogram showing retention time and peak for standard taurine.
Figure 2 Chromatogram showing retention time and peak for taurine content in oyster meat.
Biochemical composition and nutritional attributes of Crassostrea madrasensis 5
Please cite this article in press as: Asha, K.K. et al., Biochemical profile of oyster Crassostrea madrasensis and its nutritional attributes. Egyptian
Journal of Aquatic Research (2014), http://dx.doi.org/10.1016/j.ejar.2014.02.001

Cholesterol
Cholesterol content in oyster is 106 mg/100 g (Table 6)of
oyster meat which is twice that of fish. The high cholesterol
content is compensated by the presence of high taurine content
in oyster as taurine is reported to have significant hypocholes-
terolemic effect.
Fatty acid analysis
Fatty acids composition of C. madrasensis is presented in
Table 7. Polyunsaturated fatty acids (PUFA) constitute the
majority of the fatty acids pool, followed by saturated fatty
acid (SFA) and monounsaturated fatty acids (MUFA). The
saturated fraction was 188.1 ± 4.85 mg/100 g with C20:0
being the most abundant fatty acid within this fraction, fol-
lowed by stearic acid C18:0 and palmitic acid C16:0. Among
mono-unsaturated fatty acids, C16:1 n-7 and C22:1 n-9 were
in abundance than any other fatty acids (28.0 ± 0.45 and
22.6 ± 0.56 mg/100 g, respectively). PUFA content was the
highest (261.58 ± 7.61 mg/100 g) of which n-3 PUFA was
214.9 ± 6.78 mg/100 g and n-6 PUFA was 46.08 ± 0.83 mg/
100 g. Eicosapentaenoic, docosahexaenoic and linoleic acids
were the prominent PUFA. The n-3/n-6 index was 4.66 which
shows the occurrence of a high proportion of n-3 PUFA over
n-6 PUFA in C. madrasensis. The ratio between n-3 and n-6 is
a very useful index for comparing the nutritional value of fish
lipid due to their human health effects on coronary heart dis-
ease, cancer and autoimmune diseases (Wang et al., 1990;
Simopoulos, 2002).
Conclusion
C. madrasensis is comparable to fin fish with respect to its nutri-
tional attributes with its protein being of high quality and its
lipids being a good source of n-3 and n-6 fatty acids. The high
levels of essential amino acids will make it a good food source in
complementing cereals for weaning foods. Their high utilisable
energy due to protein will prevent protein-energy malnutrition
in their consumers. Thus it might be considered as a kind of
aquatic food with high protein and low healthy fat. Biochemi-
cal composition and nutritional attributes of C. madrasensis
may prove important for formulations of nutraceuticals and
future policy regarding exploitation of this species.
Acknowledgements
The authors are grateful to the Director, CIFT for providing
permission to publish the paper. The assistance provided by
the technical personnel of B&N Division is gratefully
acknowledged.
References
Ababouch, L., 2005. Fisheries and aquaculture topics. Proteins from
fish and fish products. Topics fact sheets. In: FAO Fisheries and
Aquaculture Department, FAO, Rome. Available from: <http://
www.fao.org/fishery/topic/14869/en>.
Alsmeyer, R.H., Cunningham, A.E., Happich, M.L., 1974. Equations
predict PER from amino acid analysis. Food Technol. 28, 34–40.
AOAC, 2000. Official Methods of Analysis, 17th edition. AOAC
International, Gaithersburg, Maryland, USA.
Bacca, H., Huvet, A., Fabioux, C., Daniel, J.-Y., Delaporte, M.,
Pouvreau, S., Van Wormhoudt, A., Moal, J., 2005. Molecular
cloning and seasonal expression of oyster glycogen phosphorylase
and glycogen synthase genes. Comp. Biochem. Physiol. B 140, 635–
646.
Berthelin, C., Kellner, K., Mathieu, M., 2000. Storage metabolism in
the Pacific oyster (Crassostrea gigas) in relation to summer
mortalities and reproductive cycle (West Coast of France). Comp.
Biochem. Physiol. 125B, 359–369.
Table 7 Fatty acids composition (mg/100 g tissue) in oyster,
C. madrasensis.
Fatty acid mg/100 g oyster meat
c12:0 11.5 ± 0.21
c14:0 4.71 ± 0.04
c15:0 2.07 ± 0.29
c16:0 27.8 ± 0.03
c17:0 11.9 ± 0.22
c18:0 30.6 ± 1.4
c20:0 91.6 ± 2.6
c21:0 2.13 ± 0.01
c23:0 5.80 ± 0.05
c14:1 n-7 1.42 ± 0.02
c16:1 n-7 28.0 ± 0.45
c17:1 n-7 1.87 ± 0.06
c18:1 n-9 9.53 ± 0.09
c20:1 n-9 16.7 ± 0.32
c22:1 n-9 22.6 ± 0.56
c18:2 n-6 11.5 ± 0.27
c18:3 n-6 4.71 ± 0.07
c18:3 n-3 11.9 ± 0.18
c20:2 n-6 2.07 ± 0.06
c20:4 n-6 27.8 ± 0.43
c20:5 n-3 112.0 ± 3.7
c22:6 n-3 91.6 ± 2.9
PSFA
a
188.1 ± 4.85
PMUFA
b
80.12 ± 1.5
PPUFA
c
261.58 ± 7.61
Pn-6 FA
d
46.08 ± 0.83
Pn-3 FA
e
214.9 ± 6.78
n3/n6 4.66
Total FA 584.2 ± 13.96
Values expressed as mean (n= 6) ± S.D.
a
RSAT = sum percentage of saturated fatty acids (C12:0, C14:0,
C15:0, C16:0, C18:0, C20:0, C21:0, C23:0).
b
RMUFA = sum percentage of monounsaturated fatty acids
(C14:1, C16:1, C17:1, C18:1 n-9, C20:1, C22:1 n-9).
c
RPUFA = sum percentage of polyunsaturated fatty acids
(C18:2 n-6, C18:3 n-6, C18:3 n-3, C20:2 n-6, C20:4 n-6, C20:5 n-3,
C22:6 n-3).
d
Rn-6 = sum percentage of n-6 polyunsaturated fatty acids
(C18:2 n-6, C18:3 n-6, C20:4 n-6, C20:2 n-6).
e
Rn-3 = sum percentage of n-3 polyunsaturated fatty acids
(C18:3 n-3, C20:5 n-3, C22:6 n-3).
Table 6 Levels of taurine and cholesterol in oyster meat and
taurine/cholesterol ratio.
Taurine mg/100 g Cholesterol mg/100 g
Oyster 243 ± 3.5 106 ± 2.2
T:C
a
2.3
Values expressed as means ± S.D.
a
Taurine:cholesterol ratio.
6 K.K. Asha et al.
Please cite this article in press as: Asha, K.K. et al., Biochemical profile of oyster Crassostrea madrasensis and its nutritional attributes. Egyptian
Journal of Aquatic Research (2014), http://dx.doi.org/10.1016/j.ejar.2014.02.001

Cheftel, J.-C., Cuq, J.L., Lorient, D., 1985. Prote
´ines alimentaires.
Biochimie-proprie
´te
´s fonctionnellesvaleur nutritionnelle-modifica-
tions chimiques. Technique et documentation. Lavoisier, pp. 1–295.
Choi, M.-J., Kim, J.-H., Chang, K.J., 2006. In: Taurine 6: Advances in
Experimental Medicine and Biology: The Effect of Dietary Taurine
Supplementation on Plasma and Liver Lipid Concentrations and
Free Amino Acid Concentrations in Rats Fed a High-Cholesterol
Diet, vol. 583, pp. 235–242.
Chukwuemeka, U., 2008. The fatty and amino acids profiles of
Cichlidae and Claridae finfish species. Internet J. Food Safety 10,
18–25.
Dietary Guidelines for Americans, 2010. United States Department of
Agriculture, Center for Nutrition Policy and Promotion. National
Academy Press, Washington, DC.
Divakaran, S., 2006. Taurine: An amino acid rich in fish meal. In:
Suarez, L.E.C., Marie, D.R., Salazar, M.T., Lopez, M.G.N.,
Cavazos, D.A.V., Ortega, A.C.P. (Eds.), Avances en Nutricion
Aquicola VIII. VIII Simposium Internacional Nutricion Aquicola.
15–17 Noviembre. Universidad Autonoma de Nuevo Leon, Nuevo
Leon, Mexico, pp. 333–335.
FAO/WHO, 1991. Protein quality evaluation. In: Food and Agricul-
tural Organization of the United Nations, Rome, Italy.
Flemming, C.R., 1989. Trace element metabolism in adult patients
requiring total parenteral nutrition. Am. J. Clin. Nutr. 49, 573–579.
Folch, J., Lees, M., Sloane-Stanley, G.H., 1957. A simple method for
the isolation and purification of total lipids from animal tissues. J.
Biol. Chem. 226, 497–509.
Ganoviak, Z.M., Lipka, E.M., 1983. Biological value of protein from
raw fish and canned fish. Vopr. Pitan. 5, 46–51.
Ishida, Y., Fugita, T., Asai, K., 1981. New detection and separation
method for amino acid by high performance liquid chromatogra-
phy. J. Chromatogr. 204, 143–148.
James, P.S.B.R., 1992. The Indian edible oyster. In: Rengarajan, K.
(Ed.), Research Centre Central Marine Fisheries Research. St.
Francis Press, Cochin.
James, P.S.B.R., Narasimham, K.A., Satyanarayana, R.K., 1993.
Prospects for development of oyster culture in India. Mar. Fisheries
Inform. Serv. Tech. Extension Ser. 125, 1–3.
Kripa, V., Appukuttan, K.K., 2003. Marine bivalves. In: Mohan
Joseph, M., Jayaprakash, A.A. (Eds.), . In: Status of Exploited
Marine Fishery Resources of India, vol. 308. Central Marine
Fisheries Research Institute, Kochi, pp. 211–220.
Lim, C.E., Sessa, D.J., 1995. In: Nutrition and Utilization Technology
in Aquaculture. Amer Oil Chemists Society, p. 294. Available from:
http://books.google.co.in/books?id=NDEsPP30bfwC.
Metcalfe, L.D., Schimitz, A.A., Pelka, J.R., 1966. Rapid preparation
of fatty acids esters from lipids for gas chromatographic analysis.
Annexe Chem. 38, 524–535.
Millward, D.J., Rivers, J.P.W., 1986. Protein and amino acid
requirements in the adult human. J. Nutr. 116, 255–261.
Murray, J., Burt, J.R., 1969. The composition of fish. Torry Advis.
Note 38, Torry Research Station, Aberdeen.
Murray, J., Burt, J.R., 2001. The Composition of Fish. Ministry of
Technology, Torry Research Station. Available from: <http://
www.fao.org/wairdocs/tan/x5916E/x5916e00.HTM>.
Mune Mune, M.A., Minka, S.R., Mbome, I.L., Etoa, F.X., 2011.
Nutritional potential of bambara bean protein concentrate. Paki-
stan J. Nutr. 10, 112–119.
Ogawa, H., 1996. Effect of dietary taurine on lipid metabolism in
normocholeterolemic and hyoercholesterolemic stroke prone spon-
taneously hypersensitive rats. In: Huxtable, R.J., Azuma, J.,
Kuriyama, K., Nakagawa, M., Baba, A. (Eds.), . In: Advances in
Experimental Biology, Taurine 2. Basic and Clinical Aspects, vol.
403. Plenum Press, NY, pp. 107–115.
Oser, B.L., 1959. An integrated essential amino acid index for
predicting the biological value of proteins. In: Albanese, A.A.
(Ed.), Protein and Amino acid Nutrition. Academic Press, New
York, pp. 295–311.
Rayman, M.P., 2000. The importance of selenium to human health.
Lancet 356, 233–241.
Rijssenbeek, A.L., Melis, G.C., Oosterling, S.J., Boelens, P.G.,
Houdijk, A.P.J., Richir, M.C., van Leeuwen, P., 2006. Taurine
and the relevance of supplementation in humans, in health and
disease. Curr. Nutr. Food Sci. 2, 381–388.
Rudel, L.L., Morris, M.D., 1973. Determination of cholesterol using
ophtalaldehyde. J. Lipid Res. 14, 364–366.
Simopoulos, A.P., 2002. The importance of the ratio of omega-6/
omega-3 essential fatty acids. Biomed. Pharmacother. 56, 365–379.
Wang, Y.J., Miller, L.A., Perren, M., Addis, P.B., 1990. Omega-3 fatty
acids in Lake Superior fish. J. Food Sci. 55, 71–73.
Biochemical composition and nutritional attributes of Crassostrea madrasensis 7
Please cite this article in press as: Asha, K.K. et al., Biochemical profile of oyster Crassostrea madrasensis and its nutritional attributes. Egyptian
Journal of Aquatic Research (2014), http://dx.doi.org/10.1016/j.ejar.2014.02.001