Journal of Aquatic Food Product Technology, 20:233–246, 2011Copyright © Taylor & Francis Group, LLCISSN: 1049-8850 print / 1547-0636 onlineDOI: 10.1080/10498850.2011.560365

Seasonal Variations in Proximate and Fatty AcidComposition of Viscera of Sardinella aurita, Sarpa

salpa, and Sepia officinalis from Tunisia

MOHAMED KACEM,1 MOHAMED SELLAMI,1 WASSIMKAMMOUN,2 FAKHER FRIKHA,1 NABIL MILED,1 ANDFAOUZI BEN REBAH2

1Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS, Sfax,Tunisia2Institut National des Sciences et Technologies de la Mer, Sfax, Tunisia

Seasonal variations of the proximate composition and fatty acid profiles in viscera fromSardinella aurita, Sarpa salpa, and Sepia officinalis were studied. Significant seasonalvariations were observed in the amounts of moisture, lipid, protein, and ash betweenspecies. Viscera protein content undergoes large fluctuations. This tendency is differentfrom results observed for the edible parts or for the whole body of many marine species.Ash content also showed significant differences. Lipid contents varied with seasons, ina proportionally inverse manner to water contents. Fatty acid composition showed sig-nificant differences from October to December. Interestingly, the highest total omega-3contents were comparable to many commercial marine fish oils.

Keywords Sardinella aurita, Sarpa salpa, Sepia officinalis, proximate composition,fish oil, PUFAs, omega-3 fatty acids

Introduction

Fish processing industries generate large amounts of waste material including viscera,which represent an important part of the animal mass (about 15 to 25% of the originalcatch depending on the season; Kechaou et al., 2009). The disposal and/or utilization ofthese wastes represent environmental and health problems. However, this material can be avaluable bioresource from which waste represents an important commercial loss. Recently,many alternative methods of fish viscera processing have been examined including enzymeextraction (Kishimura et al., 2006; Kurtovic et al., 2006; Bougatef et al., 2007; Klomklaoet al., 2007; Klomklao et al., 2009; Aryee et al., 2009; Castillo-Yañez et al., 2009) andpreparation of protein hydrolysates, utilizable as feed in aquaculture diets (Wang et al.,2008) or for microbial growth (Aspmo et al., 2005; Horn et al., 2007; Vázquez et al., 2008).Fish wastes also have great potential to be used in producing peptides with biologicalproperties beneficial for human health (Bougatef et al., 2010). Moreover, lipids in vis-cera represent a potential valuable fraction with several beneficial health effects (Dyerberget al., 1978; Lee et al., 1994; Vanschoonbeek et al., 2003; Kechaou et al., 2009). A potential

Mohamed Sellami and Mohamed Kacem have participated equally to this work.Address correspondence to Faouzi Ben Rebah, Institut National des Sciences et Technologies

de la Mer, Sfax B. P. 1035, Sfax 3018, Tunisia. E-mail: benrebahf@yahoo.fr

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234 M. Kacem et al.

problem for exploiting fish viscera in producing value-added products concerns the varia-tion in the raw material composition, which may result in variations in the quality of theresulting products (Horn et al., 2007). However, most of the analytical surveys studyingfish composition have been focused on variations within the most traditionally profitablefractions such as the fillet, muscle, and liver (Beltran and Moral, 1991; Rajasilta, 1992;Bandarra et al., 1997; Aidos et al., 2002; Kandemir and Polat, 2007). Few data dealingwith viscera composition are available. In Tunisia, fish viscera represent abundant fish-ery by-products that are not until now utilized. In order to exploit this biomass, knowledgeabout the possible variations in the biochemical composition is needed. Hence, the purposeof this study was to determine the biochemical composition of viscera of three Tunisianmarine species (Sardinella aurita, Sarpa salpa, and Sepia officinalis) caught in the Gulf ofGabès area (Tunisia). The fatty acid profile was also investigated.

Materials and Methods

Biological Materials

Biological material was viscera from sardinelle (Sardinella aurita), salema (Sarpa salpa),and cuttlefish (Sepia officinalis) caught in the Gabès Gulf of Tunisia during the period2008–2009. Sepia officinalis viscera were provided by Calembo, a seafood processingindustry located in Sfax region (Tunisia). Fish (Sardinella aurita and Sarpa salpa) werepurchased from the local market of Sfax city. Two to 3 kg of fresh fish species werewashed with water, then viscera were separated and used to determine the biochemicalcomposition. The viscera fraction included stomach, intestines, and pyloric caeca.

Chemical Analysis

Viscera were homogenized by a meat grinder and used to determine the chemical compo-sition. According to the AOAC (1990) methods, water content was quantified by dryingsamples at 100◦C until the weight was constant, lipid by Soxhlet extraction, proteins byKjeldahl procedure, and ash by incineration in a muffle furnace at 550◦C (for 1 h). Theseanalyses were performed from October 2008 to May 2009.

In order to determine fatty acid composition, homogenized samples of viscera (sam-ples of October and December 2008) were extracted using methanol/chloroform (2:1 v/v)method. Fatty acid methyl esters (FAMEs) were prepared according to Slover and Lanza(1979). The determination of fatty acids was conducted using Shimadzu gas chromatog-raphy (GC- 2010) equipped with flame ionization detector and DB-wax capillary column(length 30 m × internal diameter 0.32 mm, Agilent, J and W Scientific, Folsom, CA, USA).Nitrogen was used as carrier gas at a flow rate of 4 mL/min. The temperatures of the injec-tor port and detector were held at 200 and 240◦C, respectively. The initial temperature ofthe column was held at 100◦C, then increased at a rate of 5◦C/min before being maintainedat 230◦C for 10 min. Identification was made by comparison of retention times with thoseof standard FAMEs.

Statistical Analysis

Data were subjected to Student’s t-test to determine whether there is significant differencebetween means at the 5% level of probability or not. Values are expressed as means ofthree replicates ± SEM (standard error of mean).

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Chemical Composition of Marine Species’ Viscera 235

Results

Proximate Composition

The water, total lipid, crude protein, and ash contents of three marine species’ visceraare illustrated in Figures 1–4. For Sardinella aurita viscera, the moisture content over theyear ranged from 49.06 ± 0.06% in November to 78.15 ± 0.91% in May with significantdifferences (p < 0.05). From October to December, the moisture value remained almostconstant, and a significant enhancement was observed in January (p < 0.05). However,the moisture declined during the period of February to March and increased again fromMarch to April (Figure 1A). In the cases of Sarpa salpa and Sepia officinalis, water contentvaried slightly from 83.37 ± 0.09 to 89 ± 0.07% and from 75 ± 0.67 to 85.04 ± 0.14%,

40

50

60

70

80

90

Oct

ober

Nov

embe

r

Dec

embe

r

Janu

ary

Feb

ruar

y

Mar

ch

Apr

il

May

Wat

er (

%)

Sarpa salpa

Sardinella aurita

Sepia officinalis (A)

0Sarpa salpa Sepiao cinalisSardinella aurita

20

40

60

80

100

Wat

er (

%)

(B)

Figure 1. Water contents of Sardinella aurita, Sarpa salpa, and Sepia officinalis viscera (A) seasonalvariation (B) mean values over the period of sampling.

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236 M. Kacem et al.

0

5

10

15

20

25

Oct

ober

Nov

embe

r

Dec

embe

r

Janu

ary

Feb

ruar

y

Mar

ch

Apr

il

May

Lip

ids

(%)

Sarpa salpaSardinella auritaSepia officinalis

(A)

0Sarpa salpa Sepia officinalisSardinella aurita

4

8

12

16

20

24

28

Lip

ids

(%)

(B)

Figure 2. Lipid contents of Sardinella aurita, Sarpa salpa, and Sepia officinalis viscera (A) seasonalvariation (B) mean values over the period of sampling.

respectively. As indicated in Figure 1B, the mean values of water content over the period ofsampling showed the lowest value for Sardinella aurita viscera (61.96 ± 12.31%); whereasthe highest mean values were 81.60 ± 2.07 and 87.34 ± 1.72% for Sepia officinalis andSarpa salpa viscera, respectively.

Lipid content varied with seasons in a proportionally inverse manner to water content(Figure 2A). For Sardinella aurita viscera, lipid content varied significantly over the yearwith a minimum in May (3.90 ± 0.28%) and a maximum in November (25.40 ± 0.16%).For Sepia officinalis and Sarpa salpa viscera, lipid content varied from 0.58 ± 0.30 to4.02 ± 0.14% and from 0.36 ± 0.16 to 3.63 ± 0.16%, respectively. Interestingly, Sardinellaaurita viscera displayed the highest lipid content mean value along the sampling period(Figure 2B).

For all species, protein content varied significantly over the year. For Sardinella auritaviscera, significant (p < 0.05) variations ranging from 1.36 ± 0.15% (obtained in October)to 15.88 ± 0.88% (obtained in May) were observed. For Sepia officinalis and Sarpa salpaviscera, protein content also varied significantly (p < 0.05) from 7.71 ± 0.10% (in March)to 13.49 ± 0.41% (in October) and from 3.83 ± 0.27% (in December) to 6.65 ± 0.11%

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Chemical Composition of Marine Species’ Viscera 237

0

4

8

12

16

Oct

ober

Nov

embe

r

Dec

embe

r

Janu

ary

Feb

ruar

y

Mar

ch

Apr

il

May

Pro

tein

s (%

)

(A)

0

5

10

15

Pro

tein

s (%

)

(B)

Sarpa salpaSepia officinalis Sardinella aurita

Sarpa salpaSardinella auritaSepia officinalis

Figure 3. Protein contents of Sardinella aurita, Sarpa salpa, and Sepia officinalis viscera (A)seasonal variation (B) mean values over the period of sampling.

(in February), respectively. According to Figure 3B, the highest mean value of proteincontent over the sampling period was observed for Sepia officinalis (10.08 ± 1.21%).

For ash content (Figure 4A), all samples showed remarkable changes over the year.Sepia officinalis viscera had the largest ash content variation, ranging from 2.32 ± 0.00%(obtained in December) to 6.17 ± 0.05% (obtained in November) with significant dif-ferences (p < 0.05). However, Sardinella aurita and Sarpa salpa viscera displayedlower variations ranging from 1.33 ± 0.05 to 2.78 ± 0.04% and from 1.31 ± 0.07 to3.48 ± 0.05%, respectively. The highest ash content mean value over the sampling periodwas observed for Sepia officinalis (4.71 ± 0.88%; Figure 4B).

Fatty Acid Composition

Analysis of lipids from the three marine species viscera showed significant differ-ences in fatty acid composition from October to December (p < 0.05). The fatty acid

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238 M. Kacem et al.

0

1

2

3

4

5

6

Ash

(%

)

(B)

Sarpa salpa Sepia officinalisSardinella aurita

0

2

4

6

Oct

ober

Nov

embe

r

Dec

embe

r

Janu

ary

Feb

ruar

y

Mar

ch

Apr

il

May

Ash

(%

)

(A)Sarpa salpaSardinella auritaSepia officinalis

Figure 4. Ash contents of Sardinella aurita, Sarpa salpa, and Sepia officinalis viscera (A) seasonalvariation (B) mean values over the period of sampling.

profile exhibited a dominance of saturated fatty acids (SFAs), except the sample ofDecember from Sepia officinalis which showed the dominance of the polyunsaturated fattyacids (PUFAs). For all samples, fatty acid compositions were as follows: 29.41–58.03%SFAs, 12.08–28.83% monounsaturated fatty acids (MUFAs), and 14.04–44.05% PUFAs(Table 1).

The most abundant individual fatty acids were lauric acid (C12:0), palmitic acid(C16:0), palmitoleic acid (C16:1 n-7), eicosapentaenoic acid (EPA, 20:5 n-3), and docosa-hexaenoic acid (DHA, C22:6 n-3) in lipids from Sardinella aurita viscera. For Sarpa salpaviscera, myristic acid (C14:0), C16:0, stearic acid (C18:0), eicosenoic acid (C20:1 n-9),and adrenic acid (C22:4 n-6) were the most abundant. However, only C16:0, oleic acid(C18:1 n-9), arachidonic acid (C20:4 n-6), and EPA were found in Sepia officinalissamples.

SFA chain length ranged from 10 (capric acid; C10:0) to 24 (lignoceric acid; C24:0)in most samples. C16:0 was generally the most abundant saturated fatty acid with con-tents ranging from 10.88 ± 1.01% (obtained in December for Sarpa salpa viscera) to28.04±0.92% (obtained in December for Sardinella aurita viscera). Among the SFAs, thoseoccurring at high proportions were C12:0 (up to 9.00% notified in October and December

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Tabl

e1

Seas

onal

vari

atio

nof

fatty

acid

cont

ento

fvi

scer

afr

omSa

rdin

ella

auri

ta,S

arpa

salp

a,an

dSe

pia

offic

inal

is(s

ampl

esof

Oct

ober

and

Dec

embe

r20

08,%

wto

fto

talf

atty

acid

s)

Spec

ies

Sard

inel

laau

rita

Sarp

asa

lpa

Sepi

aof

ficin

alis

Fatty

acid

sO

ctob

erD

ecem

ber

Oct

ober

Dec

embe

rO

ctob

erD

ecem

ber

Satu

rate

dfa

tty

acid

s(S

FAs)

%C

10:0

0.11

±0.

000.

08±

0.01

0.23

±0.

001.

23±

0.23

nd0.

22±

0.02

C12

:09.

26±

0.59

10.9

4±

1.99

5.50

±0.

741.

19±

0.03

1.24

±0.

711.

64±

0.18

C14

:00.

72±

0.10

1.68

±0.

310.

51±

0.01

nd0.

87±

0.07

0.45

±0.

00C

16:0

25.7

2±

1.04

28.0

4±

0.92

37.0

7±

2.68

10.8

8±

1.01

21.5

3±

1.33

13.4

2±

2.23

C17

:02.

13±

0.51

2.40

±1.

351.

14±

0.00

nd1.

97±

0.87

1.34

±0.

00C

18:0

2.32

±1.

653.

18±

2.99

11.7

2±

0.74

9.05

±1.

0112

.29

±2.

554.

80±

0.53

C20

:01.

60±

0.27

1.40

±0.

100.

85±

0.18

2.25

±0.

324.

46±

0.97

1.95

±0.

49C

23:0

0.54

±0.

270.

35±

0.08

nd14

.06

±1.

86nd

ndC

24:0

0.81

±0.

420.

80±

0.22

1.01

±0.

024.

62±

0.04

0.63

±0.

065.

60±

1.44

∑SF

As

43.2

148

.88

58.0

343

.28

43.0

029

.41

Mon

ouns

atur

ated

fatt

yac

ids

(MU

FAs)

%C

16:1

n-7

16.1

4±

0.06

6.88

±1.

345.

46±

0.60

1.41

±0.

375.

08±

1.19

6.71

±0.

77C

17:1

nd0.

41±

0.22

0.94

±0.

00nd

ndnd

C18

:1n-

94.

67±

1.96

5.06

±2.

2320

.97

±0.

062.

15±

0.27

5.34

±0.

209.

70±

2.82

C18

:1n-

73.

96±

0.25

2.83

±2.

74nd

1.44

±0.

382.

30±

0.32

4.75

±0.

32C

20:1

n-9

1.09

±0.

211.

47±

0.02

1.47

±0.

227.

09±

1.78

9.05

±1.

133.

58±

0.82

∑M

UFA

s25

.86

16.6

528

.83

12.0

821

.78

24.7

5

Poly

unsa

tura

ted

fatt

yac

ids

(PU

FAs)

%C

16:2

n-6

nd0.

88±

0.19

nd0.

95±

0.40

ndnd

C16

:3n-

41.

56±

0.05

0.44

±0.

37nd

ndnd

nd

(Con

tinu

ed)

239

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Tabl

e1

(Con

tinue

d)

Spec

ies

Sard

inel

laau

rita

Sarp

asa

lpa

Sepi

aof

ficin

alis

Fatty

acid

sO

ctob

erD

ecem

ber

Oct

ober

Dec

embe

rO

ctob

erD

ecem

ber

C16

:4n-

32.

27±

0.00

1.99

±0.

60nd

1.80

±0.

141.

98±

0.32

1.14

±0.

23C

18:2

n-7

ndnd

ndnd

2.30

±0.

32nd

C18

:2n-

61.

62±

0.07

1.22

±0.

474.

57±

0,30

1.84

±0.

192.

02±

0.43

3.54

±0.

21C

18:3

n-3

1.19

±0.

001.

75±

1.04

1.11

±0.

00nd

1.05

±0.

871.

38±

0.44

C18

:4n-

30.

61±

0.00

0.25

±0.

123.

99±

0.00

2.56

±0.

372.

16±

0.00

2.87

±0.

12C

20:2

n-6

0.80

±0.

160.

25±

0.00

ndnd

nd2.

35±

1.45

C20

:3n-

3nd

0.21

±0.

18nd

2.54

±0.

10nd

1.12

±0.

36C

20:4

n-6

1.65

±0.

341.

28±

0.22

0.91

±0.

193.

71±

0.17

4.81

±0.

279.

49±

0.03

C20

:5n-

38.

42±

0.43

7.40

±0.

962.

04±

0.67

4.13

±0.

367.

09±

1.77

11.5

8±

0.34

C22

:4n-

6nd

0.26

±0.

000.

57±

0.07

7.97

±3.

752.

13±

0.12

2.63

±0.

13C

22:5

n-3

0.65

±0.

420.

93±

0.03

nd3.

37±

0,03

nd1.

62±

0.13

C22

:6n-

33.

75±

0.83

13.5

9±

0.25

0.85

±0.

135.

97±

0.53

9.14

±1.

386.

34±

0.40

∑PU

FAs

22.5

030

.46

14.0

434

.84

29.3

044

.05

∑ω

-3FA

s18

.54

26.1

29.

4720

.37

21.4

226

.05

Val

ues

are

expr

esse

das

mea

n±

SEM

;ω-3

FAs:

omeg

a-3

fatty

acid

s.

240

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Chemical Composition of Marine Species’ Viscera 241

samples from Sardinella aurita viscera) and C18:0 (reached 11.72 ± 0.74 and12.29 ± 2.55% in October for Sarpa salpa and Sepia officinalis viscera, respectively).The tricosanoic acid (C23:0) was also found at a high proportion only in the Octobersample from Sarpa salpa (14.06 ± 1.86%). For MUFAs, the most abundant fatty acidobserved in samples from Sardinella aurita viscera was C16:1 n-7 with a content varyingfrom 6.88 ± 1.34% (in December) to 16.14 ± 0.06% (in October). The highest contentin C18:1 n-9 was observed for Sarpa salpa sample during October (20.97 ± 0.06%).However, in the case of Sepia officinalis, the most abundant MUFAs were C18:1 n-9and C20:1 n-9 which contents reached in December 9.70 ± 2.82 and 9.05 ± 1.13%,respectively.

Among the PUFAs, EPA (7.04 ± 0.96–8.42 ± 0.43%) and DHA (3.75 ±0.83–13.59 ± 0.25%) were the major fatty acids in the lipidic fraction from Sardinellaaurita viscera. These two fatty acids were found at high proportions in Sepia officinalisviscera oil with maximum contents of 11.58 ± 0.34% (in December) and 9.14 ± 1.38%(in October) for EPA and DHA, respectively. For the samples from Sarpa salpa viscera,the most abundant fatty acids were EPA (4.13 ± 0.36%), DHA (5.97 ± 0.53%), andC22: 4 n-6 (7.97 ± 3.75%) observed during December.

Discussion

The proximate composition of viscera from three marine species (Sardinella aurita, Sarpasalpa, and Sepia officinalis) was investigated. We have observed seasonal variations in themoisture, lipid, protein, and ash contents in response to various factors. Commonly, thevariation of the chemical composition has been described for different fish species andwas reported to be related to many factors such as season, temperature, location, breedingcycle, diet, age, size, and sex (Rajasilta, 1992; Bandarra et al., 1997).

The protein content of viscera undergoes large fluctuations among the studied marineorganisms and over the period of sampling, with significant differences (p < 0.05). Thistendency is different from results obtained for the edible parts or for the whole body ofmany marine species. For example, for the entire body of Sardinella aurita, protein contentremains constant at a high level over the year (Ben Rebah et al., 2009). Furthermore, it wasreported that fish protein content changes very little with season (Emokpae, 1983; Njinkoueet al., 2002; Tzikas et al., 2007). As observed for proteins, ash content also showed sig-nificant differences (p < 0.05) for all samples (ranged from 1.31 to 6.16%). Likewise, thetotal lipid contents of Sardinella aurita, Sarpa salpa, and Sepia officinalis viscera showedwide variations with seasons. This tendency was clear for Sardinella aurita viscera whoselipid content ranged between 3.90 and 25.40%. For all samples, lipid content varied ininverse proportions to water content. This fact was widely recognized in many pelagicfishes (Méndez and González, 1997; Grigorakis et al., 2002; Love, 1980). For example,in the case of Sardinella aurita viscera, lower lipid content (3.90%) and higher moisture(78.15%) were observed in May. A similar tendency was reported by Ben Rebah et al.(2009) for the entire body of Sardinella aurita indicating the fact that during the warmseason, lipid contents decreased considerably dropping to 2.50% in July (Ben Rebah et al.,2009). For Sarpa salpa and Sepia officinalis viscera, lipid contents did not exceed 5%.These low values could be explained by the fact that lipids accumulate in other organssuch as liver, as reported for many marine species (Njinkoue et al., 2002; Ben Rebah et al.,2009). In our study, Sepia officinalis viscera lipid contents were higher than those reportedfor the cuttlefish mantle (lower than 1% over the year; Ozyurt et al., 2006). Generally, lipidand water contents are closely related to the growth and the reproduction patterns (degree

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242 M. Kacem et al.

of maturity of gonads) of each species, as well as their exploitation in food resources,which are highly influenced by the dynamics of upwelling systems (Rajasilta, 1992).

It is very important to indicate the fact that the proximate composition of vis-cera is influenced by previous nutritional history. This makes it difficult to compare thecomposition between viscera. Hence, under natural conditions, Sarpa salpa is mostlyherbivorous, changing its food habit by the age and flesh chemistry (Gerking, 1984;Havelange et al., 1997). For Sepia officinalis, food consists of small molluscs, crabs,shrimps, other cuttlefishes, and juvenile fishes (Guerra, 1985; Castro and Guerra, 1989).However, Sardinella aurita feeds mainly on zooplankton, especially copepods and somephytoplankton (Tsikliras et al., 2005).

Concerning the fatty acid profiles, the composition varied with seasons among thestudied marine organisms. These results are in line with other studies dealing with vis-cera or with the edible parts of fish (Falch et al., 2006; Kandemir and Polat, 2007; BenRebah et al., 2009). For almost all samples, C16:0 was reported as the most abundant fattyacid for both October and December. These results are in agreement with other studieson Mediterranean fishes (Karakoltsidis et al., 1995; Saglik and Imre, 2001; Zlatanos andLaskaridis, 2007; Ben Rebah et al., 2009). In fact, palmitic acid is the key metabolite infish (Andrade et al., 1995). However, apart from C16:0, the fatty acids reported to havethe highest percentages vary among the studied species. This variability suggests differentbiological functions in fishes for the various fatty acids (Zlatanos and Laskaridis, 2007).

Generally, the amount and type of fatty acids in viscera differ slightly from thoseobtained for the edible parts or for the entire organisms (Table 2). For example, comparedto viscera, the entire Sardinella aurita fish (captured in February) contains higher concen-trations of C16:0, C16:1 n-7, C20:5 n-3, C22:6 n-3, and C14:0 and lower concentration ofC12:0 (Ben Rebah et al., 2009). For Sepia officinalis, the major fatty acids in viscera wereC16:0, C18:0, C20:5 n-3, and C22:6 n-3, which are similar to those reported for the man-tle of cuttlefish captured from the Northeastern Mediterranean. However, the proportionsof SFAs, MUFAs, and PUFAs in mantle were found to display differences as comparedto viscera (Ozyurt et al., 2006). Therefore, fatty acid profiles in various organs of marineorganisms could be controlled by many factors (sex, size, age, reproduction, water tem-perature, degree of pollution, nutritional condition, genetic differences between species,geographical location, handling, processing, storage, and distribution; Pigott and Tucker,1987; Luzia et al., 2003; Ozyurt et al., 2006; Sun et al., 2006; Kandemir and Polat, 2007).

The percentages of PUFAs found in viscera of the three marine organisms were impor-tant. The highest levels of PUFAs were observed for Sepia officinalis samples (rangingfrom 29.30 to 44.05%) with DHA and EPA being the major ones. For all samples, the totalomega-3 contents (ranged from 20.37 to 26.12% in December) were comparable to manycommercial marine fish oils such as that of Atlantic mackerel, Scomber scombrus (18.8%)and Japanese sardine, Sardinops melanosticta (25.9%; Ackman, 1990). Therefore, visceraseem to be a good source of omega-3 fatty acids recognized for their health benefits.

Conclusion

The study of the seasonal variation of the composition of viscera is important andmay provide information useful in the production of higher value-added products fromviscera—such as silage, hydrolysates, bioactive compounds, enzymes, and oil. This vari-ation could considerably affect the quality of the value-added product (Horn et al., 2007).Our results indicate that these marine by-products are interesting for the extraction of oilin view of commercial exploitation. One advantage of oil from viscera is that it is much

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Tabl

e2

Vis

cera

gene

ralf

atty

acid

sof

Sard

inel

laau

rita

,Sar

pasa

lpa,

and

Sepi

aof

ficin

alis

com

pare

dto

othe

rst

udie

s(%

wto

fto

talf

atty

acid

s)

Sard

inel

laau

rita

Sepi

aof

ficin

alis

Sarp

asa

lpa

Spec

ies

Vis

cera

Ent

ire

fish

Vis

cera

Man

tleV

isce

raM

uscl

e

Peri

odof

sam

plin

gO

ctob

er20

08;

Dec

embe

r200

8Fe

brua

ryO

ctob

er20

08;

Dec

embe

r200

8O

ver

the

year

Oct

ober

2008

;D

ecem

ber2

008

Ove

rth

eye

ar

Reg

ion

ofsa

mpl

ing

Gab

èsG

ulf,

Tun

isia

Gab

èsG

ulf,

Tun

isia

Gab

èsG

ulf,

Tun

isia

Nor

thea

ster

nM

edite

rran

ean

Gab

èsG

ulf,

Tun

isia

Spai

n

SFA

s43

.28;

48.8

837

.50

43.0

0;29

.41

29.5

–36.

8058

.03;

43.2

837

.50

MU

FAs

25.8

6;16

.65

21.2

021

.78;

24.7

57.

81–9

.85

28.8

3;12

.08

20.7

0PU

FAs

22.5

0;30

.46

31.6

029

.30;

44.0

543

.70–

49.6

14.0

4;34

.84

43.3

0ω

-3FA

s18

.54;

26.1

225

.00

21.4

2;26

.05

37.9

0–44

.50

9.47

;20.

3734

.30

Ref

eren

ces

Pres

ents

tudy

Ben

Reb

ahet

al.,

2009

Pres

ents

tudy

Ozy

urte

tal.,

2006

Pres

ents

tudy

Sori

guer

etal

.,19

97

SFA

s:sa

tura

ted

fatty

acid

s;M

UFA

s:m

onou

nsat

urat

edfa

ttyac

ids;

PUFA

s:po

lyun

satu

rate

dfa

ttyac

ids,

ω-3

FAs:

omeg

a-3

fatty

acid

s.

243

Downloaded By: [Ben Rebah, Faouzi] At: 15:01 13 April 2011

244 M. Kacem et al.

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