|40 YEARS AGO
|Year : 2015 | Volume
| Issue : 2 | Page : 91-94
Fatty acid saturation profiles and lipid contents of muscles from six popular culinary fish species sold in Umuahia, Nigeria
Chukwunonso ECC Ejike, Onyedikachi E Mbaraonye, Ebere R Enyinnaya
Department of Biochemistry, College of Natural Sciences, Michael Okpara University of Agriculture, Umudike, Umuahia, Abia, Nigeria
|Date of Web Publication||4-Aug-2015|
Chukwunonso ECC Ejike
Department of Biochemistry, College of Natural Sciences, Michael Okpara University of Agriculture, Umudike, PMB 7267, Umuahia, Abia 450 272
Source of Support: None, Conflict of Interest: None
Introduction: Fish oils, containing mainly poly-unsaturated fatty acids (PUFA), are reported to be nutri-medically beneficial. There is however little or no data on the lipid contents of, and fatty acids present in, culinary fish species consumed in Umuahia, Nigeria, hence this study.
Methods: The fatty acid saturation profiles and lipid contents of Scomberomorus maculatus (Mitchill, 1815), Micropogonias undulatus (Linnaeus 1766), Chrysichthys nigrodigitatus (Lacépède: 1803), Trichiurus japonicus (Temminck and Schlegel, 1844), Sardinella pilchardus (Walbaum, 1792), and Prochilodus lineatus (Valenciennes, 1836), all culinary fishes consumed in Umuahia were studied using standard procedures.
Results: C. nigrodigitatus had the highest crude lipid content (21.1 ± 1.1%) followed by S. pilchardus (20.4 ± 0.6%) and P. lineatus (20.1 ± 1.0%). S. maculatus and T. japonicus had the lowest crude lipid content (~13.3% each). PUFA were most abundant in S. maculatus (40.5 ± 0.4%) and T. japonicus (39.9 ± 0.5%), but least abundant in S. pilchardus and C. nigrodigitatus (~6.0% each). Linolenic and palmitic acids were the most abundant PUFA and saturated fatty acid, respectively, in the studied fish species.
Conclusion: S. maculatus and T. japonicus are the most nutri-medically desirable fishes of the six studied species.
Keywords: Culinary fish, fatty acids, fish oil, lipids, saturation
|How to cite this article:|
Ejike CE, Mbaraonye OE, Enyinnaya ER. Fatty acid saturation profiles and lipid contents of muscles from six popular culinary fish species sold in Umuahia, Nigeria. J Med Nutr Nutraceut 2015;4:91-4
|How to cite this URL:|
Ejike CE, Mbaraonye OE, Enyinnaya ER. Fatty acid saturation profiles and lipid contents of muscles from six popular culinary fish species sold in Umuahia, Nigeria. J Med Nutr Nutraceut [serial online] 2015 [cited 2019 Mar 22];4:91-4. Available from: http://www.jmnn.org/text.asp?2015/4/2/91/151807
| Introduction|| |
Fatty acids are the principal components of lipids. In fishes and other marine organisms, they are usually made up of chains of 14 to 24 carbon atoms with different degrees of saturation.  Fishes are integral components in the diet of most Nigerians and their consumption is increasing, probably due to a growing awareness of their beneficial effects coupled with an increase in the importation of exotic species. Fish oil consumption is reportedly associated with beneficial effects such as reductions in blood pressure and blood triacylglycerol (TAG)/TAG-rich lipoprotein concentrations, and lowering of cardiovascular disease (CVD) morbidity and mortality. , Poly-unsaturated fatty acids (PUFAs) in fish oil are thought to counter atherosclerotic vascular diseases through mechanisms related to lipid metabolism or others mediated through non-lipid mechanisms.  The fatty acid composition of fish oils are however known to be affected by species, environmental factors, size, age, and diets. ,
Consequently, this study was designed to assess the fatty acid saturation profiles of six fish species-Atlantic Spanish mackerel, Scomberomorus maculatus (Mitchill, 1815), Atlantic croaker, Micropogonias undulatus (Linnaeus 1766), silver catfish, Chrysichthys nigrodigitatus (Lacépède: 1803), Japanese horse mackerel, Trichiurus japonicus (Temminck and Schlegel, 1844), Sardine, Sardinella pilchardus (Walbaum, 1792), and Central and South American ray-finned sabalo, Prochilodus lineatus (Valenciennes, 1836)-sold in retail outlets in Umuahia, Abia State, Nigeria, and consumed widely by the population. The results are expected to inform choices for those who consume fish principally for the beneficial properties of fish oil.
| Materials and Methods|| |
Three samples each of Scomberomorus maculatus (Mitchill, 1815), Micropogonias undulatus (Linnaeus 1766), Chrysichthys nigrodigitatus (Lacépède: 1803), Trichiurus japonicus (Temminck and Schlegel, 1844), Sardinella pilchardus (Walbaum, 1792), and Prochilodus lineatus (Valenciennes, 1836) were purchased from retail outlets in Umuahia. The fishes were identified by experts at the Department of Fisheries and Aquatic Resources Management, Michael Okpara University of Agriculture, Umudike. Muscles from the fish were (each) carefully dissected out, washed and dried in an oven at 60°C. The dried samples were ground using a laboratory mill, and the lipids in each sample extracted using the Folch et al., method. The yields were determined gravimetrically and recorded as percent crude lipid content.
Fatty acid methyl esters (FAMEs) were prepared by transesterification of the fatty acids in the extracted lipid using 0.5 mol/L NaOH in methanol and 0.14 g/ml ethanolic boron trifluoride. The FAMEs were recovered with hexane, separated and measured in duplicates using a temperature-programed gas chromatograph. Individual fatty acids were identified by comparing the retention time of each FAME with that of a standard FAME mixture. Individual fatty acids are expressed as weight percent of total fatty acids.
From the values of the individual fatty acids, the percent concentration of saturated fatty acids (SFA), unsaturated fatty acids (UFA), mono-unsaturated fatty acids (MUFA), and poly-unsaturated fatty acids (PUFA) were computed. The results are presented as percentages (of the relevant totals), as mean ± standard deviation (SD) in bar charts.
| Results and Discussion|| |
C. nigrodigitatus gave the highest crude lipid yield (21.1 ± 1.1%), followed by S. pilchardus (20.4 ± 0.6%) and P. lineatus (20.1 ± 1.0%). S. maculatus and T. japonicus gave the lowest crude lipid yeild ( ̴ 13.3% each) [Figure 1]. S. pilchardus had the highest SFA content (54.8 ± 1.8%) while T. japonicus had the highest UFA content (63.1 ± 2.0%). MUFA were most abundant in P. lineatus (53.3 ± 1.0%). PUFA were most abundant in S. maculatus (40.5 ± 0.4%) and T. japonicus (39.9 ± 0.5%), but least abundant in S. pilchardus and C. nigrodigitatus ( ̴ 6.0% each) [Figure 2]. In T. japonicus and S. maculatus, linolenic acid was the most abundant PUFA. Oleic acid was the most abundant MUFA while palmitic acid was the most abundant SFA in all the studied species. Both oleic and palmitic acids were found most in C. nigrodigitatus relative to the other species.
|Figure 2: Saturated and unsaturated fatty acid contents of the studied fish species, SFA = saturated fatty acid, UFA = unsaturated fatty acid, MUFA = mono-unsaturated fatty acid, PUFA = poly-unsaturated fatty acid|
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The results of this study show that S. pilchardus and C. nigrodigitatus both have high lipid content [Table 1] and high SFA contents [Table 2], of the studied fish species, and may therefore not be nutri-medically desirable. Converely, S. maculatus and T. japonicus had the least lipid content, yet the most PUFA content and may be the most nutri-medically desirable of the studied species. Though fish oils are nutritionally and medically very desirable, SFA are not desirable due to their possible atherogenic and other harmful effects. The prevailing consensus among scientists is that fish oil consumption is beneficial even at modest levels of intake. The benefits derivable from such consumption are also known to be a function of the fatty acid saturation profile of the fish consumed.  The fish species with low lipid contents but high PUFA concentrations are therefore preferable for subjects seeking to derive health benefits from fish consumption.
|Table 2: Saturated and unsaturated fatty acid contents of the studied fish species |
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PUFA in fish oils are nutri-medically desirable because they lower the concentrations of endogenously derived triacylglycerol-rich lipoproteins, very-low-density lipoproteins (VLDLs), and intermediate-density lipoproteins. This, they achieve by (1) reducing VLDL triacylglycerol secretion;  (2) increasing VLDL apoliprotein B secretion;  (3) reducing triacylglycerol transport, and (4) increasing VLDL clearance.  These effects of PUFA are particularly prominent in hypertriglyceridemic subjects  and modestly observed in normotriglyceridemic subjects. It therefore suggests that consumption of S. maculatus and T. japonicusmay be particularly beneficial to subjects who have challenges with triacylglycerol metabolism.
It is important to note, however, that though the consumption of fish (and fish oil supplements) are generally well tolerated, side effects such as mild gastrointestinal discomfort, appearance of a fishy aftertaste, belching and flatulence, loose and oily stools, and nausea have been reported.  Again, fatty are rarely modified during digestion, absorption, and transport in the bloodstream. They are also taken up by tissues in their intact state. Thus, fatty acids in the fish diet can be deposited in the fish muscles with minimal modification in a predictable fashion. , Furthermore, as mentioned earlier, the fatty acid profile of fish oils are affected by species, environmental factors, size, and age. , These and the fact that animals are able to biosynthesize a relatively limited number of fatty acids implies that the fatty acids and the saturation profiles reported in the study may vary depending on how the above confounders play out in the fish species. A cautious interpretation of these findings is therefore warranted.
This study is limited by our inability to control for the above mentioned variables which affect the fatty acids present in fish. The effects of these factors may be attenuated by the fact that the fish species studied are farmed and harvested by large companies who expectedly follow strict guidelines with respect to the feeding of the fish, age at harvest, and other such sundry matters. The consumer may well be guided by the findings of this study in choosing which species to consume.
| Conclusion|| |
The fatty acid saturation profiles and lipid contents of six fish species [Scomberomorus maculatus (Mitchill, 1815), Micropogonias undulatus (Linnaeus 1766), Chrysichthys nigrodigitatus (Lacépède: 1803), Trichiurus japonicus (Temminck and Schlegel, 1844), Sardinella pilchardus (Walbaum, 1792), and Prochilodus lineatus (Valenciennes, 1836)] popularly consumed in Umuahia, Nigeria, were studied. The results show that S. maculatus and T. japonicus had the least lipid content, yet the most PUFA content and thus may be the most nutri-medically desirable fishes of all the studied species. Variations in environmental factors, size, age and diets of the fishes, all of which can affect the fatty acids in fish, and which could not be controlled in this study, however warrant a cautious interpretation of these results.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]