Nutritional Composition of Muscles from 8 Species of Economic Fishes

Abstract

The biochemical composition,including fatty acids and amino acids profiles in the muscles of eight species of fish available on the market in China was examined.The eight species studied included fish farmed in freshwater(Cyprinus carpio,Ophiocephalus argus,Aristichthys nobilis),fish farmed in seawater(Lateolabrax japonicus,Cynoglossus semilaevis),and wild fish from the Yellow Sea(Pseudosciaena crocea,Trichiurus haumela,Stromateoides argenteus).Data suggested that the lowest protein content on a wet weigh basis was observed in the muscle of O.argus(16.21%) farmed in freshwater,while the highest was marine fish: L.japonicas(21.31%) and T.haumela(20.83%).Three species of marine wild fish were found to have abundant lipids in their muscles.The highest lipid content was found in T.haumela(7.90%) and P.crocea(5.10%) caught in the Yellow Sea,while the lowest was noted in the muscles of C.semilaevis(0.92%) farmed in seawater.The percentage of polyunsaturated fatty acids(PUFAs) in freshwater fishes was also found to be higher than in marine fish in the current study,but the ratio of n-3 to n-6 in marine fish(7.47—1.60) substantially exceeded that found in freshwater fish(0.09—2.20).The main PUFAs from all fish species tested were docosahexaenoic(DHA) and eicosapentaenoic(EPA),and the percentage of DHA in the lipids was higher than that of EPA.The lowest DHA/EPA ratio was noted in C.carpio(2.65) from freshwater.A relatively higher DHA/EPA ratio was currently observed in the lipids of P.crocea(23.05),O.argus(23.02),and L.japonicas(22.49).Three freshwater fishes were rich in linoleic acid(LA,C 18:2 n 6c).The contents of n-3 PUFAs and(EPA+DHA) in the muscle of C.carpio were found to be lowest.The lowest total amino acid(TAA) content on dry weight basis was noted in the muscles of T.haumela(62.74%),and the highest was found in C.semilaevis(77.36%).C.semilaevi also had the highest content of essential amino acids(EAA)(32.09%) while S.argenteus had the lowest EAA content(26.20%).The TAA and EAA contents of reared fish,including freshwater fish and marine fish,were both higher than those of the marine wild fish tested.The predominant amino acids among the essential amino acids of all fish species tested were threonine,leucine,and lysine while the nonessential amino acids were glutamic acid and aspartic acid.Farmed marine fish were found to be richer in amino acids than fish farmed in freshwater and wild marine fish in the current experiment.When compared with the FAO/WHO reference pattern established for pre-school children(2—5 years old),all the amino acid scores exceeded 100 with the exception of phenylalanine and tyrosine,leucine for A.nobilis,and isoleucine for C.semilaevis.Thus,the protein in the eight fish species available on the Chinese market was well-balanced in terms of essential amino acids.In this study,L.japonicas from seawater showed better nutritional quality than other fish.Three marine wild fish species(P.crocea,T.haumela,and S.argenteus) were more abundant in n-3 PUFAs,and had high levels of lipids.