ANALYSIS OF BIOCHEMICAL COMPOSITION AND EVALUATION OF NUTRITIVE QUALITY IN MUSCLES OF <I>SILURUS LANZHOUENSIS</I>

Abstract

Measurements were made on biochemical components in muscles of Silurus lanzhouensis which is an endemic fish living in the middle-up reach of the Yellow River.Samples were collected from Hukou to Sanmenxia section of the Yellow River in China during 2004—2005.Main nutrient contents,amino acids,fatty acids and main mineral element were analyzed by using 6 groups and trace element by 11 groups,which from 42 individuals.Each group was composed of 3 individuals.The results showed that contents of crude protein,crude fat,ash and moisture of fresh muscle were(17.4±0.7)%,(2.22±1.09)%,(1.12±0.09)% and(80.4±0.8)% respectively.The composition of amino acids of muscle was 18,among which there were 8 essential amino acids for human needs.In dry sample,the total content of amino acids was(71.29±3.71)%;the content of essential amino acids was(30.24±2.18)%;4 kinds of delicious amino acids accounted for 24.62%.Glu was the most abundant and Cys was the shortest in all amino acids of the muscle.The percentage of essential amino acids in total was 42.38%.The essential amino acids index(EAAI) was 69.30 and the constitutional rate of essential amino acids accorded with FAO/WHO standard.According to nutrition evaluation,in the amino acids score(AAS) and chemical score(CS),the limited amino acids of Silurus lanzhouensis were Val,Leu and Ile.4 saturated fatty acids and 9 unsaturated fatty acids were found in muscle and the amount of unsaturated fatty acids was 65.210%.C18∶1 and C18∶2 were the main unsaturated fatty acids,which was 41.531% and 7.309% respectively.Minerals such as P,Na,K,Ca,Mg,Zn,Fe and Se were rich in these samples.The content of P was significantly higher than other mineral elements(p0.05).In all elements,Zn was the richest microelement,which was 10.18 mg/kg(fresh),Fe and Se were secondary and tertiary microelment,respectively,which was 8.31 mg/kg and 0.31 mg/kg.Furthermore,the ratio of Zn and Cu was not rational,so were Zn and Fe.Our study indicated that Silurus lanzhouensis was one of the freshwater fishes with better nutritive value and raising value.