Studies on the biochemical composition, energetics and essential amino acids of three mudskippers in Xiamen Harbour

Abstract

Measurements were made on the contents of protein, lipid, glycogen (PLG) and water, and on caloric values and amino acids, in muscle of three mudskippersPeriophthalmus cantonensis, Scarteiaos viridis andBoleophthalmus pectinirostris collected from Haicang, Xiamen. The essential amino acids (EAA) for these fishes were also studied with radioisotopic trace method. The results showed: (1) The content of each component in tested fish muscles differed slightly, and protein was the most important component making up from 6.685% to 9.891% of the wet weight (about 44.21%–50.45% of dry weight); (2) Energy calculated from the sum of protein, lipid and glycogen in wet muscle was low (<4.3kJ/g) in these fishes, especially inB. pectinirostris (<3.1 kJ/g); the ratios of energy to protein content (E/P) also were low (<39.873–45.535kJ/g); (3) Seventeen amino acids were determined in these three fishes. The content of the same amino acid (among the seventeen) tested in different species and sexes varied slightly. The amounts of methionine, phenylalanine lysine, arginine, histidine, threonine isoleucine and leucine which are indispensable for the needs of human beings and animals were relatively high, accounting for 47.35%–48.06% of the total amino acid content. (4) Leucine, isoleucine, arginine, lysine, phenylalanine, tryptophan, methionine, histidine, threonine, and valine, are essential in the diet of the three mudskippers as the radioisotopic trace method using D−[U−14C]-glucose showed little or no radioactivity was incorporated into these ten amino acids.