Differences in compositions of free amino acids, nucleotide-related compounds, and fatty acids between sexes of the coconut crab Birgus latro in Okinawa, Southwest Japan

Abstract

Despite the dietary utilization of the coconut crab Birgus latro throughout history, little is known about its nutritional composition and quality. This study assessed the differences between male and female coconut crabs caught in Okinawa, southwest Japan, in meat yield and compositions of free amino acids (FAA), nucleotide-related compounds (NRC), and fatty acids in muscle and hepatopancreas. The ratios of edible muscle and hepatopancreas to whole body weight were similar in males and females. Although concentrations of histidine and tryptophan in muscle and AMP in hepatopancreas differed in males and females, these differences were small, as were taste activities and equivalent umami concentrations, suggesting that the tastes of these tissues in males and females would be nearly identical. Fatty acid composition in muscle differed lightly between the sexes, with amounts of the 20:5n-3 and 22:6n-3 being significantly greater in males. However, the ratio of n-3 to n-6 polyunsaturated fatty acids and atherogenic and thrombogenic indices suggested that all lipids from both males and females are healthy for humans. There were no noticeable differences between the sexes in meat yield; FAA, NRC and fatty acid compositions; or nutritional qualities.