Changes on biogenic, volatile amines and microbial quality of the blue swimmer crab (Portunus pelagicus) muscle during storage.

Biogenic amines (BAs) are a group of substances with low molecular weight organic compounds such as aliphatic, aromatic or heterocyclic structures that are naturally present in animal tissues. The aim of this study was to investigate the changes on the formation of biogenic amine, bacterial load and biochemical characteristics in blue swimmer crab (Portunus pelagicus) at different storage temperatures (4 and 20 °C) up to 96 h. From seven BAs only four biogenic amines (tryptamine, putrescine, histamine, and tyramine) were detected while, the cadaverine, spermidine and spermine were absent in all investigated samples. Histamine was the major biogenic amine formed during the storage times and reached the highest concentration of 7.55 ± 0.46 mg/100 g and 17.68 ± 1.30 mg/100 g after 96 h at 4 and 20 °C, respectively. This level of histamine exceeded the maximum tolerance level of 5 mg/100 g. However, the proper icing procedure retarded the histamine effects, resulting only 7.55 mg/100 g after 96 h of ice storage. Spoilage indicator putrescine was only detected after 24-96 h of storage at 4 and 20 °C, respectively. The total volatile base nitrogen and the trimethylamine-nitrogen concentrations were considered to be reliable indicators of freshness index in blue swimmer crab. An aerobic mesophilic plate count of 6.68 and 7.31 log CFU/g were noted for crab stored in ice and ambient temperature after 96 h storage, respectively. It could be concluded that the biogenic amine forming bacteria and other susceptible perishing factors responsible for the biogenic amine formation could be prevented by continuous storage of P. pelagicus at low temperature.