Changes in biogenic amines and microbial loads in the muscle of orange-spotted grouper, Epinephelus coioides (Hamilton, 1822) during ice storage

The composition of selected biogenic amines, pH, psychrophilic and mesophilic bacterial loads in orange-spotted grouper kept in ice were investigated for 18 days. Fish weighing 800.15 +/- 196.85 g were purchased immediately following capture with no eviscerating. In each experimental time, three random fish were withdrawn and each biogenic amine, including histamine, putrescine, cadaverine and tyramine were determined in triplicate using HPLC technique. Although the obtained data showed significant increasing trends (p < 0.05) for all measured amines, the cadaverine was not detected significantly. In addition, there were no detectable biogenic amines initially. However, the highest value for histamine was attributed to 70.37 mu g. g(-1) of fish muscle obtained at 12th days of storage. The initial (day 0) concentrations were 3.22 and 2.96 mu g. g(-1) and the maximum levels were obtained 19.87 and 14.37 mu g.g(-1) for putrescine and tyramine respectively. Biogenic amine index also rises from 0.15 up to 62.57 during 18 days of ice storage. The increases in pH, psychrophilic and mesophilic bacteria loads were significant (p < 0.05) as storage time progressed. In this respect, psychrophilic bacteria were considered as dominant microorganism during ice storage of orange-spotted grouper. The best correlation was also observed between tyramine and mesophilic bacteria (r = 0.977, p < 0.001). Although the amounts of biogenic amines were increased during this study, these levels were not exceeded than that of reported as allowable level for human consumption. The results suggest that the control of storage conditions and bacterial presence might play an important role to hider the formation of biogenic amines in fish meat.