Fixed-bed degradation of histamine in fish sauce by immobilized whole cells of Natrinema gari BCC 24369

Abstract

Fish sauce often contains histamine at high levels, which may cause its rejection for export and is also associated with the food poisoning. Therefore, this study aimed to apply the ability of immobilized whole cells of Natrinema gari BCC 24369 to degrade histamine in fish sauce. Under static condition, the optimum conditions for histamine degradation in fish sauce were using 10 % immobilized cells of Nnm. gari BCC 24369 for fish sauce (pH 6.5) in the presence of 10 mg/100 ml of riboflavin for 2 h, in which the immobilized cells exhibited a maximum histamine removal efficiency of 24 ± 1 %. The operation of immobilized cells in a fixed-bed bioreactor was more efficient than static batch operation for histamine removal. At the optimal feeding flow rate of 0.5 ml/min, a significant amount of histamine in fish sauce (51 ± 3 %) was removed as the result of histamine-degrading activity of the cells. After treatment with immobilized cells, not only was histamine effectively removed, but color darkening was also reduced. Additionally, no detrimental effects on the unique quality of fish sauce were observed during 6 months of storage.