Biogenic amine formation and bacterial contribution in Natto products

Abstract

Twenty-one Natto products currently distributed in Korea were analysed for biogenic amine contents and tested to determine physicochemical and bacterial contributions to biogenic amine formation. Among them, nine products (about 43%) had beta-phenylethylamine or tyramine contents greater than the toxic dose (30 mg/kg and 100 mg/kg, respectively) of each amine, although no products showed total amounts of biogenic amines above the harmful level (1000 mg/kg), which indicates that the amounts of biogenic amines in some Natto products are not within the safe level for human health. From four different Natto products, that contained noticeable levels of beta-phenylethylamine and tyramine, 80 bacterial strains were isolated. All the strains were identified to be Bacillus subtilis and highly capable of producing beta-phenylethylamine and tyramine. Therefore, it seems likely that the remarkable contents of beta-phenylethylamine and tyramine in Natto predominantly resulted from the strains highly capable of producing those amines present in the food. (C) 2012 Elsevier Ltd. All rights reserved.