Abstract:
Biogenic amines (BAs) are of great concern as endogenous contaminants. Appropriate levels of BAs are beneficial to human health ; however, high levels of BA intake can cause toxic reactions, and even pose a threat to human health. Moreover, excessive levels of histamine (HM) and tyramine (TYM), two of the most toxic BAs, in the diet may result in allergic reactions. This study is aimed detecting the contents of BAs in fermented soybean products, isolating key strains capable of producing BAs, and developing effective phytochemicals for the reduction of BAs.The level of BA and its formation in fermented soybean foods were analyzed. The results indicated that phenylethylamine (PHM), HM, TYM and putrescine (PUT) were the dominant BAs in soy sauce products, and the total BA levels ranged from 6.46 mg/L to 317.49 mg/L. TYM was the predominant BA in thua nao, accounting for over half of the total BAs. The average total BAs content in dried thua nao was 342 mg/kg, which exceeded that in fresh thua nao (239 mg/kg). The calculated maximum estimated daily intake (EDI) and index of food safety (IFS) of TYM were 1.51 μg/kg/day and 0.008, respectively, among the age groups consuming thua nao, indicating a low risk to human health. Nevertheless, the acute risk index of TYM in fresh thua nao and dried thua nao among patients taking monoamine oxidase inhibitors (MAOIs) was greater than 80 %. Consequently, these results indicated that an adverse health effect is improbable for the general population after excessive consumption of TYM-contaminated thua nao ; however, it may have significant health implications for patients taking MAOIs. We discovered a good linear relationship between the HM and TYM contents in soy sauce products, and TYM showed a significant positive correlation with the total BAs in thua nao. Subsequently, the Bacillus tropicus-HT-31-2 and Millerozyma farinosa-HT-42-1 isolated from moromi, the fermented stage of soy sauce, demonstrated high levels of HM (43.62±3.46 mg/kg, 26.52±2.42 mg/kg) and TYM (26.03±3.13 mg/kg, 11.15±1.35 mg/kg) in the simulation medium, respectively. Meanwhile, Proteus mirabilis-T-24-2 from thua nao displayed a remarkable capacity for accumulating TYM, with levels reaching as high as 159.55±6.56 mg/kg in the simulation medium. Finally, the inhibition effects of seven phytochemicals on BAs formation were examined. Quercetin presented a good result in BAs inhibition, and the contents of PUT and HM decreased by 37.72% and 34.34%, respectively.The objective of this study is to provide a theoretical foundation for the control of BA level in soy sauce and thua nao. Moreover, this approach might enhance the comprehension of the research community and contribute to the progress of fermented soybean foods.