Biogenic amine reduction by vasoactive amine-degrading Bacillus licheniformis CH7P22 in Enterococcus faecium-contaminated Cheonggukjang, Korean fermented soybean paste

Biogenic amine reduction by food additives in Cheonggukjang, a Korean fermented soybean paste, fermented with tyramine-producing heterogeneous bacterial species

“…The content in the B sample showed no change over fermentation period (certainly due to the absence of inoculation of tyramine-producing strains), while that in the C sample increased significantly and steadily to 148.17 ± 7.01 mg/kg until fermentation ends, exceeding the toxicity limit for tyramine (100 mg/kg) suggested by Ten Brink et al [ 12 ]. The high level of tyramine in the C sample was likely associated with the tyramine production of B. subtilis and E. faecium strains, which is in consistent with the observations from previous studies [ 15 , 23 , 25 ]. It is well-known that naturally fermented Cheonggukjang products contain these tyramine-producing bacteria [ 4 , 15 , 23 ].…”

“…As shown in Table 1 , Table 2 , LA exhibited a moderate growth inhibitory effect ( p < 0.05) on B. subtilis and E. faecium strains at concentrations of at least 1.0% and 5.0%, respectively. However, B. licheniformis CH7P22, which was deemed suitable as a BA-degrading starter and/or protective culture in a previous study [ 25 ], was unable to grow at even the lowest concentration (0.5%) of LA tested. Bacillus spp.…”

“…Food additives tested to inhibit toxic vasoactive BA (i.e., tyramine) production by prolific tyramine-producing Bacillus and Enterococcus strains which had been reported in previous studies [ 15 , 25 ] were selected based on no or less effect on Cheonggukjang flavor among those listed in both the Codex Alimentarius regional standard for fermented soybean paste in Asia [ 27 ] and the Food Additives Code of South Korea [ 28 ]. The selected food additives were TA, SP, LA, PS, and SB, and their inhibitory effects were determined through in-vitro experiments.…”

“…The Bacillus type strains, B. licheniformis KCTC 1918 and B. subtilis KCTC 3135, obtained from the Korea Collection for Type Cultures (KCTC; Daejeon, South Korea) and the BA-degrading B. licheniformis CH7P22 originated from Cheonggukjang [ 25 ] served as negative controls since they have incapacity to produce BAs. B. subtilis CB 9-4 strain capable of producing tyramine [ 15 ] was used for the determination of controlling effects of additives on tyramine production in this study.…”

“…As such, the high BA content in Cheonggukjang seems to be an inevitable risk. In previous studies, strategies applied to reduce such a high BA content in Cheonggukjang mainly include the use of starter cultures [ [24] , [25] , [26] ]. However, studies comparing the controlling effects of all applicable food additives on the formation of BAs by diverse bacterial species in Cheonggukjang are lacking.…”