The potentials of Bacillus licheniformis strains for inhibition of B. cereus growth and reduction of biogenic amines in cheonggukjang (Korean fermented unsalted soybean paste)

- The selected Bacillus licheniformis strains were used for cheonggukjang fermentation.
- The strains produced the low level of biogenic amines in cheonggukjang.
- The strains have the ability to inhibit B. cereus growth in cheonggukjang.
- The cheonggukjang samples fermented by the strains had the acceptable qualities.
- The strains were effective for reduction of B. cereus and biogenic amines.

The aim of this study was to control Bacillus cereus growth and biogenic amines formation by using a starter in cheonggukjang fermentation. We used the four selected B. licheniformis strains for cheonggukjang fermentation and investigated whether the strains are effective in reducing both B. cereus level and biogenic amines content. We confirmed that the selected strains are able to reduce B. cereus level to below l log CFU/g after cheonggukjang fermentation from the initial level of 3-4 log CFU/g (artificial contamination). Tryptamine, β-phenylethylamine, putrescine, cadaverine, tyramine, spermidine, and spermine were detected whereas histamine, serotonin, noradrenaline, and dopamine were not detected in the cheonggukjang samples. Most of biogenic amines contents were lower than those of previous studies, indicating that the strains produced the low level of biogenic amines in cheonggukjang fermentation. The acceptable levels of amino-type nitrogen, free amino acids, and isoflavones were contained in the cheonggukjang samples. These results demonstrate that the selected strains are not only effective for reduction of both B. cereus contamination and biogenic amines but also suitable for preparation of cheonggukjang with good quality.