Formation and destruction of biogenic amines in Chunjang (a black soybean paste) and Jajang (a black soybean sauce)

Chunjang and Jajang samples were analysed for biogenic amine contents by using HPLC equipped with a UV–Vis detector. Chunjang samples contained relatively large amounts of histamine (up to 273 mg/kg) and tyramine (up to 131 mg/kg), whereas Jajang samples had relatively small amounts of biogenic amines (mostly less than 40 mg/kg). There appeared to be a strong relationship between biogenic amine contents in Chunjang and Jajang, and the biogenic amines in Chunjang were found to be pyrolysed during frying thereof to prepare Jajang. Meanwhile, the total plate counts of Chunjang samples ranged from 5 to 8 log cfu/g, and most strains that were isolated from Chunjang samples were identified to be Bacillus subtilis (91.0%). The strains isolated from a sample in which relatively small amounts of biogenic amines were detected showed significantly weak abilities to produce biogenic amines. This indicates that biogenic amine contents in Chunjang are primarily attributed to bacterial abilities to produce biogenic amines.