Quality assessment of fermented soybeans: physicochemical, bioactive compounds and biogenic amines

In this research, a total of 47 samples from five types of fermented soybeans were selected. The physicochemical parameters, biogenic amines (BAs) and bioactive compounds such as isoflavones, total phenolic (TPC) and γ-aminobutyric acid (GABA) were investigated. The results showed that the contents of isoflavones ranged from 598.06 mg/kg to 2725.03 mg/kg in all samples and it varied from 598.96 mg/kg to 2241.67 mg/kg in Semen Sojae Preparatum (SSP) which was higher than other types of fermented soybeans. The maximum variation of GABA content was found in Aspergillus-type douchi (AD) samples. The maximum value of TPC in SSP was 4.53 g/kg. For BAs, the indicator of spoilage, 4.26% of fermented soybeans samples may lead to histamine poisoning and 42.55% of samples with total BAs contents exceeding 100 mg/kg may be harmful to human body. It indicated that different types of fermented soybeans had various bioactive compounds and BAs, so different fermented soybeans could be selected according to bioactive substances. This finding could provide comprehensive information of health beneficial compounds and BAs risks of fermented soybeans. It could guide consumers to select healthy, nutritious and safety fermented soybeans.