Investigation on the safety of Lactobacillus amylolyticus L6 and its fermentation properties of tofu whey

The objective of this study was to screen a safe strain to prepare fermented tofu whey (FTW). Lactobacillus amylolyticus L6 was isolated from spontaneously acidified tofu whey and then identified by 16S rRNA and 23S rRNA gene sequencing. Its susceptibility to antibiotics, toxic metabolites were tested and it met the requirements established by European Food Safety Authority. L. amylolytics L6 was then applied to prepare FTW. After 48 h fermentation at 42 °C, L. amylolytics L6 produced large amount of organic acid with the titratable acidity of 110 oT by utilizing sucrose, raffinose and stachyose and the pH of FTW decreased to pH 3.1. L. amylolytics L6 also converted isoflavones glycoside into aglyconde partly and resulted in the significantly (p < 0.05) increase of antioxidant activities. L. amylolyticus L6 is safe and can be potentially used as a starter culture to produce tofu coagulant and functional beverage, which could add value to the soy processing byproduct.