Optimization of soymilk fermentation by the protease-producing lactobacillus paracasei

Abstract

Our aim was to ferment soymilk using lactic acid bacteria that showed protease activity and to optimize the condition for fermentation. In total, 108 strains of protease-producing lactic acid bacteria were isolated from various fermented foods such as kimchi and jeotgal, and among them, 29 strains displaying the highest protease activity were selected for further study. From these 29 strains, strain MK1, whose protease activity was 126 mU/mL·min, was selected as the optimal fermentation strain owing to its high ability to digest soymilk protein. It was henceforth labeled as Lactobacillus paracasei MK1. The optimum conditions for the fermentation of soymilk by using L. paracasei MK1 were determined to be as follows: 30 h of fermentation time at a temperature of 30°C, and at a pH of 6.0 in the initial growth medium. © The Korean Society of Food Science and Technology.