Abstract:

To enhance the product quality of Beijing traditional food “Douzhi”, the microbiological, chemical and biochemical changes during its processing were studied. Lactic acid producing bacteria were confirmed accounting for the natural acidification of mung bean milk during sedimentation. The main fermenting bacteria came from two species: Lactococcus lactis and Leuconostoc citreum, which accounted for 72% and 26% of the total, respectively. Soaking brought little change in starch content, but caused a significant reduction in crude protein and sugars and an increased level in soluble proteins and free amino acids content. This suggests that a high metabolic activity is induced during steeping. Fermentation caused a rapid reduction in soluble proteins, soluble sugars and reducing sugars and a significant accumulation in free amino acids. Mung bean endogenous protease and amylase activity dropped significantly during fermentation, while the activity of microbial protease enhanced during the latter part.

Key words: mung bean, Lactococcus lactis, Leuconostoc citreum