Study On The Technology Of Producing Soy Yogurt Of High Lactobacillus Activity

Study was made on the technology of producing soy yogurt of high lactobacillus activies. Experiments were made to find out the effect of four different kinds of drying techniques on the number of living bacteria in soy yogurt powder. The results showed: Using Freeze drying method,the living bacteria in t soy yogurt powder reached 5.6×107 cfu/g,which was much more than living bacteria by the other 3 drying methods(Vacuum drying, Atmospheric drying, Low-moisture drying), which are namely3.2×106 cfu/g, 2.8×107 cfu/g, 8.9×106 cfu/g. So Freeze drying method was the best drying techniques between the four.The research was carried out to discuss the protection on lactic acid bacteria from different protectors like corn starch, nonfat milk powder, glucose, maltose, lactose, sucrose, trehalose, sodium alginates etc. The results showed: the protection of nonfat milk powder on lactic acid bacteria was significant, of which the survival rate of active cells reached 64.2%. The protection of mixed protection agent (25% nonfat milk powder+5% sucrose+5% trehalose) on lactic acid bacteria was more significant, of which the lactic acid bacteria survival rate as 89%.By the optimization selection of the basic medium for lactic acid bacteria, the best medium could be gotten: basic medium+1% soya peptone+1% soya oligofructose+0.7% yeast extract+10% tomato juice+15% turnip juice+1% maize liqued+3% beer, and when the enhancement was over, the viable count got 8.14×109cfu/mL.