Bacteria-enzyme synergistic starter for preparing yoghourt

The invention discloses a bacteria-enzyme synergistic starter for preparing yoghourt. The bacteria-enzyme synergistic starter comprises skimmed milk, compound lactic acid bacteria and a compound enzyme preparation, and the compound lactic acid bacteria are composed of lactobacillus delbrueckii subsp. Bulgaricus LSR-L-L1, lactobacillus delbrueckii subsp. Bulgaricus LSR-L-L2, streptococcus thermophilus LSR-Q-G1 and streptococcus thermophilus LSR-Q-G2. The compound enzyme preparation is composed of neutral protease and lactase. The preparation method of the leavening agent comprises the followingprocess steps of (1) blending raw milk; (2) preparing compound lactic acid bacteria; (3) adding a compound enzyme preparation; and (4) adding compound lactic acid bacteria into the raw milk, fermenting for 4-6 hours at the temperature of 40-42 DEG C, stopping fermenting when the titration acidity reaches 90-100 DEG T, and refrigerating at the temperature of 4-6 DEG C to obtain the yoghourt starter. The method has the ben