直投式酸奶发酵剂的商品化生产研究

Commercial production of DVS yogurt starter cultures.

通过对不同保加利亚乳杆菌与嗜热链球菌菌株的酸化活力、黏度、蛋白水解能力和共生能力等生理学指标的测定,筛选出4对适于发酵生产用的菌株组合,并以菌株Y6+ST1作为进一步研究对象,获得其最佳增殖培养基为番茄汁为2.5%,乳糖为1.0%,酵母膏为0.5%,蛋白胨为1.5%,42℃培养6h后其活菌数达到1.4×109mL-1;Y6+ST1组合的最佳保护剂组成为脱脂奶粉为18.0%,甘油为2.0%,谷氨酸钠为1.0%和吐温-80为0.5%,经冷冻干燥后其活菌数达到3.62×1011g-1。该组合工业化生产的最佳工艺参数是培养温度42.3℃,pH值为6.4,搅拌转速86.8r/min和3%的接种量,1.0%补料(脱脂乳),发酵时间6h;-40℃,15h后,最终冷冻干燥产品活菌数为1011g-1。

The interactions （including the symbiosis and antagonism）, their abilities to produce lactic acid, viscosity,and amino acid between Streptococcus thermophilus strains and Lactobacillus delbrueckii subsp, bulgaricus strains were studied. It was seen that 4 paired strains were more suitable for the production of yogurt. For strains Y6-ST1, the best medium was 2.5% of tomato extract, 1.0% of lactose, 0.5% of yeast extract and 1.5% of peptone.If they were cultivated at 42℃ for 6h, The cell population was up to 1.40×10^9 mL^-1 The optimal cryoprotectants to improve the viability of strains Y6-ST1 were investigated .A combination consisting of NFMS（18%）, glycerin （2.0%）, glutamate-Na （1.0%） and Sorbitan mono-oleate （0.5%） produced a very positive effect on promoting the viability of the paired strains LB2-ST1.Their viable cells after freeze-drying were 3.62×10^11g^-1 The optimal parameters for the production of yogurt starters were： temperature 42.3 ℃,pH=6.4,rotating speed 86.8 r/min, inoculation3%,feeding 1.0%,fermentation 6 h, freeze-drying -40℃,15 h.The cell of the production were10^11g^-1.