摘要:
以青藏高原牧区分离筛选出的低温乳酸菌为研究对象,以活菌数为指标,比较了4种冻干保护剂对复合低温乳酸菌发酵剂的影响,并通过正交实验优化了其中3种较优冻干保护剂的复配配方。结果表明,复合低温乳酸菌冻干保护剂的最优组合为:甘油为8m L/L,蔗糖为10%(w/v),脱脂乳为15%(w/v),以此为保护剂冻干存活率达到了90.55%。与商业发酵剂相比,低温发酵剂发酵酸乳组织状态良好,滴定酸度为92°T,感官评分为95分,活菌含量(10.3lg CFU/m L)极显著高于商业发酵酸乳(p<0.01)。实验结果为制备高活力直投式低温乳酸菌发酵剂的冻干菌粉提供理论支撑,对开发低温乳酸菌发酵剂具有重要意义。
Abstract:
Low temperature lactic acid bacteria,isolated from traditional fermented yak milk from qinghai-tibet plateau areas were used as the research object.The impact of four kinds of cryoprotectants on the survival rate of lactic acid bacteria complax starter during storage was assessed.Based on the results,orthogonal experiment was adopted to optimize cryoprotectant composition.The results showed that the optimum cryoprotectant composition was glycerol 8m L/L,sucrose 10%( w/v),skimmed milk 15%( w/v). The rank of protection effect on the viable counts was skimmed milk > glycerol > sucrose,and the freeze-dried survival rate was 90.55%. Compared with commercial starter culture,low temperature starter fermented yogurt had better texture,and the acidity was 92° T.The sensory evaluation value was 95 points,and the viable counts( 10.3lg CFU/m L) significantly higher than commercial starter culture fermented yogurt( p < 0.01).
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