青贮饲料用乳酸菌发酵剂冻干保护剂的筛选

Selection of freeze drying protective agent of lactic acid bacteria starter for silage

为了提高青贮饲料用直投式乳酸菌发酵剂的生物活性,采用单因素试验和正交实验比较多种冻干保护剂组合对菌体细胞的保护效果。结果表明,添加各单一冻干保护剂和正交实验的9种复合冻干保护剂均能显著提高冻干后乳酸菌菌体细胞的存活率（P〈0.05）,并且对乳酸菌菌体细胞的保护效果均优于各单一冻干保护剂,其中添加各单一冻干保护剂的乳酸菌在冻干后细胞的存活率在30.25%~70.43%之间,而添加正交实验中9种复合冻干保护剂的乳酸菌菌体细胞的冻干存活率在71.45%~92.18%之间。最佳的冻干保护剂配方为脱脂奶粉100 g/L,海藻糖40 g/L,三聚磷酸钾20 g/L,抗坏血酸30 g/L,（均为质量浓度）;验证实验表明,冻干后的发酵剂中菌体细胞的存活率为95.47%。

In order to improve the biological activity of lactic acid bacteria DVS starter culture for silage. Single factor test and orthogonal test was applied to compare the protective effect on bacterial cell of a variety of combinations of cryoprotectants during freeze drying. Results show that the survival rates of lactic acid bacteria cell after freeze drying are significantly improved by each single and nine kinds of combinations of cryoprotectants used in orthogonal test （P〈0.05）. And the protective effects of the nine kinds of combinations of cryoprotectants are all bet- ter than that of every single cryoprotectant. Moreover, the survival rate of lactic acid bacteria cells after freeze drying added with each single cryoprotectant is between 30.25% and 70.43%, while that of cells added with the nine kinds of combinations of cryoprotectants is between 71.45% and 92.18%. The best formula of the combination of cryoprotectants contained 100 g/L skim milk, 40 g/L trehalose, 20 g/L potassi- um triphosphate and 30 g/L% ascorbic acid, and verification test shows that the survival rate of the cells in starter culture after freeze drying was 95.47%.