不同贮藏温度对酸乳中乳酸菌活菌数以及品质影响的研究

Effect of different storage temperatures on lactic acid bacterial count and yogurt quality

目的：探究不同贮藏温度对酸乳中乳酸菌活菌数以及酸乳品质的影响。方法：每2天分别测定于常温、4、-10、-20℃条件下贮藏酸乳的乳酸菌的菌落总数、滴定酸度、p H、持水力、质构以及感官。结果：常温条件下贮藏的酸乳在5~7 d内乳酸菌菌落总数、滴定酸度、质构以及感官评分均有提升,随后菌落总数、滴定酸度、持水力、质构以及感官评分均迅速下降;4℃条件下贮藏的酸乳在17 d内乳酸菌总数、滴定酸度、质构以及感官评分均呈上升趋势,持水力变化不大;-10、-20℃条件下贮藏的酸乳各项指标均呈下降趋势。结论：酸乳在4℃条件下贮藏时,乳酸菌生长情况以及酸乳品质最佳,可有效延长酸乳货架期。

Objectives： To validate the effects of different storage temperatures on the number of viable lactic acid bacteria in yogurt and affecting its quality. Methods： Bacterial colonies from yogurt were measured for two days at a variable temperatures-20,-10, 4 ℃ and room temperature. Conditions such as, p H, water holding capacity, texture were also measured. Results： Under normal storage conditions of yogurt after 5~7 d, the total number of lactic acid bacterial colonies and other condition titratable acidity, texture and water holding capacity were found to be improved. A decrease in temperature below 4 ℃ bacterial colonies and other condition p H, water retention, texture were affected. Storage condition at 4 ℃ after 17 d total the bacterial count and yougurt texture, water retention, p H showed an upward trend. However at temperature below 0 ℃ there occur a rapid reduction in bacterial count, water retention, p H and texture of yogurt. Conclusion： This study show that the optimum temperature for lactic acid bacteria in yogurt was 4 ℃, giving best quality of yogurt and effectively extending the shelf life of yogurt.