市售酸奶保存期内乳酸菌数的动态研究
关键词：酸奶；乳酸菌数量；平板计数法3847
Dynamic Study on Lactic Acid Bacteria Number of Yogurt on the Market in Shelf Life
Abstract: In this experiment, we used yili yoghurt (natural) as the esearch object, respectively counted the number of three samples of lactic acid bacteria (one sample was at temperature 4℃,one was 37℃ and one was 25℃,which was room .)by the plate count method.One yogurt sample stored under 4℃ was placed under the normal temperature for 5 hours, the number dynamic change of lactic acid bacteria in the process was reckoned. (GB19302-2010) by comparing the national standard of check qualified yogurt yogurt quality standards. results show that 4℃ is the most suitable temperature to store yogurt, during the warranty period, the number of lactic acid bacteria in line with the national food safety standards; the time is the shortest Under the condition of 37℃, the number of lactic acid bacteria have not meet the national food safety standards from the sixth day; Yogurt can be saved eight days under normal temperature without metamorphism, yogurt buying process will not have big effect on the quality of the yogurt.
Key words: Yogurt; Lactic acid bacteria number; Plate count method
目 录
摘 要 1
Abstract 1
引言 2
1. 材料与方法 2
1.1 试验样品 2
1.2 主要试剂与仪器 2
1.2.1 试剂 2
1.2.2 主要仪器 3
1.3 培养基 3
1.3.1 培养基主要成分 3
1.3.2 培养基的的配制及其灭菌 3
1.4 实验方法 3
2. 实验过程 3
2.1 准备 3
2.2 样品稀释 4
2.3 平板制作及菌落培养 4
2.4 菌落计数 4
2.5 实验重复 4
3. 结果 5
3.1 菌落观察结果 5
3.2 菌落计数结果 5
3.2.1 在4℃条件下储存的酸奶中乳酸菌数的动态变化 5
3.2.2 在常温条件下储存的酸奶中乳酸菌数的动态变化 6
3.2.3 在37℃条件下储存的酸奶中乳酸菌数的动态变化 7
3.2.4 储存酸奶购买过程中乳酸菌数量动态变化 8
3.2.5 不同温度下酸奶中乳酸菌数量变化对比 9
4. 分析与讨论 9
参考文献 10
致谢 12,3847
市售酸奶保存期内乳酸菌数的动态研究
引言
酸奶中含有大量的活性乳酸菌，可定居在人体鼻粘膜或消化道等处，乳酸菌代谢产生的乳酸能降低肠道内的pH值，抑制肠道中腐败菌的生长，减弱腐败菌的产毒作用，从而文持体内微循环环境。但乳酸菌活菌体的数量需达到一定程度才有可能使乳酸菌定植在人体的肠道内，文护人体健康[1]。对市售酸奶保存期内乳酸菌数的动态研究对于了解市场上所售酸奶质量是否合格，饮用对人体是否有益具有重要意义。