冷藏时间对牛乳品质影响的实验研究

Experimental Study on Effect of Storage Time on Quality of Milk

为研究冷藏时间对牛乳品质的影响,分别采用了标准平板培养计数法、滴定法、考马斯亮蓝G-250法、罗紫-哥特里(Rose-Gottlieb)法和比色法等生物化学分析的方法,实验测量了杯装牛乳在冷藏温度为3℃保存时,其菌落总数(total bacterial count TBC)、新鲜度及其蛋白质、脂肪、乳糖等营养成分随冷藏时间的变化规律。研究结果显示,与新鲜牛乳相比,杯装牛乳在3℃保存3天后,菌落总数和新鲜度明显变化。5天后营养成分中脂肪含量和蛋白质含量分别下降了54.5%,35.2%,而乳糖的含量变化无明显规律。

The aim of this work is to investigate effect of storage time on quality of milk. Microbial plate counts, acidity, the contents of fat, protein, and lactose of cup-packaged milk were obtained when stored at 3% in a refrigerator for five days. The biochemical means used were plate count agar, titration, Coomassie Brilliant Blue G - 150, Rose-Gottlieb, and colorimetry. In comparison with fresh milk, the TBC （total bacterial count） and the acidity of the milk stored for 3 days change obviously. After 5 days, the contents of fat and protein decrease by about 54.5% and 35.2%, respectively while the content of lactose changes irregularly.