关键词: 巴氏杀菌乳, 储存温度, 储存时间, 微生物, 理化特性

Abstract: [Objective] To study the effects of different storage conditions on the microbial and physicochemical properties of pasteurized milk.[Method] Pasteurized milk was stored at 2,7,10,15,25 and 35 ℃for 0~72 h respectively,and the changes in microbial count,pH value and acidity were measured regularly.[Result] With the extension of storage time and the increase of temperature,the total bacterial count,the number of lactic acid bacteria,and the number of coliform bacteria in pasteurized milk all increased significantly（P<0.05）.In pasteurized milk stored at 7 ℃,the microbial growth was slow,and the total bacterial count remained within the safe range at 72 h;when stored at 15 ℃,the microbial growth rate accelerated,and the total bacterial count exceeded the national standard limit after 36 h;when stored at 25 ℃ and 35 ℃,the microorganisms proliferated rapidly,far exceeding the national standard limit. The pH value of pasteurized milk gradually decreased with the extension of storage time and the increase of temperature,while the acidity gradually increased. The changing trends of both were closely related to the growth of microorganisms.[Conclusion] Refrigeration at 7 ℃ could effectively inhibit the growth of microorganisms in pasteurized milk and extend its shelf-life. When storing pasteurized milk at room temperature,it should be consumed as soon as possible to avoid quality deterioration caused by excessive microbial growth.

Key words: pasteurized milk, storage temperature, storage time, microorganism, physicochemical property