影响原料乳中蛋白酶活性的多因素分析及相关性研究

Multi-factor analysis and correlation study on the activity of proteinase in raw milk

中文关键词:  乳制品  原料乳  蛋白酶  影响因素

英文关键词:dairy product  raw milk  protease  influencing factors

中文摘要:

      目的 探究影响原料乳中蛋白酶活性的因素。方法 以原料乳以及不同工艺处理前后奶样为样本, 基于福林酚法测定酸、碱、中性蛋白酶活性, 在牧场和工艺层面分析不同地区、季节、牧场温度、体细胞数、嗜冷菌数目及行为应激对牛奶样本蛋白酶活性的影响, 并对不同处理工艺对产品蛋白酶活性的影响进行分析。结果 牧场层面对蛋白酶活性变化的贡献率依次为: 季节(导致的温度变化)>牧场最高温度>地区>嗜冷菌数>体细胞数。在不同处理工艺对蛋白酶灭活率的对比中, 4种处理工艺对蛋白酶灭活率的大小依次为: 超高温灭菌(ultra-high temperature treated, UHT)前预热处理(90 ℃、5 s)> 巴氏杀菌前热处理(70 ℃、5 s)>反渗透(reverse osmosis, RO)膜>离心除菌。结论 在牧场层面主要影响因素为季节导致的温度变化对蛋白酶活性的影响; 在工艺层面同时采用杀菌前预热处理的方式可以使蛋白酶的灭活率达到50%以上。

英文摘要:

      Objective To explore the factors affecting protease activity in raw milk. Methods Used raw milk and milk samples before and after different processing techniques as samples, acid, alkali and neutral protease activities were determined based on the Folin phenol method. The effects of different regions, seasons, ranch temperatures, somatic cell numbers, number of psychrophilic bacteria, and behavioral stress on protease activity in milk samples were analyzed at the ranch and process levels, and the effects of different processing techniques on product protease activity were analyzed. Results The contribution rate of protease activity changes at the ranch level was in the following order: Season (resulting in temperature changes)>highest temperature on the ranch>region>number of psychrophilic bacteria>number of somatic cells. In the comparison of protease inactivation rates under different treatment processes, the 4 treatment processes had the following order of protease inactivation rate: Ultra-high temperature treated (UHT) preheating treatment (90 ℃, 5 s)>pre heat treatment before sterilization (70 ℃, 5 s)>reverse osmosis (RO)>centrifugal sterilization. Conclusion The main influencing factor at the ranch level is the seasonal temperature changes that affect protease activity, simultaneously using preheating treatment before sterilization at the process level can achieve a protease inactivation rate of over 50%.