原料乳体细胞数对UHT乳贮藏期间品质的影响  

Effect of Somatic Cell Count on UHT Milk's Quality during Storage

作　　者：林莹莹 任发政[1,2] 王紫薇[2] 何雨桐 郭慧媛[1,2] Lin Yingying;Ren Fazheng;Wang Ziwei;He Yutong;Guo Huiyuan(The Innovation Centre of Food Nutrition and Human Health,College of Food Science and Nutritional Engineerings China Agricultural University,Beijing 100083;Key Laboratory of Functional Dairy,Ministry of Education,China Agricultural University,Beijing 100083)

机构地区：[1]中国农业大学食品科学与营养工程学院食品营养与人类健康高精尖创新中心,北京100083 [2]教育部北京市共建功能乳品重点实验室,北京100083

出　　处：《中国食品学报》2019年第4期209-216,共8页Journal of Chinese Institute Of Food Science and Technology

基　　金：北京市科技计划课题(Z181100009318005)

摘　　要：为了探究体细胞数与蛋白质、脂肪水解的关系及其对凝胶和脂肪上浮等劣变的影响。试验采集30,80万个/mL两组不同体细胞数的原料乳,制成UHT乳,20℃下做180 d的贮藏期试验,每隔30 d测定酶活、蛋白含量、游离脂肪酸、脂肪球粒径等指标。结果显示,经UHT处理,两组产品中纤维溶酶和脂肪酶基本丧失活性,贮藏期间无显著性变化(P>0.05)。各酪蛋白组分发生显著水解(P<0.05),κ-酪蛋白和αS2-酪蛋白降幅高达90%以上,均未发生蛋白间的相互交联,体系的黏度并无显著变化(P>0.05)。脂肪球粒径在第60天迅速增加,之后无明显变化;高体细胞数组脂肪球表面的蛋白膜崩解,脂肪球聚集,从贮藏期第120天开始出现脂肪上浮;而低体细胞数组脂肪球膜蛋白也发生水解,未出现脂肪上浮。本研究表明在现有工艺条件下UHT乳出现的主要问题是脂肪上浮而非蛋白凝胶,将原料乳体细胞数控制在30万个/mL的水平,可以有效防止产品贮藏期内发生脂肪上浮,为UHT乳的品质控制提供了理论依据。In order to explore the relationship between somatic cell count and protein and fat hydrolysis, and its influence on the gelation and fat separation.Raw milk with different somatic cell count (300 000 ml, and 800 000 mL) were collected and processed into UHT milk.Samples were stored under 20℃ for 180 days and tested every 30 days for enzyme activity, protein content, free fatty acids, viscosity, fat globule size and other indicators.The study showed that after UHT sterilization, milk plasmin and lipase has been nearly completely deactivated and were constant during storage (P > 0.05).The casein components were significantly hydrolyzed (P<0.05),κ-casein and αS2-casein decreased by more than 90%, But no protein cross-linking occurred, no significant change in viscosity during storage period.Particle size of UHT milk fat globules increased rapidly in the first 60 day, no significant change later.The fat globule membrane in high somatic cell count was hydrolyzed under CLSM, the fat globules have aggregated since the reduction of protein, which causing fat separation from the 120 day after storage.No fat separation occurred in low somatic cell count though fat globule membrane hydrolyzed obviously.The results showed the main problem with UHT milk under existing process conditions is fat separation rather than the gelation, then the occurrence of fat separation could be prevented effectively by controlling the raw milk somatic cell count under 300 000/mL in the storage period, which provided the theoretical basis for the quality control of UHT milk.

关 键 词：UHT乳 体细胞 蛋白水解 脂肪水解 脂肪上浮 

分 类 号：TS252.1[轻工技术与工程—农产品加工及贮藏工程]