影响原料乳品质的纤溶酶活性的因素分析  

Analysis on factors affecting plasmin activity of raw milk quality

作　　者：张书文[1] 刘鹭[1] 孙洁[2] 李红娟[1] 崔文明[1] 芦晶[1] 吕加平[1] 

机构地区：[1]中国农业科学院农产品加工研究所,北京100193 [2]农业部规划设计研究院,北京100125

出　　处：《农业工程学报》2014年第13期286-292,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(31301521;31371808);现代农业产业技术体系北京市奶牛产业创新团队;国家科技支撑计划(2012BAD29B03;2013BAD18B10)

摘　　要：为了充分了解原料乳中纤溶酶活性,以便从源头上提高原料乳品质,该文针对中国原料乳的生产现状,分析了奶牛品种、胎次、养殖模式及挤奶时间对原料乳中纤溶酶活性的影响,并对纤溶酶的热稳定性进行了研究。结果表明,养殖模式、奶牛品种及胎次对原料乳中纤溶酶活性影响显著(P<0.05),牧场养殖、1、4胎和娟珊牛原料乳中纤溶酶活性显著低于养殖小区、2、3胎及荷斯坦牛乳中的纤溶酶活性;挤奶时间对原料乳中纤溶酶活性影响不显著(P>0.05);原料乳中纤溶酶活性随热处理温度的升高而逐渐下降,巴氏杀菌(75℃、15 s)仅可使原料乳中纤溶酶活性下降25%;半胱氨酸对乳中纤溶酶活性具有一定的抑制作用。研究结果对根据纤溶酶活性对原料乳进行品质评价及分级具有一定借鉴作用。Plasmin（PL） is by far the predominant and most completely studied endogenous protease in bovine milk. PL activity level is an important factor affecting dairy product quality and its processing characteristics. Raw milk with a high PL level can have detrimental effects on the quality of pasteurized milk and UHT milk, causing undesirable flavor, precipitation and gelation, and shortening the shelf life of the product. Considerable research has focused on minimizing the activity of PL in fluid milk. Many factors, such as pH, mineral content, whey proteins, and storage temperature can influence the kinetics of the PL-induced hydrolysis. However, according to China＇s current raw milk production situatioin, the objective of this study is to determine how such factors such as cattle breed, parity, dairy farming mode, and milking time affect PL activity in milk; thermal stability of plasmin is also studied. The results show that the PL activity between dairy farming mode, parity, and cow breeds are significant（P〈0.05）. Although there are effects of dairy farming mode, parity, and cow breeds on plasmin activity, they are lower in large scale farming, parity（1,4）, and Jersey cows. However, the effect of the milking time on PL activity is not significant（P〉0.05）. PL activity of raw milk gradually decreases with increasing thermal treatment temperature. However, the thermal treatment associated with pasteurization of milk（75℃, 15 sec） has been shown to increase PL levels. This increase in PL activity has long been attributed to inactivation of plasmin inhibitors（PI） and plasminogen activator inhibitors（PAI）, but plasminogen activators（PA）is even more heat stable than PIand PAIduring pasteurization and UHT. In this temperature range, plasminogen（PG） loses its naturally occurring tertiary structure, but is not yet inhibited. On the contrary, PG becomes more accessible to the action of PA by unfolding of its kringles. Activation of PG is enhanced upon pasteurization heating. Further

关 键 词：酶 品质控制 热处理 原料乳 纤溶酶 影响因素 热稳定性 

分 类 号：TS252.2[轻工技术与工程—农产品加工及贮藏工程]