嗜冷菌对UHT乳品质的影响研究  

Effect of Psychrophilic Bacteria on Quality of UHT Milk

作　　者：李晓建 吕阳[2] 郭慧媛[2] 

机构地区：[1]蒙牛乳业(唐山)有限责任公司,唐山064000 [2]中国农业大学食品科学与营养工程学院食品质量与安全北京实验室,北京100083

出　　处：《中国奶牛》2014年第2期30-34,共5页China Dairy Cattle

基　　金：十二五"国家科技支撑计划"项目"南方大城市奶牛健康养殖生产技术集成及产业化示范"(2012BAD12B08)

摘　　要：摘要：原料乳嗜冷菌污染是影响uHT乳保质期的重要原因之一，并且嗜冷菌分布具有地域特征性本研究对蒙牛8个牧场原料乳中的嗜冷菌进行了分离和鉴定，确定了牧场常见嗜冷菌种类及特性，并分析了其对uHT乳品质的影响．结果表明，从试验样品中分离出的嗜冷菌为假单胞菌属、微球菌属和产碱杆菌属；牧场原料乳的嗜冷菌数量与气温有关，1～3月份数量较高，6～9月份数量较低；原料乳嗜冷菌数越多，UHTqL货架期越短；原料乳中嗜冷菌数达到10^5 CFU／mL时，对uHT乳苦味值的影响显著（p〈（1．（15）；嗜冷菌脂肪酶活力达10IU／mL、蛋白酶活力为15Iu／mL、25IU／mL时对UHTSfL苦味值的影响显著（P〈0．05）；原料gLpH值为6．7和3.5％2冷藏条件下，蛋白酶、脂肪酶活性较高，不利于uHT乳长期贮存、综上研究，原料乳中嗜冷菌数过多会严重影响uHT乳品质和风味；低温贮藏条件下，嗜冷菌产生的脂肪酶和蛋白酶会破坏UHT乳品质，因此不建议长期低温保存uHT乳、Raw milk pollution arised by Psychrophilic Bacteria can greatly shorten the shelf-life of UHT milk.The damaging heat-resistant lipase and protease secreted by Psychrophilic Bacteria can still remain after sterilization during UHT production. The distribution of Psychrophilic Bacteria has regional features. In this study, Psychrophilic Bacterium isolated from eight pastures of Mengniu milk industry were investigated on their impact upon UHT milk. Psychrophilic Bacterium screened out were Pseudomonas, Micrococcus and Alkaligenes. Results showed that the number of Psychrophilic Bacteria in raw milk was larger from January to March, compared to the period from June to September, and the more Psychrophilic Bacterium existed in raw milk, the shorter shelf-life of UHT milk seemed to be. Other results showed that, 10℃FU/ml of Psychrophilic Bacteria could obviously lead to corruption of UI-IT milk, simutaneously generating bitter taste（P〈0.05）. Specifically in enzyme activity for lipase of 10IU/mL and protease of 15, 251U/mL had significantly effect on milk corruption （P〈0.05）. Also, pH 6.7 and 3-5℃ was not suitable for long-term storage of UHT milk, because under this condition the lipase and protease enzyme in UHT milk was still relatively high. In conclusion, excessive Psychrophilic Bacterium in raw milk would largely influence the quality and flavor of UHT milk, and low temperature may give rise to high-active lipase and protease for the damage of UHT milk, which is not suggested for the UHT milk storage.

关 键 词：嗜冷菌 UHT乳 乳品质 影响 

分 类 号：TS252.1[轻工技术与工程—农产品加工及贮藏工程]