In order to improve the quality of UHT milk, high somatic cell count (SCC) and low SCC raw milk were degermed by microfiltration (MF) with 1.4 /um ceramic membrane. Four groups of milk were obtained: low SCC milk, MF low SCC milk, high SCC milk and MF high SCC milk. Then the four groups of milk were sterilized with ultra high temperature (UHT) to prepare four groups of UHT milk, which were stored in 37℃ and the quality was evaluated between the microfiltration and non-microfiltration groups. The results showed that in the high SCC and low SCC raw milk, residual bovine plasmin activity was 4.1% and 3.28% left respectively after UHT, while it was almost eliminated during the procedure of "MF+UHT". Both the quality indexes of the "MF+UHT" milk, including non-casein protein (NCN), Ph value, acidity and fat globule particle size, changed littler than UHT milk without MF and the quality kept better. Relative to the low SCC groups, the quality improved much more in the high SCC groups through microfiltration. The results can provide a reference for the use of high somatic cell milk to produce high quality UHT milk.%为了提高UHT超高温灭菌乳的品质,利用孔径为1.4μm的纤维管状陶瓷膜对体细胞数量高低不同的2组原料乳进行微滤除菌,得到4组牛乳,分别为:低体细胞原料乳、低体细胞微滤乳、高体细胞原料乳和高体细胞微滤乳.然后对4组牛乳进行UHT灭菌处理,得到4种UHT乳,将其置于37℃下进行贮藏试验,通过试验对比了微滤和不微滤对于UHT乳品质的影响.结果表明:2组原料乳经UHT处理,纤溶酶活性分别残留了4.1％和3.28％,而在“微滤+UHT”的工艺组合下,乳中的纤溶酶活性未检出.与不微滤的2种UHT乳相比,2种微滤UHT乳在贮藏期间的非酪蛋白氮、pH值、酸度、脂肪球粒径等指标值的变化更小,其品质保持更好.相对低体细胞牛乳而言,微滤除菌对高体细胞牛乳所制备的UHT乳的品质改善作用更为明显.研究结果为利用高体细胞牛乳生产优质UHT乳提供参考.
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