| With the development of ceramic membrane technology in dairy industry, the extensive use of microfiltration technology is not only in removal of bacteria and somatic cell count, cheese processing, fat removal of whey, purification of cheese brine, but also in selective fractionation of fat.One of the results of mastitis in dairy cows is an increase in the somatic cell count in the milk. 30 Holstein dairy cows in a farm of Peking suburb were conducted during summer. The results showed that there was significantly positive relationship among pH value, conductivity, protein content and somatic cell count (p<0.05), significantly negative relationship among fat content, casein content and somatic cell count (p<0.05) and no siginificant relationship among total solids, lactose and somatic cell count. The Dairy Herd Improvement System data from March 2007 to February 2008 showed that the risk and the ratio of mastitis were much higher in summer, which resulted a great difference in milk composition. It was not easy for farm to control the quality and composition of bovine milk according to Chinese cow nutrition and feeding condition, the dairy manufacturer must take measures to promote the quality and homogeneity of dairy products.Only High quality raw milk can produce high quality Mozzarella cheese. In order to study the effect of different somatic cell count milk on the proteolytic, lipolytic, functional characteristics, colour and sensory properties of Mozzarella cheese, the cheesemilk contains somatic cell count at significant low (after 1.4μm microfiltration), low (300 000 cell/mL) and high levels(600 000 cell/mL). The result indicated that somatic cell count did not significantly affect the proteolysis, although the high somatic cell count cheese was a little higher (+0.05%). The reason why the result was not identical to the previous results may be that Cheddar cheese is ususlly matured at 6~10℃for a period ranging from 6 months to 2 years, and this long period would allow the prolonged action of proteolytic enzyme in Cheddar cheese during ripening. The result indicates that somatic cell count lower than 600 000cells/mL is not an important factor for Mozzarella cheese quality.The optimal operating conditions for concentrating casein using 0.14μm ceramic membrane were 5 m/s and 0.5 Bar at 50℃. The sterile and non-fat microfiltration permeate,―ideal whey‖has a high added value potential in whey products processing. Use of 0.14μm microfiltration and control cheese milk for manufacturing low moisture Mozzarella cheese were studied during 60 day, including cheese chemical changes, component recovery, oiling off, meltability, stretchability and texture. This work demonstrated that microfiltration was a new way to standardise cheesemilk, which has advantages in saving production space (-23 %), decreasing rennet addition (-50 %), increasing yield (protein recovery +13.27 %), increasing homogenity of product and simplifying whey treatment. Mozzarella cheese, which functionality was much more important than flavor, the lower proteolysis may be better for stability and shelf life.The expressible serum and the scanning electron microscopy were used to assess the effect of microfiltration on the Mozzarella cheese during 10-day storage at 4℃. The expressible serum/moisture content in both Mozzarella cheese decreased during ripening. The content of expressible serum/moisture in microfiltration Mozzarella cheese (-0.6 %) was less than control Mozzarella cheese and the buffering capacity was higher (+6.74 %). The microscopy showed that the casein matrix absorbed free water and the expressible serum channel lessened during ripening time. The casein matrix was more smooth and homogeneous and the channel was more porous in control Mozzarella cheese, which were correlated with the nature of cheesemilk. With the development of micsroscopy technology and the decrease of detection cost, the microscopy technology will be a fast and sensitive analytical measure.
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