Physicochemical Characteristics And Yoghurt Making Of Simmental Crossbred Cattle Milk

Simmental crossbred cattle milk is a high nutritional value of raw milk,but the current study of Simmental crossbred cattle milk was very little,and there were seldem references on the physicochemical characteristics of Simmental crossbred cattle milk.Therefore,this research aims to scientifically evaluate the nutritional value and physical characteristics of Simmental crossbred cattle milk,and provide a basis for the development of the milk.This thesis mainly studied the nutritional quality of Simmental crossbred cattle milk,the separation and quantification of seven genetic variants of protein in Simmental crossbred cattle milk,the physical characteristics of Simmental crossbred cattle milk,and the yogurt quality of Simmental crossbred cattle milk.The main research methods,results and conclusions were as follows:1.Seasons and varieties could influence on the physicochemical properties of Simmental crossbred cattle milk.The results showed a great variation on the physicochemical properties throughout the 12 months.In generally,the contents of protein,fat and lactose in the two kinds of milk were higher in winter and spring seasons than those in summer and autumn seasons.Comparing Simmental crossbred cattle milk with Holstein milk,the nutritional quality of Simmental crossbred cattle milk was better one,Simmental crossbred cattle milk was a high quality of raw milk.2.A RP-HPLC method was built for the separation and quantification of seven genetic variants of protein in Simmental crossbred cattle milk.The linear relationship of seven proteins,namely κ-CN,αs2-CN,αs1-CN,β-CN,β-LgB,α-La,β-LgA,was good in the corresponding concentration range.The correlation coefficient was between 0.9983 and 0.9999,respectively.And the recovery rate was between 81%and 115%,respectively.The method was high precision,good repeatability and reproducibility.There were some differences in major proteins composition between Simmental crossbred cattle milk and Holstein milk.The major protein components of Simmental crossbred cattle milk were related with seasons.And the contents of casein and whey were not stable value when the seasons changed during our reasearching 12 months.3.The two kinds of milk some physical characteristics,such as,buffering capacity,stability factor,surface tension,particle size distribution and Zeta potential were studied and compared.Their physical characteristics were significant differences.The buffer capacity of Simmental crossbred cattle milk was higher,and the sizes of protein and fat globules in Simmental crossbred cattle milk were bigger.4.Some parameters including fermentation kinetics,texture properties,rheological properties and syneresis,for making yoghurt by the two kinds of milk,were researched also.Simmental crossbred cattle yoghurt exhibited a higher titratable acidity,lower syneresis,higher consistency coefficient K and slightly lower rheological index n.Moreover,the viscoelastic properties and texture properties of Simmental crossbred cattle yogurt are better than that of Holstein yogurt.It is show that there are different sensory properties in these two yoghurts,Simmental crossbred cattle yogurt could be further investigated for the development of new fermented dairy products for the market.