驼乳乳清蛋白多态性的研究

Study on the polymorphism of camel milk whey protein

以生鲜驼乳和不同干燥方式生产的驼乳粉为材料,用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和反相高效液相色谱(RP-HPLC)表征采集时间、采样地点、脂肪含量、干燥方式对驼乳乳清蛋白多态性的影响。结果表明,同一地点同一个体的驼乳在不同月份之间的乳清蛋白有统计学差异,说明驼乳中的蛋白质变化水平受季节的影响。不同地点采集的驼乳中乳清蛋白在同一个月份也有统计学差异,说明不同采样地点对鲜驼乳乳清蛋白的多态性都具有一定的影响。乳粉加工的干燥过程会影响驼乳乳清蛋白的多态性,干燥后得到的各类驼乳粉中乳清蛋白的组分均发生了不同程度的热损伤。乳粉中乳脂对乳清蛋白也具有一定的保护作用。驼乳粉乳清蛋白中蛋白组分相对丰度的变化不仅与原料乳中脂肪含量有关,也与乳粉的热加工方法、乳清蛋白中的热敏蛋白、加热杀菌有关。且与低温真空干燥法相比,喷雾干燥法对驼乳粉中乳清蛋白的多态性变化影响更为显著,对乳铁蛋白和α-乳白蛋白的破坏严重。用RP-HPLC方法能够快速检测驼乳粉中α-乳白蛋白,表明其可以作为驼乳清蛋白多态性的最佳标识物。

In this experiment,we used raw camel milk and camel milk powder produced by different drying methods to characterize the effects of lactation period,sampling location,and fat content drying method on whey protein polymorphism of camel milk by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and reversed-phase high performance liquid chromatography(RP-HPLC).The results showed significant differences in whey protein between months of lactation in camel milk from the same individual at the same location,suggesting that the level of protein variation in camel milk is influenced by the season.There were also significant differences in whey protein in camel milk collected from different locations in the same month of lactation,indicating that both lactation period and sampling location have an effect on the polymorphism of whey protein in fresh camel milk.The drying process of dairy powder processing affected the polymorphism of camel milk whey protein,and different degrees of thermal damage occurred in the components of whey protein in all types of camel milk powder obtained after drying.Milk fat in dairy powder also has a protective effect on whey protein.The changes in the relative abundance of protein fractions in whey protein of camel milk powder were not only related to the fat content in raw milk,but also related to the thermal processing method of milk powder,heat-sensitive protein in whey protein,and heating sterilization.And compared with the low-temperature vacuum drying method,the spray drying method had more significant effects on the polymorphic changes of whey protein in camel milk powder,and the damage to lactoferrin andα-lactalbumin was serious.The rapid detection ofα-lactalbumin in camel milk powder by RP-HPLC method indicated that it could be the best marker for the polymorphism of camel whey protein.