为探究牦牛乳酪蛋白胶束的理化特性,揭示牦牛乳的加工特异性,以黑白花牛乳为对照,分别采用等电点沉淀法和超速离心法制备牦牛乳酪蛋白胶束,并通过高效液相色谱仪、激光粒度仪、透射电子显微镜等测定了酪蛋白胶束的组成、粒径、微观结构等特性。结果表明:超速离心法制备牦牛乳酪蛋白胶束(U-Yak)的得率为13.14 g/100 mL,显著高于酸沉淀法(A-Yak,9.81 g/100 mL);U-Yak蛋白质含量为39.95%,Ca含量为1 488.63 mg/L,水分含量为59.18%,与A-Yak差异显著;U-Yak与A-Yak二级结构差异主要体现在β-折叠(U-Yak 45.0%,A-Yak 43.7%)和β-转角(U-Yak 47.6%,A-Yak 46.7%)。透射电镜结果显示U-Yak粒径更小,衬度更高。试验结果为制备酪蛋白胶束及胶束的实际应用提供了重要参考。
The aim of this study was to investigate the physicochemical properties of yak casein micelles and exploit the deep-processed products.Yak and cow casein micelles prepared by acid precipitation and ultracentrifugation methods were used as materials, and composition, particle size, protein structure, microstructure of these materials were determined by using HPLC, laser particle size analyzer, FTIS, transmission electron microscopy (TEM).The results showed that yield of yak casein micelles (U-Yak) prepared by ultracentrifugation was 13.14 g/100 mL, which was markedly higher than that prepared by acid precipitation method (A-Yak, 9.81 g/100 mL).Furthermore, protein, Ca content, moisture content of U-Yak was 39.95%, 1 488.63 mg/L, 59.18%, respectively, which were significantly different of those of A-Yak.The secondary structure, such as β-folding (U-Yak 45.0%, A-Yak 43.7%) and β-turning (U-Yak 47.6%,A-Yak 46.7%), was different between U-Yak and A-Yak.TEM images showed that particle size of U-Yak was smaller than that of A-Yak, and contrast of U-Yak’s TEM image was higher than that of A-Yak’s.These findings provide valuable reference point for the preparation of casein micelles and their practical applications.The results provide valuable reference for production of casein micelles.
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