β-酪蛋白具有低温溶出的特性。本文通过低温微滤处理制备了β-酪蛋白脱除率为10、20、30%的牛乳，运用HPLC、场发射扫描电镜、流变仪以及激光共聚焦研究了这些牛乳的蛋白组分、酪蛋白胶束结构及凝乳性质变化。结果表明：脱脂乳与低温微滤处理得到的牛乳样品的脂肪含量，总钙含量及pH值无显著性差异，但总蛋白含量有显著性差异，其中κ-酪蛋白和αs2-酪蛋白浓度无差异，αs1-酪蛋白浓度有显著差异，但低温处理样品间αs1-酪蛋白浓度则无差异，β-酪蛋白及乳清蛋白浓度差异极显著，其浓度随处理时间增加显著减小。脱脂乳与牛乳样品均可形成致密的具有空隙的凝胶结构，且其酸凝乳及酶凝乳所表现的流变学变化趋势相似，但随着β-酪蛋白脱除率升高，表征凝乳块硬度的最大G'逐渐下降，凝胶结构逐渐变疏松，出现的孔隙则更大更多。

β-Casein (β-CN) dissociates from milk during low-temperature treatment. Skim milk was subjected to low-temperature microfiltration to obtain milk samples with β-CN removal ratios of 10, 20, or 30%. High-performance liquid chromatography (HPLC), field emission scanning electron microscopy, rheometry, and laser scanning confocal microscopy were used to study the changes in protein composition, CN micellar structure, and coagulation properties of these milk samples. The results showed no significant differences between skim milk and the milk sample treated with low-temperature microfiltration in fat content, total calcium content, and pH value, but significant differences were found in total protein content. Among proteins, no difference was found in κ-CN and αs2-CN concentrations, and significant differences were found for αs1-CN concentrations. However, although no difference was found in αs1-CN concentration among the samples treated by low-temperature microfiltration, highly significant differences were found in the concentrations of β-CN and whey protein, and these were significantly decreased with increasing processing time. Both skim milk and treated milk samples could form a compact and porous gel structure, and the trend in the rheological changes of the coagulations induced by glucono-delta-lactone (GDL) and GDL combined with chymosin were similar. However, with increasing β-CN removal ratio, the maximum G′ characterizing the hardness of curds gradually decreased, the curd structure gradually became loose, and more pores with a larger size appeared.

国家自然科学基金项目（31371803）；江苏省产学研联合创新资金（BY2015019-34）