β-casein (β-CN) comprises a major portion of milk caseins and are present as several genetic variants. In this study, we investigated the effects of the β-CN A² variant versus the A¹ variant on the calcium distribution, acid gelation and foaming properties of milk, and the microstructure of acid milk gels. The results showed that milk containing the β-CN phenotype A²A² had a higher proportion of free ionic calcium, enhanced foam formation capability and required a longer time for gelation to occur. The storage modulus at the end of fermentation was significantly lower for β-CN A²A² milk gel compared with that from β-CN A¹A¹ milk. The microstructures of the gels characterised by both confocal microscopy and Cryo-SEM demonstrated the differences in the gel porosity and protein strand thickness. The more porous microstructure and thinner protein strands in the β-CN A²A² milk gel resulted in a lower gel strength compared to β-CN A¹A¹ milk gel. These findings provide new insights to the subtle differences in the physical properties of milk containing β-CN A²A² and A¹A¹ phenotypes, which could support dairy producers in the development of new dairy products with different functional properties.

β-酪蛋白（β-CN）占牛奶酪蛋白的主要部分，以几种遗传变异形式存在。在这项研究中，我们研究了β-CNA ²变体与A ¹变体对牛奶中钙的分布，酸凝胶化和起泡特性以及酸牛奶凝胶的微观结构的影响。结果表明，含有β-CN表型A ² A ^2的牛奶具有较高比例的游离离子钙，增强了泡沫形成能力，并且需要更长的时间才能发生胶凝。与β-CNA ¹ A ¹相比，β-CNA ² A ²乳凝胶发酵结束时的储能模量明显更低。牛奶。共聚焦显微镜和Cryo-SEM表征的凝胶的微观结构证明了凝胶孔隙率和蛋白质链厚度的差异。与β-CNA ¹ A ¹乳凝胶相比，β-CNA ² A ²乳凝胶中具有更多的多孔微结构和较细的蛋白质链，因此凝胶强度较低。这些发现为含有β-CNA ² A ²和A ¹ A ¹表型的牛奶的物理特性之间的细微差异提供了新的见解，这些差异可以支持乳制品生产商开发具有不同功能特性的新型乳制品。