Center for Dairy Research, University of Wisconsin-Madison, Madison 53706.
Center for Dairy Research, University of Wisconsin-Madison, Madison 53706.
J Dairy Sci. 2017 Dec;100(12):9916-9932. doi: 10.3168/jds.2017-13250.
Understanding the chemistry of milk and its components is critical to the production of consistent, high-quality dairy products as well as the development of new dairy ingredients. Over the past 100 yr we have gone from believing that milk has only 3 protein fractions to identifying all the major and minor types of milk proteins as well as discovering that they have genetic variants. The structure and physical properties of most of the milk proteins have been extensively studied. The structure of the casein micelle has been the subject of many studies, and the initial views on submicelles have given way to the current model of the micelle as being assembled as a result of the concerted action of several types of interactions (including hydrophobic and the formation of calcium phosphate nanoclusters). The benefits of this improved knowledge of the type and nature of casein interactions include better control of the cheesemaking process, more functional milk powders, development of new products such as cream liqueurs, and expanded food applications. Increasing knowledge of proteins and minerals was paralleled by developments in the analysis of milk fat and its synthesis together with greater knowledge of its packaging in the milk fat globule membrane. Advances in analytical techniques have been essential to the isolation and characterization of milk components. Milk testing has progressed from gross compositional analyses of the fat and total solids content to the rapid analysis of milk for a wide range of components for various purposes, such as diagnostic issues related to animal health. Up to the 1950s, research on dairy chemistry was mostly focused on topics such as protein fractionation, heat stability, acid-base buffering, freezing point, and the nature of the calcium phosphate present in milk. Between the 1950s and 1970s, there was a major focus on identifying all the main protein types, their sequences, variants, association behavior, and other physical properties. During the 1970s and 1980s, one of the major emphases in dairy research was on protein functionality and fractionation processes. The negative cloud over dairy fat has lifted recently due to multiple reviews and meta-analyses showing no association with chronic issues such as cardiovascular disease, but changing consumer misconceptions will take time. More recently, there has been a great deal of interest in the biological and nutritional components in milk and how these materials were uniquely designed by the cow to achieve this type of purpose.
了解牛奶及其成分的化学性质对于生产一致、高质量的乳制品以及开发新的乳制品成分至关重要。在过去的 100 年里，我们已经从认为牛奶只有 3 种蛋白质组分，发展到确定了所有主要和次要类型的牛奶蛋白质，并发现它们具有遗传变异。大多数牛奶蛋白质的结构和物理性质已经得到了广泛的研究。酪蛋白胶束的结构已经成为许多研究的主题，最初关于亚胶束的观点已经让位于当前的胶束模型，即胶束是由几种类型的相互作用（包括疏水性和磷酸钙纳米簇的形成）协同作用组装而成的。这种对酪蛋白相互作用的类型和性质的更好了解的好处包括更好地控制奶酪制作过程、生产更多功能性奶粉、开发奶油利口酒等新产品以及扩大食品应用。随着对蛋白质和矿物质的了解不断增加，对牛奶脂肪的分析及其合成也取得了进展，同时对牛奶脂肪球膜中脂肪的包装也有了更多的了解。分析技术的进步对于牛奶成分的分离和特性描述至关重要。牛奶测试已经从对脂肪和总固形物含量的粗略成分分析发展到对各种目的的牛奶进行快速分析，例如与动物健康相关的诊断问题。直到 20 世纪 50 年代，乳品化学研究主要集中在蛋白质分级、热稳定性、酸碱缓冲、冰点以及牛奶中存在的磷酸钙的性质等方面。在 20 世纪 50 年代到 70 年代之间，主要重点是确定所有主要蛋白质类型、它们的序列、变体、结合行为以及其他物理性质。在 20 世纪 70 年代和 80 年代，乳品研究的一个主要重点是蛋白质功能和分级过程。由于多项综述和荟萃分析表明，乳制品中的脂肪与心血管疾病等慢性问题没有关联，乳制品的负面形象最近有所改善，但改变消费者的误解需要时间。最近，人们对牛奶中的生物和营养成分以及这些物质如何被奶牛独特设计以达到这种目的产生了极大的兴趣。
