Milk Protein Fractions: Assessment of Bioactivities for Applications in Functional Foods

牛奶蛋白越来越多地被用于各种功能食品和营养食品中，包括蛋白质饮料混合物、运动餐、蛋白质棒、高蛋白饼干和可咀嚼的蛋白质片。最常用的成分是乳清蛋白浓缩物和乳清分离物，然而最近牛奶蛋白制备性分级的进展为功能食品市场带来了更多的产品，包括α-、β-和kappa-酪蛋白、β-乳球蛋白、α-乳清蛋白、乳铁蛋白、糖巨肽和其他次要的蛋白质和多肽。主要乳蛋白组分(酪蛋白和乳清蛋白)的生物活性已经通过动物模型和人类进行了研究。另一方面，对少量牛奶蛋白质组分的研究可能进一步解释酪蛋白和乳清蛋白影响血糖和食物摄入量的机制。此外，单个乳蛋白组分的使用可能为调节葡萄糖代谢的内分泌机制和相关的生理功能提供一些新的见解。另一个在很大程度上未被探索的领域是食品加工，如高温，对牛奶蛋白质组分的生物活性的影响。虽然牛奶蛋白的生物活性是通过在标准状态下制备的蛋白质溶液进行实验来确定的，但许多添加了蛋白质的食品都要经过热处理或加压处理，以保持它们的保鲜或质构变化。该计划的主要目的是阐明单个牛奶蛋白组分的生物活性，评估它们的生物活性，并制定添加生物活性牛奶蛋白组分的功能食品的原型。利用小型实验动物，将评估与能量平衡和血糖控制有关的生理机制，以响应纯牛奶蛋白质组分的摄入。然后，这些具有生物活性的组份将在人类参与者身上进行测试，以确定降低血糖或抑制食物摄入所需的最低有效剂量。该项目的最后一步将包括配制含有有效剂量生物活性牛奶蛋白质组分的功能食品，并用训练有素的品尝小组对其进行感官分析。另一项生物功效评估将用于加工的原型，以确定食品加工是否改变了它们的生物效益。该计划有可能在未来扩大，并测试用于功能食品的其他食品成分的生物活性。

Milk proteins are increasingly used in a variety of functional foods and nutraceuticals including protein drink mixes, sport meals, protein bars, high-protein cookies and chewable protein tablets. The most commonly used ingredients are represented by whey protein concentrates and isolates however the recent advances in preparative fractionation of milk protein bring more products to the functional food market including alpha-, beta- and kappa-caseins, beta-lactglobulin, alpha-lactalbumin, lactoferrin, glycomacropeptide and other minor proteins and peptides. The biological activity of major milk protein fractions (casein and whey protein) has been investigated using animal models and humans. On the other hand, the study of minor milk protein fractions may further explain the mechanisms by which casein and whey protein influence blood glucose and food intake. Furthermore, the use of individual milk protein fractions may provide some new insight on the endocrine mechanisms regulating glucose metabolism and relevant physiological functions. Another largely unexplored area is the effect of food processing, such as high temperature, on the biological activity of milk protein fractions. While biological activities of milk protein are determined in experiments with protein solutions prepared under the standard state conditions, many foods with added proteins are processed with heat treatment or pressurizing required for their preservation or textural changes. The main objective of this program is to elucidate the biological activity of individual milk protein fractions, assess their bioactivities and formulate the prototypes of functional foods with added bioactive milk protein fractions. Using the small laboratory animals, the physiological mechanisms related to energy homeostasis and blood glucose control in response to the intake of pure milk protein fractions will be evaluated. Then the fractions with proven biological activity will be tested in human participants to establish the lowest efficacy dose required to reduce blood glucose or suppress food intake. The final step of the project will include the formulation of functional foods containing the effective dose of bioactive milk protein fraction and their sensory analysis with a trained taste panel. Another evaluation of biological efficacy will be used for the processed prototypes to determine whether food processing changes their biological benefits. This program has a potential to expand in the future and test the biological activity of other food ingredients used in functional food products.