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

乳蛋白越来越多地用于各种功能性食品和营养保健品，包括蛋白饮料混合物、运动餐、蛋白棒、高蛋白饼干和咀嚼蛋白片。最常用的成分以乳清蛋白浓缩物和分离物为代表，然而，乳蛋白制备分级的最新进展为功能性食品市场带来了更多产品，包括α-、β-和κ-酪蛋白、β-乳球蛋白、α-乳白蛋白、乳铁蛋白、糖巨肽和其他次要蛋白质和肽。主要乳蛋白组分（酪蛋白和乳清蛋白）的生物活性已使用动物模型和人类进行了研究。另一方面，对乳中微量蛋白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的机制。此外，个别乳蛋白组分的使用可能会提供一些新的见解调节葡萄糖代谢和相关的生理功能的内分泌机制。另一个尚未探索的领域是食品加工（如高温）对乳蛋白组分生物活性的影响。虽然牛奶蛋白的生物活性是在标准状态条件下制备的蛋白质溶液的实验中确定的，但许多添加蛋白质的食品都经过热处理或加压处理，以保持其保存或质地变化。该计划的主要目标是阐明单个乳蛋白组分的生物活性，评估其生物活性并配制添加生物活性乳蛋白组分的功能性食品原型。使用小型实验室动物，将评价与能量稳态和血糖控制相关的生理机制，以响应纯乳蛋白组分的摄入。然后，将在人类参与者中测试具有已证实的生物活性的组分，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含有有效剂量的生物活性乳蛋白组分的功能性食品的配方，以及由训练有素的品尝小组进行感官分析。生物功效的另一项评估将用于加工原型，以确定食品加工是否改变其生物学益处。该计划有可能在未来扩大，并测试功能性食品中使用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.