Characterization of polyphenol-protein reactions in model systems and foods

酚类化合物是植物性食品中的品质决定化合物，因其对人体健康的有益作用而被广泛用作功能性食品配料。为此，它们可以从各种来源中提取，如茶叶、葡萄皮和种子、苹果，甚至药用植物。由于失去了天然保护基质，酚类物质在加工过程中暴露在氧气中，因此可能被氧化成不稳定的活性中间体。这些所谓的醌可以与许多食物成分相互作用，特别是与蛋白质相互作用。这类反应的技术和生化后果是多方面的，例如蛋白质的交联、酶活性的变化、氨基酸和酚类的生物利用度降低，以及食物蛋白质的免疫学性质的改变。虽然该项目的主要目的是利用高度复杂的分析技术表征酚类化合物和蛋白质反应形成的产物，但更好地了解酚类化合物的稳定性及其与其他食品成分的相互作用将使我们能够得出优化(功能性)食品生产工艺的结论，并在一定程度上能够估计潜在的不利影响。鉴于功能食品在整个食品市场中的重要性与日俱增，对其生物活性成分的反应性进行调查是必要的。了解蛋白质与酚类物质反应后的变化也可能导致低过敏性食物的生产。因此，预计拟议调查的结果将促进跨学科研究，特别是在食品化学和食品技术、营养科学、毒理学和免疫学领域。

Phenolic compounds are quality determining compounds in plant-derived foods and are widely used as functional food ingredients, owing to their supposed beneficial effects on human health. For this purpose they are extracted from various sources such as tea leaves, grape skins and seeds, apples, and even medicinal plants. Being deprived of their natural protecting matrices, the phenolics are exposed to oxygen during processing and may therefore be oxidized to instable, reactive intermediates. These so-called quinones can interact with a number of food constituents, in particular with proteins. The technological and biochemical consequences of such reactions are manifold, e.g. crosslinking of proteins, changes in enzyme activities, reduced bioavailability of both amino acids and phenolics, and modifications of the immunological properties of food proteins. While it is the primary aim of this project to characterize the products formed by the reaction of phenolic compounds and proteins using highly sophisticated analytical techniques, a better understanding of the stability of phenolic compounds and their interactions with other food constituents would allow conclusions on the optimization of processes for the production of (functional) foods and would also, to a certain extent, allow the estimation of potential adverse effects. In view of the growing importance of functional foods within the overall food market, investigations into the reactivity of their bioactive constituents are essential. Knowledge of the alterations of proteins by reaction with phenolics may also lead to the production of hypoallergenic food. Thus, it is anticipated that the results of the proposed investigations will stimulate cross-disciplinary research, in particular in the fields of food chemistry and food technology, nutritional science, toxicology, and immunology.