Development and creation of food materials having novel characteristics by thermal treatment of food proteins

乳清蛋白由β-乳球蛋白（βLG）、α-乳白蛋白和血清白蛋白βLG等球状蛋白组成，是乳清蛋白在加热时聚集和凝胶化的主要蛋白质成分。一个βLG分子由162个氨基酸残基组成，并具有两个二硫键（S S），位于Cys^<66>-Cys^<160>和Cys^<106>-Cys^<119>，以及位于Cys^<121>的游离巯基。在生理条件下，这种球状蛋白以二聚体的形式存在，由9条β链组成反平行的β片。βLG有7个变体，其中以变体A和变体b居多。βLG变体A （βLG A）贯穿了整个研究。βLG A分子在受热时会聚集，分子间二硫键似乎在这种分子聚集中起着重要作用。βLG A的聚集取决于pH、盐浓度和加热温度。虽然游离巯基残基对β - lg在加热过程中的分子聚集的重要性是公认的，但在热变性和分子间二硫化物形成聚集过程中发生的更多事件尚未得到详细的揭示。为了揭示热诱导βLG分子聚集的机理，阐明巯基残基的参与是很重要的。乳清蛋白因其高凝胶性和乳化性而被广泛用作食品原料。蛋白质在分子水平上的构象变化对食品蛋白质的功能特性有很大影响。凝胶的形成通常是由蛋白质分子在食物系统中加热形成的网状结构引起的。加热引起蛋白质分子的构象变化。变性蛋白分子之间的相互作用是构建三维网络结构所必需的。本研究考察了βLG A在加热过程中的构象变化，特别是其可逆性和pH依赖性。此外，还分析了分子间通过二硫桥和其他非共价力的相互作用，揭示了分子聚合和凝胶化的机理。少

Milk whey protein consists of globular proteins such as β-lactoglobulin (βLG), α-lactalbumin, and serum albumin βLG, the major protein component, is largely responsible for the aggregation and gelation of whey protein on heating. A βLG molecule consists of 162 amino acid residues and has two disulfide (S S) bonds, at Cys^<66>-Cys^<160> and Cys^<106>-Cys^<119>, and a free sulfhydryl group at Cys^<121>. Under physiological conditions, this globular protein exists as a dimer consisting of antiparallel β-sheets formed by nine β-strands. βLG has seven variants and most of them are variant A and B.βLG variant A (βLG A) was used throughout this study. βLG A molecules aggregate when they are heated, and intermolecular disulfide bonds seem to play an important role for such molecular aggregation. Aggregation of βLG A depends on pH, salt concentration, and heating temperature. Although the importance of free sulfhydryl residue is accepted for molecular aggregation of βLG on heating, the molecula … More r events occurring on the thermal denaturation and aggregation via intermolecular disulfide formation have not been revenaled in detail. To reveal the mechanism of heat-induced molecular aggregation of βLG, it is important to clarify the participation of sulfhydryl residue. Milk whey protein is widely used as a food ingredient due to its high gelation and emulsification ability. Change in the conformation of the protein at molecular level strongly influences the functional properties of the food protein. The gel formation is usually induced by formation of network structure with protein molecules when heated in the food system. Heating induces the conformational change in a protein molecule. The molecular interaction among the denatured protein molecules is necessary for the construction of the three-dimensional network structure. In the present study the conformational change of βLG A by heating was examined, particularly its reversibility and pH dependency. In addition, the molecular interactions through disulfide bridge and other non-covalent forces have been analyzed to reveal the mechanism of molecular polymerization and gelation. Less