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

牛奶乳清蛋白由球状蛋白组成，如β-乳球蛋白(β-Lg)、α-乳清蛋白和血清白蛋白β-Lg是乳清蛋白加热时聚集和凝胶的主要蛋白质组分。βLG分子由162个氨基酸残基组成，有两个二硫键(S S)，分别位于Cys^&lt；66&gt；-Cys^&lt；160&gt；和Cys^&lt；-Cys^&lt；119&gt；以及Cys^&lt；121&gt；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-链组成的反平行β-Sheet组成。βLG有7个变种，其中大部分是变种A和B。βLG变种A(βLG A)在整个研究过程中被使用。βlgA分子在受热时聚集，分子间二硫键似乎在这种分子聚集中起着重要作用。βlgA的聚集与pH、盐浓度和加热温度有关。尽管自由羟基残基对于βLG在加热时分子聚集的重要性是被接受的，但分子…通过分子间二硫键形成的热变性和聚集过程中发生的更多r事件还没有被详细报道。为了揭示βLG热诱导分子聚集的机理，弄清巯基残基的参与是重要的。乳清蛋白具有很强的凝胶性和乳化性，被广泛用作食品配料。蛋白质在分子水平上构象的变化强烈影响食物蛋白质的功能特性。凝胶的形成通常是由于在食品体系中加热时蛋白质分子形成网络结构而引起的。加热诱导蛋白质分子的构象变化。变性蛋白质分子之间的分子相互作用是构建三维网络结构所必需的。本研究考察了βlgA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，还分析了通过二硫键和其他非共价力的分子相互作用，揭示了分子聚合和凝胶的机理。较少

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