Centre for Food and Microbial Technology and Leuven Food Science and Nutrition Research Centre, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
J Agric Food Chem. 2010 Oct 13;58(19):10761-7. doi: 10.1021/jf102575r.
When gliadin, a mixture of wheat storage proteins containing only intramolecular disulfide (SS) bonds, is heated at high temperatures and preferably at alkaline pH, the SS bonds are cleaved by β-elimination reactions leading to decreased cystine levels and the generation of dehydroalanine (DHA) and free sulfhydryl (SH) groups. DHA and the free SH group of cysteine can further react to form the irreversible cross-link lanthionine (LAN). The kinetics of this reaction were studied by heating model systems containing gliadin at different pH values (pH 6.0, 8.0 and 11.0) at temperatures up to 120 °C. Multiresponse modeling was applied to simultaneously describe the course of the reaction partners, intermediates and products. The estimated kinetic parameters indicate that the reaction rate constant for the elimination reaction increases with temperature and pH. Moreover, the predominant reaction consuming the intermediary DHA is the cross-link with cysteine to form LAN following second-order reaction kinetics. The corresponding reaction rate constant is less dependent on temperature and pH. Use of the proposed kinetic model to estimate reaction product concentrations in cereal-based foods allowed us to conclude that the β-elimination reaction may be less important during, e.g., bread making, but may well contribute to gluten network formation during the production of soft wheat products. It may also well be relevant in the production of bioplastics made from gluten.
当麦醇溶蛋白（一种仅包含分子内二硫键（SS）的小麦贮藏蛋白混合物）在高温下加热，最好在碱性 pH 值下，β-消除反应会导致 SS 键断裂，半胱氨酸水平降低，并生成脱氢丙氨酸（DHA）和游离巯基（SH）基团。DHA 和半胱氨酸的游离 SH 基团可以进一步反应，形成不可逆的交联赖氨酰（LAN）。通过在不同 pH 值（pH 6.0、8.0 和 11.0）下加热含有麦醇溶蛋白的模型系统，在高达 120°C 的温度下研究了该反应的动力学。多响应建模被用于同时描述反应伙伴、中间体和产物的过程。估计的动力学参数表明，消除反应的速率常数随温度和 pH 值的升高而增加。此外，消耗中间 DHA 的主要反应是与半胱氨酸的交联，形成 LAN，遵循二级反应动力学。相应的反应速率常数对温度和 pH 值的依赖性较小。使用所提出的动力学模型来估计谷物食品中的反应产物浓度，使我们能够得出结论，例如在面包制作过程中，β-消除反应可能不太重要，但可能对软质小麦产品生产过程中的面筋网络形成有贡献。它在由面筋制成的生物塑料的生产中也可能是相关的。
