Effect of Regulating Corn Glutelin Peptides via the Plastein Reaction on Its Physicochemical Characteristics and the Quality of Baked Bread

Corn glutelin is the main protein component of corn processing by-products, with a wide range of sources and low cost. However, its hydrophobic molecular structure, poor solubility, foaming and emulsifying properties limit its application in the food industry. Enzymatic hydrolysis can effectively improve its solubility, but the functional properties of hydrolysis products still need further improvement. The plastein reaction is a mild enzymatic modification method that can recondense small peptides in hydrolysis products under the catalysis of protease, meanwhile introducing exogenous amino acids to achieve the targeted regulation of product structure and function. Corn glutelin was hydrolyzed to obtain corn glutelin hydrolysate (CGH). Corn glutelin hydrolysate (CGH) with exogenous amino acids (valine, tyrosine, cysteine and threonine) was mediated by plastein reaction in order to gain modified products enriched with these amino acids, which are Val-CGH, Tyr-CGH, Cys-CGH and Thr-CGH, respectively. This study mainly investigated the functional properties and structural characteristics of these modified peptides. Simultaneously, the modified peptides with superior solubility, foaming ability and foaming stability were screened and applied to bread formulas to evaluate potential application of plastein reaction modifiers in the baking field. The effects of modified peptides on the specific volume of dough, texture and sensory properties of bread were assessed. Among the modified peptides, Cys-CGH had the best foaming property and foaming stability, and fine solubility. Compared with CGH, the solubility of Cys-CGH increased by 4.16%, foaming performance (FC) increased by 41.5%, foaming stability at 10 min (FS10) increased by 10.44%, foaming stability at 20 min (FS20) improved by 12.67%, and bubble stability at 30 min (FS30) improved by 16.63%. In addition, the baking loss rate of the bread sample containing 0.5% Cys-CGH decreased by 0.93%, the specific volume enhanced by 0.27 cm3/g, the hardness lowered by 0.3 N, the springiness raised by 1.03, the chewiness improved by 7.5 N. The sensory acceptance of bread samples with 0.5% Cys-CGH was significantly optimized. In brief, this also demonstrates that adding modifiers with good functional properties can improve the quality of baked products, highlighting their potential as a green food additive in baked goods.