Gluten Functionality Modification: The Effect of Enzymes and Ultrasound on the Structure of the Gliadin–Glutenin Complex and Gelling Properties

The broader application of gluten in both the food and non-food industries is limited by its lack of functional properties, such as solubility, foaming ability, and rheological characteristics. This study aimed to evaluate the physicochemical properties of proteins in various gluten products and to investigate the effects of enzymatic hydrolysis and ultrasound (US) treatment on wheat flour gluten yield, gliadin-glutenin complex structure, and gelation properties. The gelation properties of wheat gluten (GL)/pea protein (PP) treated with US and transglutaminase (TG) were studied. The results demonstrated that the ratio of low- to high-molecular-weight components in gliadins and glutenins significantly influenced the quality of commercial gluten products. A 90 min treatment of wheat flour with 24 TGU/100 g increased the yield of high-quality gluten by 32% while reducing the gliadin content by up to 6-fold. Additionally, a 30 min US treatment of 18-20% pure gluten suspensions yielded a sufficiently strong gel. The addition of PP isolate (80% protein) improved the texture of gluten gels, with the best results observed at a GL:PP ratio of 1:2. The application of TG increased the hardness, consistency, and viscosity of GL-PP gels by an average of 5.7 times while reducing stickiness. The combined TG and US treatments, along with the addition of PP, notably increased the levels of lysine, isoleucine, and tryptophan, thereby enhancing both the nutritional quality and amino acid balance of the final product.