Organic acids in bread-making affecting gluten structure and digestibility

Abstract

Although wheat gluten has remarkable technological properties, it can induce adverse immune reactions in susceptible individuals, such as wheat allergy and celiac disease. Technological processing and some additives on bread formulation can modify gluten physicochemical structure, but the knowledge about the impacts on the digestibility and immunogenicity of gluten is limited. The present study aimed to study the effect of adding organic acids (acetic or ascorbic) on dough rheological properties and bread technological characteristics. In addition, breads were subjected to in vitro digestion and the digesta were analyzed by confocal microscopy, SDS-PAGE and ELISA immunoassay. Acetic acid resulted in a decrease in dough development time up to 44 % and a reduction in stability up to 20 %. Ascorbic acid, present in vinegar, on the other hand, increased elastic modulus (G') and resistance to extension of dough. After the in vitro digestion, SDS-PAGE indicated that protein degradation started in the gastric phase, with the generation of low molecular weight peptides. Accordingly, ELISA immunoassay suggested a great reduction in immunogenic gliadin content from oral to gastric phase. At the end of the intestinal phase, samples with ascorbic acid did not differ from the control, while vinegar addition indicated a reduction in gluten immunogenicity with a reduction of about 44 % in immunogenic gliadin content compared to the control. Results show a window of opportunity in the modulation of wheat bread formulation with reduced allergenicity, while maintaining the technofunctional properties.

Keywords: Acetic acid; Ascorbic acid; Immunogenicity; In vitro digestion; Protein structure; Technological modifications; Wheat bread.