Innovations in multi-grain bread fermentation: role of lactic acid bacteria in enhancing quality and modulating glycemic response

Multigrain bread is valued for its diverse nutrients and potential for a lower glycemic response, depending on grain composition, particle structure, and processing; however, incorporating multiple grains often weakens dough structure, loaf volume, texture, and consumer acceptability. Fermentation with lactic acid bacteria (LAB), particularly in association with yeasts, offers a promising strategy to improve both technological quality and functional potential. This review evaluates the role of LAB and LAB-yeast fermentation in enhancing the quality, nutritional value, flavor, shelf life, and glycemic relevance of multigrain bread. Evidence indicates that LAB-yeast interactions may be synergistic, neutral, or competitive and, when appropriately selected, can improve gas retention, dough expansion, crumb texture, flavor complexity, mineral bioavailability, and storage stability through acidification, enzymatic activity, antimicrobial effects, and structural modification of the dough matrix. Fermentation also promotes the release, transformation, and bioaccessibility of functional compounds, including phenolic acids, organic acids, bioactive peptides, and exopolysaccharides. These changes may support glycemic regulation by modulating gut microbiota and immune responses, enhancing antioxidant and insulin-related pathways, and reducing digestive enzyme activity and glucose availability. Overall, LAB-based fermentation represents a promising, matrix-dependent approach for developing high-quality functional multigrain breads with improved acceptability and potential benefits for glycemic control.