Effect of sonication on European and Peruvian lupin flours: impact on the technological quality of gluten‐free breads and as a partial substitute for wheat

BACKGROUND: A widely cultivated pulse, lupin, has garnered interest for its beneficial nutritional properties, especially for baking applications. The harmful alkaloid content and poor functional properties of lupin limit its wider use. Sonication is an ecofriendly technology used to modify molecular structures. Thus, this study aimed to investigate whether sonication can improve the functional properties of Lupinus mutabilis (Peruvian) and L. angustifolius (European) flours for a better baking suitability in wheat and gluten-free breads. Both flours were sonicated and analyzed for their functional properties using Fourier transform infrared spectroscopy, water and oil absorption capacities, Mixolab, Rapid Visco Analyzer and texture profile analysis, and were then baked into bread formulations, substituting for wheat flour at 20% (w/w) and gluten-free flour at 10% (w/w). RESULTS: Sonicated L. angustifolius showed an increased water absorption capacity compared to the raw flour, improving the volume, texture, and moisture retention of gluten-free bread. Sonicated L. mutabilis showed deterioration in those same categories. In wheat formulations, lupin addition reduced product quality due to dilution of the gluten network. In gluten-free formulations, lupin addition - particularly sonicated L. angustifolius - improved texture parameters such as cohesiveness, springiness, and moisture retention. Sonication possibly unraveled protein aggregates and broke polysaccharide chains, forming a gluten-like network. Sonication affected starch gelatinization and retrogradation, thereby altering syneresis and shelf life. CONCLUSION: Sonication seems a promising tool for improving the functionality of blue lupin in gluten-free bread but is rather species-specific. A deeper understanding of protein-level structural changes induced by sonication is essential to expand its application across food matrices.