Incorporation of Germinated Lupin into Corn-Based Extrudates: Focus on Starch Digestibility, Matrix Structure and Physicochemical Properties

The research aimed to assess the effects of incorporating germinated Lupinus angustifolius flour into corn extrudates for different periods (3, 5, and 7 days), focusing on starch digestibility, morphological structure, thermal, and pasting properties. Extrudate with germinated lupinus flour for 7 days (EG7) significantly increased the content of slowly digestible starch up to 10.56% (p < 0.05). Crystallinity increased up to 20% in extrudates with germinated flour compared to extrudates with ungerminated flour (EUG), observing changes at the molecular level by FTIR that impact the thermal and pasting properties. X-ray diffraction revealed angles of 2θ = 11.31, 16.60, 19.91, and 33.04 as a result of the germination and extrusion processes. Microstructural analysis indicated starch-protein interactions influencing changes in calorimetry, viscosity, X-ray diffraction, and digestibility. PCA allowed establishing that the addition of germinated flours significantly affected the properties and microstructural characteristics of extruded products, potentially affecting digestibility and nutritional quality.