Pasting and gelation of faba bean starch-protein mixtures

Starch and protein are major components in many foods, contributing to nutritional and textural properties. Understanding how the behaviour and interactions of these components contribute to different textures is important. In this study, mixed gel systems were created with different ratios of starch to protein (constant solid content 12%) extracted from faba bean, a promising crop for locally produced plant-based foods in cold climate regions. The mixed starch-protein gels were characterised in terms of pasting, texture and microstructure. Starch-rich mixtures showed higher water binding and water absorption than samples with higher protein content. A tendency for more efficient hydration in starch-rich samples was confirmed by NMR. Iodine affinity appeared to be lower for high-protein samples, particularly at higher temperatures. Mixtures with high starch content also showed higher viscosity during pasting, higher storage modulus throughout gelation, lower tan delta and lower frequency dependence of the final gel. Characterisation by compression tests showed stronger and more elastic gels with increasing starch content. Light microscopy revealed that starch granules were tightly packed, espe-cially at higher starch content, with protein filling the spaces between starch granules. SEM micrographs revealed a network structure with larger pores and thicker strands in samples with higher starch content. Overall, increasing protein content reduced viscosity during pasting and caused softer gels, likely owing to different gelation and hydration properties of starch and protein.