Heat-treated Bean Flour: Exploring Techno-Functionality Via Starch-Protein Structure-Function Analysis

The study aimed to modify the structure of two major components ( i.e. , starch and protein) in bean flour to enhance bean flour's techno-functionality. The bean flour was processed by two very different temperature treatments - dry heat (DH) and extrusion. The effect of processing on starch and protein was analyzed by characterizing their physicochemical properties. While processing did not alter, as expected, the total starch (35-47 % (db)) and protein (24-25 % (db)) content of the bean flours, it did significantly change the microstructure and molecular architecture of starch and proteins. DH processing mainly affected protein conformation while minimally affecting starch structure. Conversely, extrusion caused extensive structural modifications of both starch and protein in bean flour. Both DH and extrusion processing decreased intramolecular beta-sheet secondary structure of bean protein. Additionally, both unprocessed and thermally processed bean flours were characterized for their techno-functional properties. The heat treatments (DH and extrusion) did not only result in colour variations, but they also modified the particle size distribution, pasting profile, rheological properties, and water absorption and solubility indices of the bean flour. The structure-function relationship of bean flour components (starch and protein) and bean flour's functionality implied that thermal processing treatments led to changes in the protein/starch matrix which were reflected in the techno-functionality of processed bean flours. However, the changes induced by each of the different types of processing were very different, thus, unlocking different opportunities for functionalization of bean flours for food manufacturing and product development applications.