Cultivar-dependent Variations in Pigmented Brown Rice Flours Determine Rice Cake Quality: Key Role of Amylose in Structure Formation

Pigmented brown rice flour (PBRF) is a promising functional ingredient, yet the links between flour traits and product quality remain unclear. Here, five PBRFs differing in pericarp color and amylose content were characterized and used for rice cake production. Amylose content strongly contributed to variations in starch functionality and rice cake quality within the whole PBRFs matrix. High amylose rice flours tended to show restricted hydration, higher pasting temperature, and stronger cooling-stage viscosity recovery, producing rice cakes with denser microstructures, distinct water-related proton mobility, higher hardness, and lower springiness. In contrast, waxy rice flours tended to produce more porous and elastic cakes. Darker cultivars showed higher soluble phenolic contents and stronger antioxidant capacities, with B-F showing the highest antioxidant potential. B-C had the highest trained-panel acceptability, whereas Y-C showed the strongest aroma response. This study links cultivar differences, especially amylose-related starch behavior, to rice cake quality and supports the targeted utilization of pigmented brown rice.