How starch structure and physicochemical properties dictate the porridge quality of diverse japonica rice varieties.

Rice porridge is a widely consumed staple, yet how starch structure governs porridge quality remains unclear. Six representative japonica rice varieties were selected, among which Jijing 830 (JR2) produced porridge with a thick, smooth, cohesive texture and the highest sensory scores. Notably, JR2 starch had an amylose content of 12.33%, a median granule size (D50) of 5.98 μm, and a relative crystallinity of 33.05%, values intermediate among the six varieties. These structural characteristics balanced starch leaching with granule integrity, favoring rapid hydration while preventing structural collapse. Furthermore, JR2 starch's relatively high peak viscosity, low setback, and high proportion of bound water endowed the porridge with excellent water retention, forming a stable porridge matrix. Correlation analysis confirmed that starch composition, crystallinity, pasting behavior, and water distribution significantly influenced texture and sensory attributes of porridge. These findings reveal the structural basis of porridge palatability, guiding breeding and industrial utilization of japonica rice.