Understanding the application-related properties of ultrashort-duration varieties rice starch in different planting...

This study investigated the physicochemical properties and digestive properties of rice starch isolated from four ultrashort-duration varieties (CPPC16, CPPC18, CPPC38 and CPPC52) grown in the early (April) and late (July) seasons, respectively. It was found that planting season was confirmed to significantly influence the properties of starch in duration varieties rice. Possessing higher apparent amylose content (AAC) in rice grown during early seasons contributed to the aggregation of amylose and recrystallization of amylopectin, resulting in an increase in retrogradation value (Δη_sb), pasting temperature (T_ps), and conferring higher G' to the starch gels. The larger granule size provides starch gels with higher water retention and viscoelasticity. In addition, synergistic effects of AAC, granule size, and molecular ordering (short-range) on digestion rates (k) were observed, the effect of a single factor was not determinative of the digestion rates. E18 and E38 starches exhibit elevated AAC (24.70 %, 25.36 %), enhanced structural order, and larger granule sizes (7.25 microm, 7.10 microm). These properties collectively impede enzyme diffusion and penetration into the starch matrix, reduce enzyme-substrate binding efficiency, suppress k (3.04 × 10^-3 min^-1, 3.13 × 10^-3 min^-1), and elevate resistant starch (RS) levels (72.66 %,73.96 %), demonstrating significant potential for low glycemic index food design. Meanwhile, the lower Δη_sb (1219 cP) and T_ps (78.28 °C) of L52 starch may have potential for application in the development of easy-to-swallow foods.