Amylopectin chain length distribution shows limited explanatory power for cooked rice digestibility: A comparative analysis using SEC-DRI-MALS, FACE, and HPAEC

In this study, 28 rice starches with varying amylose contents ranging between 0.64 % ~ 41.19 % were analyzed using size-exclusion chromatography (SEC), fluorophore-assisted carbohydrate electrophoresis (FACE), and high-performance anion-exchange chromatography (HPAEC). All methods reproduced canonical multi-modal chain length distribution (CLD) but differed in reliability: SEC was limited by band broadening, HPAEC resolved medium chains but became noisy at very high degree of polymerization above ~68. In contrast, FACE combined high resolution of short and long chains with mild processing, providing the most robust and reproducible profiles, which is further confirmed by the analysis of compact, short-chain-rich topologies in low-amylose starches. Importantly, no statistically significant correlations were detected between FACE-derived CLD parameters and the in vitro digestion parameters of freshly cooked rice under the present sample size, highlighting the need for integrated approaches to link starch molecular structure with functional properties.