Molecular interaction of β-carotene with sweet potato starch: A bleaching-restitution assay

This work aimed to investigate the most plausible molecular interactions between beta-carotene (beta Cat) and orange-fleshed sweet potato (OFSP) starch, by using a bleaching-restitution strategy. OFSP's raw flour (RF) was partially (TF) and extensively (starch) bleached with a graded polarity solvent system. The in vitro interaction (saturated restitution) of pure beta Cat to starch (beta Cat + S) at 2.5, 5, 10 g.100 g(-1) was tracked by FE-SEM, ATR-FTIR, XRD and changes in starch digestibility [slow (SDS), rapid (RDS), and resistant (RS)] were documented. beta Cat + S interaction occurs mostly by H+ bonding (inter and intra-helical) and CH-pi stacking (alkene chains - glucose rings), altering starch's molecular order and crystallinity, RS: SDS ratio and increasing intra/inter type-V inclusion and non-inclusion complexes, in a dose-dependent manner. Data suggests that beta Cat + S is governed by non-covalent forces promoting starch's resistance to digestion, probably influencing the bioaccessibility and bioavailability of both beta Cat and glucose monomers.