A short-chain debranched starch-based self-assembled delivery system for β-carotene: Multi-scale structure, controlled release, and bioavailability enhancement.

A hierarchical self-assembled delivery system for β-carotene was developed using short-chain debranched starch, β-cyclodextrin, and chitosan. The effects of starch multi-scale structure, regulated by enzymatic debranching for 12, 24, or 36 h, on encapsulation efficiency, in vitro release, and ABTS radical scavenging was systematically investigated. β-Carotene was first incorporated into β-cyclodextrin to form an inclusion complex with an encapsulation efficiency of 52.39 μg/mg. Subsequent co-assembly with short-chain debranched starch and chitosan produced β-carotene-loaded particles with hydrodynamic diameters of 3.20-3.61 μm, high encapsulation efficiencies of 84.68-92.73% (w/w), and loading capacities of 7.03-7.81 mg/g. β-CC-S36 exhibited the highest encapsulation efficiency of 92.73% (w/w), representing a 9.5% increase compared with β-CC-S12. In contrast, the formulation prepared with starch debranched for 24 h (β-CC-S24) exhibited the most favorable sustained release performance which was associated with the highest crystallinity of S24 (39.93%). This ordered structure reduced premature gastric release and supported sustained intestinal release, with 85.90% (w/w) of β-carotene released after 6 h in the simulated intestinal phase and 1.07 mg β-carotene/g particles still retained. These release kinetics reduced burst release and rapid local accumulation of β-carotene, which may favor intestinal availability and subsequent conversion to vitamin A. This study highlights the importance of starch multi-scale structural regulation in designing carbohydrate-based carriers for the delivery of hydrophobic bioactive compounds in functional foods.