Characterization and encapsulation properties of pectic polysaccharides derived from Choerospondias axillaris fruit

The fruit of Choerospondias axillaris is commonly used in the food industry for producing candies and cakes. However, limited research on polysaccharides from C. axillaris fruit has restricted their application. In this study, a homogeneous pectic polysaccharide of 22.4 kDa, designated as CAP-3, was isolated from C. axillaris fruit. Structural characterization revealed that CAP-3 exhibited a backbone composed of consecutive 1,4-α-GalpA residues and alternating disaccharide units of 1,2-α-Rhap and 1,4-α-GalpA, with DM of 8.4% and DA of 0.05%. The side chains consisted of 1,6-β-Galp and 1,5-α-Araf linked to C-3 of GalpA, as well as T-β-Galp and T-α-GalpA residues attached to C-4 of Rha. To explore its application potential, the encapsulation performance of CAP-3 was evaluated using two representative food bioactives, resveratrol and astragaloside IV, as model compounds. Accordingly, RES@CAP-3-Mg²⁺ (RES:CAP-3, 1: 4, w/w) and AS-IV@CAP-3-zein (AS-IV:zein:CAP-3, 1: 10: 5, w/w/w) complexes were successfully constructed via different assembly mechanisms. Both complexes exhibited favorable physicochemical properties, including uniform particle size distributions (369.6 nm and 397.6 nm), spherical morphology, spectral features, and improved stability. These findings demonstrated that CAP-3 is a potential natural pectin-based delivery medium for encapsulating functional ingredients, thereby expanding the applications of C. axillaris in the food field.