Comparative analysis of pectic polysaccharides isolated from various thinned young red-fleshed kiwifruits: Structural properties and biological functions

To utilize thinned young kiwifruit for potential industrial applications, this study compared structural properties and in vitro bioactivities of pectic polysaccharides isolated from three thinned young red-fleshed kiwifruit cultivars, including Actinidia chinensis cv. 'Donghong', 'Hongshi', and 'Hongyang'. The results demonstrated that these young kiwifruit byproducts were rich in pectic polysaccharides, with extraction yields of 90.7-101.3 mg/g dry weight. Although their bound polyphenols (8.02-8.93 mg GAE/100 mg), esterification degrees (50.45-61.32 %), and molecular weights (7.44 × 10⁴-8.51 × 10⁴ Da) varied across cultivars, the glycosidic linkage patterns showed remarkable consistency, dominated by homogalacturonan (12.07-13.84 mol%) and rhamnogalacturonan-I (70.25-75.09 mol%) regions. Notably, all these pectic polysaccharides, particularly those isolated from the 'Donghong' cultivar, demonstrated notable antioxidant, antiglycation, prebiotic, and immunoenhancing activities in vitro. These findings indicate that thinned red-fleshed kiwifruit byproducts are rich sources of RG-I enriched pectic polysaccharides, with significant potential as functional food ingredients.