Comparative characterization of pectin fractions from pomegranate peel: Structure–Function relationships

This study evaluated structure-function relationships of four pectin derived from pomegranate peel: alcohol-insoluble residue (AIR), water-soluble pectin (WSP), homogalacturonan (HG)-enriched pectin, and rhamnogalacturonan-I (RG-I)-enriched pectin. AIR and WSP exhibited higher molecular weight ( M w ) and moderate degree of methylation/acetylation (DM/DA), showing superior water- and oil-holding capacities (13.88–20.90 g/g and 4.14–4.65 g/g respectively), excellent emulsifying activity index and emulsion stability index (EAI: 12–16 m 2 /g, ESI: 80–91%), and strong antioxidant activity. HG-enriched pectin, rich in galacturonic acid (GalA) (74.24–89.94%) and low DM (<5%), formed strong calcium-induced gels (gel strength up to 190 g) but had limited emulsifying and holding capacities. RG-I-enriched pectin, with abundant neutral sugar branches, demonstrated moderate overall functionality. Structure-function correlation analysis revealed that high M w , moderate DM/DA, and branching enhanced emulsifying, water-holding, oil-holding, and antioxidant properties, while linear HG structures promoted gel formation. These results support the targeted use of pomegranate peel pectin fractions as functional ingredients in food applications. • High DM and DA improved emulsification but weaken the gel-forming ability. • High DA and branching enhance the antioxidant capacity of pectin significantly. • AIR and WSP showed strong emulsification, WHC, OHC and antioxidant properties. • HG-enriched pectin exhibited gel strength in calcium-induced systems. • Pectin functional depended on Mw, DM, DA, MR3 and GalA content.