Structural characteristics, functional properties, antioxidant and hypoglycemic activities of pectins from feijoa (Acca sellowiana) peel.

The structure characteristics, functional properties, antioxidant and hypoglycemic activities of pectins extracted from feijoa peel with water (FP-W), acid (FP-A) and alkali (FP-B) were investigated. Results showed that the feijoa peel pectins (FPs) were mainly composed of galacturonic acid, arabinose, galactose and rhamnose. FP-W and FP-A had higher proportion of homogalacturonan domain, degree of esterification and molecular weight (for main component) than FP-B; FP-B owned the highest yield, protein and polyphenol contents. FP-W had a compact and smooth surface morphology unlike FP-A and FP-B. FP-W and FP-A had better thermal stability than FP-B. The rheological analysis suggested that the FPs exhibited pseudoplastic fluid behavior, and the elastic characteristics were dominant. Results showed that FP-W and FP-B had superior antioxidant and hypoglycemic activities than FP-A. According to correlation analysis, monosaccharide composition, sugar ratios and degree of acetylation were chief factors affecting the functional properties, antioxidant and hypoglycemic activities of the FPs.