Influence of extraction methods on navel orange peel pectin: structural characteristics, antioxidant activity and cytoprotective capacity

Summary To make high‐value utilisation of citrus peel waste, three simple extraction techniques (acidic, alkaline and hydrothermal methods) were used to prepare pectins from navel orange peel. The influence of different methods on the structure and antioxidant capacities of all pectin preparations was investigated and compared. All findings revealed that the yield, degree of esterification, molecular weight, monosaccharide composition and antioxidant activities of all samples were significantly different. Alkali‐extracted pectin exhibited highest yield (22.6%), acid‐extracted pectin belonged to high‐ester pectin and hydrothermal‐extracted pectin had lowest molecular weight (109.2 kDa). Interestingly, due to the superior proportion of side‐chain structure, alkali‐extracted pectin possessed a better ability to scavenge free radicals than other samples. More importantly, alkali‐extracted pectin could protect macrophages from H 2 O 2 ‐induced oxidative damage by enhancing SOD activity and reducing MDA levels. All results contributed to our knowledge of the association among extraction techniques, structural characteristics and resultant bioactivities for pectic polysaccharides.