Extraction of pectin from jelly fig shell using microwave heating extraction: pectin physicochemical properties and antioxidant activities

Abstract

Abstract Jelly fig is a crop of high economic value; however, the processing by-product of jelly fig, “jelly fig shell”, is not well utilized. In this study, jelly fig shell pectin was extracted through the microwave extraction technique. Then, galacturonic acid content, degree of esterification, molecular weight, functional group properties, and antioxidant activity were determined. The highest pectin yield (21.6 ± 0.1 %) was obtained at 200 mM citric acid and microwave power of 800 W, with extraction time of 4 min. The content of galacturonic acid in pectin was greater than 65 %, which meets the specifications of food-grade pectin. In terms of antioxidant ability, the IC50 of 2,2-diphenylpicrylhydrazyl (DPPH) free radical scavenging rate of jelly fig shell pectin was 175.1 μg/mL. These results suggest that, comparing to the extracted jelly fig seed pectin, jelly fig shell has stable quality under more desirable extraction conditions, and has better physicochemical properties.