Optimization extraction, characterization and antioxidant activities of pectic polysaccharide from tangerine peels

Response surface methodology (RSM) was employed to optimize the microwave-assisted extraction (MAE) process of pectic polysaccharide (TPPs) from tangerines peel. The optimal extraction conditions were as follows: microwave power 704W, extraction temperature 52.2 degrees C, and extraction time 41.8 min Under these conditions, the experimental yield was 19.9 +/- 0.2%. The purified pectic polysaccharide TPP5-2-1 was successfully obtained by anion-exchange and gel filtration chromatography. TPP5-2-1, linked mainly by alpha-glycosidic bonds, consisted of galacturonic acid (GalA), arabinose (Ara), galactose (Gal), rhamnose (Rha), glucose (Glc) and mannose (Man) with the average molecular weight of 17.8 kDa, and had typical IR spectra characteristic of pectic polysaccharides. Antioxidant activities were investigated on the basis of ferric-reducing antioxidant power (FRAP), hydroxyl radical ("OH), 1,1-dipheny1-2-picrylhydrazyl radical (DPPH center dot) and superoxide radical (O-center dot(2)-) scavenging assay. TPP5-2-1 exhibited significant antioxidant activity in a concentration-dependent manner and might be exploited as effective natural antioxidant applied in functional food and medicine. (C) 2015 Elsevier Ltd. All rights reserved.