Effects of extraction factors and spray drying on flavonoid content and antioxidant property of extracts from Pomelo peel

Abstract

The aim of this study was to find out the appropriate conditions for the ethanolic decoction extraction process of total flavonoid contents (TFC) extracted from pomelo peels, including ethanol concentration, sample to solvent ratio (g:ml), extracting time (minutes), extracting temperature (oC). Furthermore, the effect of spray-drying on TFC and total antioxidant capacity (TAC) of pomelo peel also be examined. Three commercially available pomelo spp. growing in different region of Viet Nam (the South, West and Middle region) were used in this study. The results showed that that aqueous ethanol (80%), sample:solvent ratio 1:30, extracting time 30 minutes, extracting temperature of 45oC, were the best conditions for the extraction of TFC from pomelo peels. The TFC ranged from 3.52±0.09 (mg quercetin equivalent (QE)/g dry basis peel weight) to 4.29±0.08 (mgQE/g dry basis peel weight). The total flavonoid content of Tan Trieu flavonoid peel was the highest, followed by Nam Roi of 4.13±0.08 (mgQE/g dry basis peel weight) and Thanh Tra of 3.52±0.08 (mgQE/g dry basis peel weight). It was shown that, the flavonoid contents decreased significantly from 4.10±0.04 (mgQE/g dry basis) to 0.36±0.01 (mgQE/g dry basis) and antioxidant capacity (DPPH radical scavenging activity) also decreased after spray-drying, which was from 49.99±0.16% to 11.72±0.09% DPPH scavenging. Keyword: pomelo peel, flavonoid, antioxidant capacity, extraction, Vietnamese Citrus