EFFECT OF PROCESS PARAMETERS OF MICROWAVE ASSISTED EXTRACTION (MAE) ON NATURAL PRODUCT YIELD FROM ONION PEEL

Globally, more than 30 % of the onion peels arises at the retail and purchaser levels, of which the post-harvest and dealing out level wastages report for the major share. So, studies on the characterization of unutilized fractions of the onion peels specify their potential candidature for reprocessing. Maximum preservation of these phytochemicals during extraction requires optimised process parameter conditions. A microwave-assisted extraction (MAE) method was considered for extraction of total phenolics, total flavonoids and DPPH scavenging activity from onion peels. The total phenolic capacity (TPC), total flavonoids content (TFC) and antioxidant activity percentage of extracts at optimised MAE conditions. The influence of six main extraction parameters on the extraction was modelled by using a second-order regression equation. The optimal MAE conditions were 210W microwave power, 15min irradiation time and 40 mL/g solvent to material ratio. Under the MAE optimised conditions, the recovery of TPC was 94.34 mg gallic acid equivalent/g dry weight (DW), TFC was 45.61(mg/g) and free radical scavenging activity 92.25%.When bioactive phytochemicals extracted from onion skin using MAE compared with UAE and CSE, it was also observed that the yield values in MAE extracts were higher than the other two extracts.