Effect of Microwave Power and Time on Total Phenolic Contents and Antioxidant Characteristics of Microwave Assisted Extracts of Watermelon Rind Powder

Abstract

Watermelon is gaining importance as a functional food due to its therapeutic effect. The therapeutic effect of watermelon has been reported and has been attributed to antioxidant constitutes.The major component in watermelon rind is citrulline that has a strong antioxidant effect which protect body from free-radical damage.Objective:This study was conducted to investigate the effect of microwave powers (150 W, 300 W & 450 W) and time intervals (1,3 & 5 minutes) on total phenolic content (TPC) and total flavonoid content (TFC) and antioxidant characteristics i.e. DPPH and ferric reducing antioxidant potential (FRAP) of microwave assisted extracts of watermelon rind powder.Methods:The extracts collected after Microwave assisted extraction (MAE) of watermelon rind wereanalyzed for their antioxidant potential through different tests including total phenolic contents (TPC), total flavonoid content (TFC), DPPH assayand FRAP.Results:Microwave assisted extraction by using ethanol as a solvent at different microwave powers and various time intervals showed that total antioxidant potential was significantly higher at low microwave power such as TPC ranges obtained at 150W for 1, 3 & 5 minutes of time intervals show ranges (159.84, 160.04 & 169.71 mg GAE/100 g). While TFC ranges at 150W for time 1, 3 & 5 minutes were (21.31, 24.15 & 42.20 mg CEQ/100g) whereas DPPH ranges at 150W for time 1, 3 & 5 minutes were (53.14, 54.87 & 68.17 % ascorbic acid inhibition) and FRAP values at 150W for time 1, 3 & 5 minutes were (201.71, 221.50 & 326.43 mg FE/100g). While high microwave power 450W can result in disruption of some antioxidants at various time intervals.Conclusions:Watermelon rind is a rich source of many antioxidants andmicrowave assisted extraction technique should be implemented in the food and nutraceutical industries and microwave assisted extracts of watermelon rind should be utilize for the development of new functional food to combat many health related problems