Optimization of Bioactive Components Extraction from Onion by-products by Microwave-Assisted Using Response Surface Method (RSM)

Microwave- assisted extraction is efficiency technic for extraction bioactive compounds and valuable in biological compounds that lead to accelerating the food heat processing, better extraction and quality, time decreasing and amount of solvent without decomposition of heat sensitive compounds that is applicable in both laboratory and industrial scales. The aim of this study, optimization of extraction was using response surface method and Face-center design, in order to investigate the effect of time (60-120 Sec), power (300-700 W) and ethanol percentage (40–80 %) on the yield of polyphenol, , and also the antioxidant activity and optimization of extraction process. The results showed that, model fitting was suitable. The phenolic content was decreased by increasing the ethanol concentration, significantly. Simultaneous increase of extraction time and power, resulted in significant increase of total phenolic, contents (P<0.05). Maximum yield of antioxidant compounds is achieved with extraction time of 120 sec, extraction power of 300 W and ethanol percentage of 80%. Under these conditions, the values have been assayed: 25.37(mg/100 g) for quercetin, 53.60% for DPPH free radical scavenging activity, extraction efficiency, 77.76%, and 47.43 (mg/kG) for total polyphenol and 416.79 (µm/g) for ferric ion reducing antioxidant power. As a result, Microwave assisted extraction method by two friendly environment solvent (water and ethanol) in different concentrations for extraction of bioactive compounds and antioxidant of onion by-products can used at a shorter extraction time and energy saving.