An antioxidative potential-based comparison of different peanut extraction methods, optimized through response surface methodology

In this research, response surface methodology was employed in order to find the most efficient conditions to produce peanut extracts with the highest antioxidative potential (by DPPH, ABTS, FRAP, and ORAC tests) from ultrasound-assisted (UAE) and microwave-assisted (MAE) extractions. The optimal conditions for UAE were 75 ml of 30%v/v ethanol as extraction solvent, extraction temperature of 65°C, and 180 min extraction time. Optimal conditions for MAE were 15 ml of 30%v/v ethanol as extraction solvent, extraction temperature of 80°C, and 90 s extraction time. The generated models presented a reliable antioxidative response by showing non-difference between experimental and predicted values within a 95% confidence level. Characteristics such as antioxidant activities, TPC, resveratrol, and TFC were used to compare the effectiveness of the obtained extracts and the SLE extract from our previous work. The UAE extract displayed higher extraction efficiency than that of MAE in terms of higher levels of all responses (p < 0.05). Slightly lower antioxidant values of MAE might be due to the limited solvent volume used, which was five times less than that of UAE. Moreover, the high efficacy of MAE was confirmed by its extraction time, which was 120 times shorter than that of UAE. Ultimately, the correlation analysis implied that the antioxidant activity of peanut extracts was contributed by TPC rather than resveratrol or TFC, and the revealed TPC in this study was higher than previous reports.