Effect of heat treatment on phenolic content and antioxidant activity of peanut (Arachis hypogaea L.) extracts

Peanuts are rich in various bioactive compounds, including total phenolics and total flavonoids. The aim of this study is to evaluate the effects of heating on total phenolic content, total flavonoid content, and antioxidant activity in peanut (Arachis hypogaea L). Seven peanut treatments were prepared, including heated peanuts at 95 °C for 30, 35, 40, and 45 min, and three unheated forms (unheated whole peanut, inner shell peanut, and outer shell peanut). Changes in antioxidant activity in heated peanuts were assessed by determining total phenolics, total flavonoids, and antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reduction activity potential (FRAP), and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assays. These values were compared with those of unheated peanuts. The results showed that peanut extract heated at 95 °C for 30 min, and the inner shell of peanuts, contained the highest concentrations of phenolic and flavonoid components (22.33, 24.50 mg GAE/g and 5.23, 6.61 mg QE/g, respectively). The highest DPPH, ABTS, and FRAP scavenging activities were also observed in the peanut extract heated at 95 °C for 30 min and in the inner shell peanut extract.