Effects of Boiling and Roasting Treatments on the Content of Total Phenolics and Flavonoids and the Antioxidant Activity of Peanut (Arachis hypogaea L.) Pod Shells

Abstract

This study was conducted to investigate the effect of boiling and roasting treatments on the phenolic and flavonoid contents and antioxidant activity of pod shells of two Sudanese peanut cultivars, Sodari and Ghabiash. The samples were subjected to a boiling process (1:5 w/v; 20 g/100 mL) at 100 °C for 45 min and a roasting treatment at 180 °C for 30 min. Results revealed that both cultivars are rich in phenolic compounds with high antioxidant activity in their shell. The boiling and dry roasting treatments significantly (p < 0.05) enhanced the total phenolic content, total flavonoid content, and antioxidant activity of the peanut shell for both peanut cultivars. The shells of Ghabiash peanut cultivar exhibited higher bioactive properties than the shells of Sodari cultivar, in which these properties were highly improved by roasting and boiling treatments. In general, peanut shells can serve as an important underutilized by-product, particularly after roasting treatment, for potential applications in food formulations.