Optimization of phenolic compounds recovery and in vitro antioxidant activity of Algerian eggplant (Solanum melongena L.)

Abstract

The optimum conditions for extraction of total phenolic contents (TPC) and maintaining the highest antioxidant activity from eggplant were determined. Extraction experiments were carried out by investigating the effects of the solvent nature (acetone, ethanol, methanol, or water), solvent concentration (30-90%), extraction temperature (30-100°C), extraction time (30-120 min), solid to solvent ratio (1/25-1/100 g/mL), and number of extractions (1, 2 and 3) on the recovery of phenolic compounds and antioxidant activity of the extracts. The TPC was assessed to determine the polyphenolic component while free radical scavenging activity (FRSA) and ferric-reducing power (FRP) were used to evaluate the antioxidant activity of eggplant extracts. All extraction parameters had significant effects (p<0.05) on the TPC extraction and the antioxidant activities. The best conditions were obtained using three extraction steps with aqueous acetone 70% (v/v) at 25°C for 60 min and with 1 g/50 mL solid to solvent ratio. The optimum extraction conditions exhibit the TPC concentrations of 794.94 mg GAE/100 g and antioxidant activities of 737.86 mg TE/g (FRSA) and 28.00 mg TE/g (FRP). The free radical scavenging and ferric-reducing potentials were found to be positively significantly correlated with phenolic content under the influence of all extraction parameters.