Optimization of the pulsed electric field-assisted extraction of functional compounds from Nepeta binaludensis.

Pulsed electric field (PEF) treatment was used for extracting effective components from Nepeta (Nepeta binaludensis Jamzad). A response surface method was used to investigate the effects of independent process variables (voltage of pulsed electric field (VPEF): 2, 4 and 6 kV cm-1 and number of pulsed electric field (NPEF): 20, 40 and 60 n) on the yield (Y) and antioxidant characteristics: total phenolic compounds (TPC), 1,1- diphenyl -2- picrylhydrazyl free radical scavenging (DPPHsc), ferric reducing-antioxidant power (FRAP), half maximal of radical-scavenging activity (IC50) of Nepeta extract (aerial parts). According to Derringer's desired function approach, the optimal conditions based on both individual and combinations of all process variables were VPEF 6 kV cm-1 and NPEF 60 n. At this optimum condition, the Y, TPC, DPPHSC, FRAP, and IC50 of the extract were found to be 11.36%, 417.85 mg GA g-1, 74.8%, 1688.53 µmol Fe2+ g-1, and 0.32 mg mL-1, respectively. The experimental values were in a good agreement with the predicted values. Also, the extract at optimal conditions of PEF (PEFopt-x) had a higher quantity of chlorogenic acid, caffeic acid, rutin, para-coumaric acid, rosemarinic acid, kaempferol, and apigenin compared with solvent extract. The addition of PEFopt-x to the purified soybean oil at the levels of 6% increased oxidative stability index (2.65 h) close to butylated hydroxy toluene (2.78 h). [ABSTRACT FROM AUTHOR]