Optimization of Pulsed Electric Fields-Assisted Extraction of Polyphenols from Potato Peels Using Response Surface Methodology

In this work, optimal pulsed electric fields-assisted extraction conditions were selected in order to intensify the extractability of polyphenol compounds with high antioxidant activity from potato peels. Effectiveness of PEF as cell disintegration technique was confirmed using both impedance measurements and scanning electron microscopy (SEM). Solid-liquid extraction (SLE) for both untreated and PEF pre-treated potato peels was optimized to determine the most effective solvent concentration (0-100% ethanol in water) as well as extraction temperature (20-50 degrees C) and time (30-240 min) using response surface methodology. Total phenolic compounds (TPC) and antioxidant activity (DPPH) of the extracts were determined. Results showed that the application of PEF prior to SLE has the potential to reduce duration, temperature, and consumption of solvent to achieve the same recovery yield of phenolic compounds. Under optimized conditions (54% ethanol, 233 min, and 50 degrees C for SLE; 52% ethanol, 230 min, and 50 degrees C for PEF), the extracts obtained from PEF pre-treated samples showed higher total phenolics yield (10%) and antioxidant activity (9%) as compared to the control extraction. Finally, HPLC-DAD analysis revealed the major classes of the detected polyphenolic compounds as chlorogenic, caffeic, syringic, protocatechuic, and p-coumaric acids, and no significant degradation of individual polyphenols due to PEF application was observed.