Comparative study of low-voltage electric field-induced, ultrasound-assisted and maceration extraction of phenolic acids.

This study designed to conduction an investigation into the effect of low-voltage electric field (EF) on the phenolic acids extraction from plant materials. In this regards, Nepeta racemosa was selected to study as a source of phenolic acids. The EF extracted phenolic acids amounts were compared with ultrasound-assisted and maceration extractions. Suitable extraction condition was optimized for ultrasound-assisted extraction. The EF method was optimized for voltage (40, 50 and 60 V) and electrodes gap (1, 1.5, 2 and 2.5 cm). Phenolic acid amounts and antioxidant activity of extracts were investigated by HPLC and DPPH radical methods, respectively. The optimal condition for EF method extraction of total studied phenolic acids amount was obtained 2.5 cm of electrodes gap and 40 V for applied voltage. The results showed a considerable increasing in total phenolic acid amounts and antioxidant activity for EF comparison with other methods. Total phenolic acid amount and antioxidant activity of maceration, ultrasound-assisted and EF extraction methods were obtained as 3.58, 7.57, 19.88 mg/g dw of plant and IC50 values of 110.77, 81.44, 43.74 μg/mL, respectively. Based on obtained results, EF extraction method caused to increase of phenolic acids amounts 3-4 times and antioxidant activity 2-3 times rather that other methods. The findings for Nepeta racemosa extract suggest application of electric field extraction method for food and industrial purposes because of increasing bioactive compounds recovery and decreasing of time and cost.