Extraction of phenolic compounds from basil (Ocimum americanum L.) leaves with pretreatment using pulsed electric field (PEF)

The study was conducted to determine the role of the pulsed electric field (PEF) as a pretreatment on the extraction of phenolic compounds from basil (Ocimum americanum, L.) leaves. The research used Randomized Block Design (RBD) with two factors, factor 1: exposure time (10, 15, and 20 seconds) and factor 2: voltage (1000, 1500, and 2000 Volts). Extraction was done by maceration using 80% ethanol at 50°C. The results showed that PEF treatment had a significant effect on total phenolic compounds (TPC) and antioxidant activity (IC₅₀) of basil extract. The best treatment at exposure time of 10 seconds and a voltage of 1500 Volts obtains TPC of 260.50 mg GAE/g and IC₅₀ of 35.96 ppm. Whereas the untreated sample (without PEF pre-treatment) obtains TPC of 175.75 mg GAE/g and IC₅₀ of 116.25 ppm. The data showed that PEF treatment before the extraction of basil leaves increased TPC by 1.5 times and antioxidant activity by 3.2 times. FTIR spectra showed that PEF pre-treatment increases absorption or decreases transmittance, which indicates the increase of extract concentration. Scanning electron microscopy (SEM) imaging showed that PEF treatment causes pore formation on the cell membrane, which might facilitate the release of phenolic compounds.