Design and Analysis of an SME-Level Pulsed Electric Field Device for Extracting Bioactive Compounds from Black Rice

Design and Analysis of SME-Pulsed Electric Field for The Extraction of Bioactive Compounds form Purple Rice

Abstract

This research developed a small-scale Pulsed Electric Field (PEF) machine to extract bioactive compounds from black rice grown in Doi Saket and assessed its extraction efficiency. The primary voltage ranged from 0 to 220 V, with secondary high voltage AC and DC outputs spanning from 0.68 to 15.00 kV and 0.96 to 21.21 kV, respectively. The experiment used a ratio of 1 kg of black rice to 2 L of water, with electric field strengths of 4, 5, and 6 kV/cm at a frequency of 1 Hz, varying the number of pulses between 1,000, 3,000, and 5,000. Results showed that 6 kV/cm and 5,000 pulses yielded the highest anthocyanin content (3.23±0.04 mg/L), which significantly differed from other conditions (p<0.05). The highest antioxidant levels were observed at 4 kV/cm for 1,000 pulses and 5 kV/cm for 1,000 pulses (77.86±0.67% and 76.91±0.71%, respectively), though these levels decreased in comparison to traditional extraction, showing statistical significance (p<0.05). However, a higher pulse count led to an increase in anthocyanin content. Furthermore, increased electric field intensity raised antioxidant yields, though this effect plateaued beyond a certain point. Optimal extraction conditions were achieved at 5 kV/cm and 3,000 pulses, yielding anthocyanin and antioxidant contents of 1.02±0.04 mg/L and 59.72±0.34%, respectively. The extraction process was most effective when temperatures remained below 50°C (without a cooling system) and pressure was kept at 1 atm. Additionally, the study developed a PEF prototype for bioactive compound extraction from black rice.