The effect of combination methods of high voltage electric field treatments and ultrasonic on extraction efficiency and physicochemical properties of oak kernel oil
摘要
In the present study, the extraction efficiency (EE) of oak kernel oil was individually evaluated using high-voltage electric field (HVEF) with voltages of 3.5, 7, and 10.5 kV/cm at different time (30, 45, and 60 min) and ultrasound (US) with a power of 300 W at times of 2.5–45 min. The combination of HVEF (voltage of 10.5 kV) and US (power of 300 W) at times of 2.5, 5, 15, and 45 min was then applied to compare the EE and energy consumption with cold extraction as a conventional assay. The combination treatment significantly increased the EE up to 1.2 times compared to cold extraction. The extracted oil through combination method illustrated remarkable higher peroxide value, unsaponifiable matter, brightness and lower iodine value than the conventional method. The combination had no significant effect on other physicochemical properties, including specific gravity (SG), refractive index (RI), saponification value, and a* index of extracted oil. Regarding energy consumption, the combined method required about 7.61 kJ, while cold extraction demanded higher energy up to 508 kJ. Therefore, this study suggested that a combination of new technologies could be a promising approach to increase EE in less time, with lower energy consumption compared to the conventional extraction method.