High voltage pulse generator design with voltage control for pulse electric field (PEF) pasteurization

PEF is the newest non thermal technology for liquid and semi-solid food processing system. Based on previous researches, PEF has the advantage of maintaining better nutritional products, compared with the thermal system. PEF pasteurization requires a high voltage pulse generator that produces electrical shock. Some researches had been conducted to develop a generator circuit which has high efficiency and pulse wave that can be used in the PEF technology. The circuit of a high-voltage pulse generator can be designed either from Resistor-Capacitor (RC) circuits or Resistor-Inductor-Capacitor (RLC) circuits. The high-voltage pulse generator with high voltage transformer used in this paper will be controlled by microcontroller ATMEGA 8535. The paper also explores the design of a high-voltage pulse generator which is equipped with voltage regulation that can be set through the key pad. Constant high-voltage pulse frequency is applied and is controlled by ATMEGA 8535 microcontroller. Chamber is designed as a Tube-shaped chamber with a pasteurized apple juice capacity of 1.5 liters. The high voltage transformer used in this paper is a step-up transformer with a maximum output of 100KV. The designed equipment is expected to produce high voltage in range of 20KV to 100KV with an increase scale of 20KV. The examination result shows there was an error between the expected and the real output voltage from the device/equipment. The average error of this equipment is 5.41% and the smallest error on 60KV output voltage is 0%. This paper also carried out tests on the vitamins A and C content in apple juice to investigate the effectiveness of the designed equipment compared with thermal pasteurization. The content of vitamins A and C in apple juice resulted from PEF pasteurization is remain unchanged. This can be seen from the content of vitamin A. Before pasteurization, the content was about 0.5034μg/gr and after pasteurization treatment using PEF, the content lies between 0.3676 and 0.435μg/gr, while pasteurization thermal treatment cause the content become 0.23g/gr. In general, the PEF treatment will cause the content of vitamin A decrease although it is not significant. A significant decline emerged from apple juice which was pasteurized by heat. The heating process causes a degradation of vitamin A content. Meanwhile, for the content of vitamin C, it was about 0.5034μg/gr before pasteurization treatment and it lies between 11.25 - 18.95 mg/100ml after pasteurization treatment using PEF and thermal pasteurization is 4.00 mg/100ml.