There are many kinds of sterilization treatment methods used in the field of food processing, which can be roughly divided into two types. The conventional heat sterilization method is indirect heat exchange using partition heat exchange, which will inevitably cause some side effects on the nutritional value, flavor and taste of food. The ohmic heating sterilization using high-frequency current is a new type of non-thermal sterilization technology. Its main principle is to use the electrical conductivity characteristics of food materials. Quickly generate heat to achieve uniform heating and sterilization in a short period of time. As a new type of food processing technology, ohmic heating is a process in which materials directly convert electrical energy into heat energy. It does not require the temperature difference between the surface and the interior of the object as the driving force for heat transfer, but generates heat within the entire volume of the material itself. , has the characteristics of fast heating speed, uniform heating, high energy utilization rate, and the obtained product has less loss of nutrients and high quality. In addition to thermal effects, the researchers also demonstrated that ohmic heating produces non-thermal effects, leading to polarization of charged macromolecules such as proteins and electroporation of cell membranes. This technology has been widely used in sterilization, inactivation of enzymes, dehydration, extraction and organic synthesis, and is receiving more and more attention. Based on this, the goal of this study is to design a set of ohmic heating sterilization devices that apply high-frequency current. The specific method is to use MATLAB to build a 20kW, 25kHz high-frequency power supply system, reduce harmonics and improve power factor through the power factor correction circuit, and use the phase-shift PWM inverter circuit to real-time based on the flow rate, inflow temperature and outflow temperature of the heated food. Adjust output power and inverter frequency. The cavity used for heating food is designed through industrial design software such as SolidWorks while the power supply design is completed. The simulation results show that the power system can adjust the output power in real time according to the conductivity and temperature of different foods, so that the heated food can reach the temperature required for pasteurization without greatly affecting the flavor and taste.

Ohmic heating; Pasteurization; High frequency power system; High frequency induced current