Development Of A New High Voltage Pulsed Electric Field Sterilization Apparatus

The tradition method of sterilization is thermal processing, it brings great damages to the nutrition, color and taste of foods. At present, many different non-thermal processing technology has been used in international, such as infrared ray sterilization, ultrasonic sterilization, radiate sterilization and pulsed intensity light. As a newly-developed non-thermal Sterilization method, high voltage pulsed electric field (HPEF) has the characteristic of short time, high effective, low temperature rise and keeping the nutrition of the food effectually, In recently years, PEF has become the most hot spot in the field of non-thermal food processing. And it is one of the sterilization methods which have promising future in industrialization.Bovine colostrums have the high nutritional value and unique physiological function. Immunoglobulin is the most arresting immune factor in bovine colostrums, And it can improve body immunity. But the Immunoglobulin will be serious thermal denatured if its temperature is over 75℃. So the quality of the products will be affected by the method of food sterilization, In our country, the bovine colostrums is processed by radicidation and lyophilization to produce simple bovine colostrums products. The purity of immunoglobulin is low and it can only be added to common food. All of these decrease immunoglobulin's value.Referencing to the information at home and abroad, a PEF sterilization system is developed. The following work has been carried out:Firstly, the development of sterilization by PEF is summarized ; the deactivation mechanisms of microorganisms in the pulsed electric field are introduced in detail; the model of microbial inactivation is summarized; and the key factors of sterilization effects are represented.Secondly, the equipment of PEF is designed utilizing High-voltage testing technology, power electronics and modern control techniques. Various treatment chambers were designed and the distributions of electric field in these chambers were acquired by Ansys9.0.At last, bovine colostrums sterilization experiments were carried out by applying PEF. And the sterilization effects were analyzed and compared in basis of electric intensity, pulse number and temperature rise. It proved that the effect of electric intensity on inactive ratio is more distinctive than it of pulses number, in the range of the thermal technology, the better sterilization effect is acquired by increasing temperature. Research demonstrates that the developed apparatus has a better sterilization effect than conventional ones.