Sterilization of liquid by high electric field pulse

There are two methods for sterilization of foods, heating and non-heating. The heating sterilization is now widely used for liquid food such as milk and juice. However this method has some problems. One of them is the changes in nutrition and quality of food caused by heating up to temperature for example 63°C to kill bacteria. The large energy consumption is also a drawback of heating sterilization; the heating sterilization needs to heat up whole volume of liquid. The non-heating sterilization such as UV irradiation, ion beam irradiation, and chemical methods are proposed to avoid these problems of heating method. The pulse sterilization, one of the non-heating methods, attracts attentions because it causes little change in nutrition of liquid food, and low energy consumption. We have studied the sterilization of liquid using high electric field pulse. Sample was liquid medium including Escherichia coli. E. coli was used because of easy cultivation. We used nonpoisonous K coli. We applied high voltage pulse to a coaxial cylindrical tank containing sample liquid. After application of 50 pulses, the survival rate of K coli was reduced to 0.01%. This value of 0.01% is far superior to 1%, which is reported for milk sterilized at 63°C for 30 minutes.