This paper introduces the findings obtained from the development of pasteurization technologies using high voltage pulse electric field (PEF) technology and atmospheric non-equilibrium plasma technology, as engineering applications of high-voltage technology in the food field. In the pasteurization of liquid foods using PEF, we developed and examined the characteristics of a device that incorporates carbon electrodes to prevent metal elution from the electrodes, a membrane structure to prevent the treatment solution from contacting the high-voltage electrodes, and a cooling system for the treatment solution. Using this device, we achieved low-temperature sterilization of sake yeast and Lactobacillus homohiochii in sake. Additionally, we investigated the sensitivity of microorganisms to PEF, the stress responses induced by PEF, and factors affecting sublethally injured cells. In the pasteurization of solid foods using atmospheric non-equilibrium plasma, we demonstrated that contact with plasma and the humidification of the treatment atmosphere to promote the generation of hydroxyl radicals are crucial for improving microbial inactivation efficiency. Furthermore, analysis of plasma-sterilized pepper indicated the potential for high-quality dried solid foods through plasma pasteurization.

In ice cream manufacturing, freezing is an extremely important process in determining the internal structure of ice cream. The author considers that the fluid flow induced by agitation during freezing is a governing parameter for various phenomena that occur during freezing, and has investigated the effect of agitation speed on the internal structure of ice cream using a batch-type freezer. This paper presents the author’s investigation about fluid flow, the size change in bubbles/fat globules with time during freezing, and the melting characteristics of the samples. It was found that the agitation speed affects the kinetics of size changes of bubbles/fat globules and the melting characteristics of the samples. Thus, an advanced freezing process can be developed by optimizing the agitation operation.