In 1988, the late Prof. Rikimaru Hayashi had first proposed "Use of High Pressure in Food", introducing his views, i.e., "heat and pressure are independently capable of transforming the state of a substance, and such state transforming factors are only heat and pressure in nature." Sc. D. Masaru Nakahara stated in his note that he had been impressed by the unique starting point of Prof. Hayashi's idea. Prof. Hayashi had explored some good method for food processing without using heat, so he alternatively thought of high-pressure treatment (Hayashi R (1989) Use of high pressure to food processing and preservation. In: Hayashi R (ed) Use of high pressure in food. San-Ei Publishing Co, Kyoto, pp 1-30; Nakahara M (1990) Water and ions at high pressure: their fundamental properties relevant to the pressure treatment to food. In: Hayashi R (ed) Pressure-processed food--research and development. San-Ei Publishing Co, Kyoto, pp 3-21). Since the start-up of Japanese research group of high pressure in biological field (the present "Japanese Research Group of High Pressure Bioscience and Biotechnology (JHPBB)") and "International Association of High Pressure Bioscience and Biotechnology (IAHPBB)", we have continued to research into the industrial use of high-pressure treatment over a period of 25 years to realize our dream, that is, the same as Prof. Hayashi's dream. Although heat and pressure were found to be independent factors capable of transforming the state of a substance, use of heat has been overwhelmingly more frequent in food processing up to now. However, the pressure treatment has the advantages of instantaneous transmission, uniform distribution in vessels, and ability of inducing uniform change in quality. The high-pressure treatment does not cause cleavage of the covalent bond in the substance, thereby lessening the decomposition of nutrients, the generation of offensive smell, and the production of abnormal materials when compared with the heat application. In addition, energy consumption in the high-pressure treatment is less than that in the heat treatment. For the reasons mentioned above, the high-pressure treatment has thus been regarded as suitable for future food processing, and much attention has been paid to the researches of high-pressure treatment again. Then, we reviewed the previous researches in which little interest had been taken because of imperfectness of non-heat sterilization. Surprisingly, we discovered some novel findings about the effect of high-pressure treatment, that is, pressure history on the subsequent event. Then, we decided to present two theses on the themes, "Application of High-pressure Treatment to Enhancement of Functional Components in Agricultural Products" and "Application of High-pressure Treatment to Development of Sterilized Foods".

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Yeast strains isolated from different Kimchi products were indicated to belong to Kazachstania (Saccharomyces) servazzii by their rRNA gene sequences. One isolate, the strain MK1 was used to obtain the hydrostatic-pressure sensitive mutant, MK1-HPS, by repeating three cycles of 100-MPa hydrostatic-pressure treatment for 10 min and selection of colonies appeared in a delayed fashion after treatment. MK1-HPS was significantly sensitive to hydrostatic-pressure treatment, and it formed no colonies and did not produce gas in an airtight-sealed culture after 200-MPa hydrostatic-pressure treatment for 60 min. MK1-HPS exhibited the similar fermentation activity as MK1. Production of Kimuchi using MK1-HPS is expected to suppress gas formation during storage after high-pressure treatment.

This paper described the cases where a high-pressure treatment of 200 MPa was found to be effective against the two typical heat-resistant spores, B. subtilis and B. cereus when conducted as a pretreatment step before heat sterilization at 90 to 100°C. In addition, when the B. cereus was used as the indicator, it took 36 minutes (D＝3 min.) to complete the heat sterilization at 100°C, whereas the holding time of only 6 minutes (D＝0.5 min.) was enough to achieve sterility by using the Hi-Pit (high-pressure induced transformation) effect.

High static pressure is thought to be the promising technique to control fermentation. The effect of high pressure treatment on the composition of microbial flora during kimchi fermentation was examined using denaturing gradient gel electrophoresis of PCR-amplified DNA followed by nucleotide sequencing of the amplicons. Eleven lactic acid bacteria (LAB) strains, including Lactobacillus, Leuconostoc and Weissella species, were isolated from kimchi. During the 60-day fermentation period, a two-stage decrease of pH to 3.9 was observed. The cell concentration of LAB reached the maximum on the 15th day, and was maintained at 3.2×10 8 cfu/ml thereafter. Among LAB, Lactobacillus sakei was consistently observed, and Lactobacillus plantarum was observed after the 21st day. The cell concentration of yeasts reached the maximum of 1.4×10 8 cfu/ml on the 15th day and decreased to an undetectable level after the 27th day. Kazachstania servazzii was overwhelmingly dominant. When 200 MPa high pressure treatment was applied for 60 min to the kimch on the 21st day, further decrease in pH was not observed. Cell concentrations of LAB and yeasts were suddenly reduced to 8.3×10 5 cfu/ml and an undetectable level, and recovered gradually and rapidly, respectively. Apparent difference in the microbial flora between the pressure-free and-treated samples were not observed. Addition of L. sakei and K. servazzii at the start of fermentation did not produce an apparent effect.