Application of High-Pressure Treatment to Enhancement of Functional Components in Agricultural Products and Development of Sterilized Foods.

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".

Surface complexation reactions of inorganic anions on hydrotalcite-like compounds.

Complexation reactions of environmentally important inorganic anions such as nitrate, chloride, sulfate, arsenate, and phosphate on the surface of hydrotalcite-like compounds (HT) were investigated to understand the role of HT in the immobilization of hazardous anions in an alkaline environment. The effects of surface complexation reactions on the solid state properties of HT were also evaluated to understand their stability. Synthetic HT was used for the adsorption and post-adsorption experiments. The obtained adsorption isotherms showed that the order of selectivity of HT for anions was NO(3)

Change of thermal inactivation of Clostridium botulinum spores during rice cooking.

Cooked and packed rice (CaPR), a popular rice product in Japan, is distributed with oxygen-absorbing agents and without refrigeration. When the final product was inoculated with spores of several strains of proteolytic Clostridium botulinum at a dose of 10(3) spores per g (2 x 10(5) spores per package) and incubated at 30 degrees C, the bacteria grew and produced neurotoxins in 40 days. To simulate more realistic cases of contamination, the same dose of spores was inoculated before the cooking process. When cooked at 100 degrees C for 30 min, a small number of spores survived and the toxins were detected in some of the samples after incubation for 180 days. However, when cooked at 100 degrees C for 15 min immediately followed by 105 degrees C for 15 min, neither survivors nor the toxins were detected during incubation for 270 days after cooking. Even when inoculated with 10(5) spores per g of one of the most heat-resistant strains, 213B, viable spores were not detected after cooking. The inactivation by these heating conditions in different media indicated that the spores were inactivated >1,000-fold more in rice suspension than in cooked meat medium or phosphate buffer. It was therefore suggested that rice contains component(s) that facilitates thermal inactivation of C. botulinum.

Three Dact gene family members are expressed during embryonic development and in the adult brains of mice.

Members of the Dact protein family initially were identified through binding to Dishevelled (Dvl), a cytoplasmic protein central to Wnt signaling. During mouse development, Dact1 is detected in the presomitic mesoderm and somites during segmentation, in the limb bud mesenchyme and other mesoderm-derived tissues, and in the central nervous system (CNS). Dact2 expression is most prominent during organogenesis of the thymus, kidneys, and salivary glands, with much lower levels in the somites and in the developing CNS. Dact3, not previously described in any organism, is expressed in the ventral region of maturing somites, limb bud and branchial arch mesenchyme, and in the embryonic CNS; of the three paralogs, it is the most highly expressed in the adult cerebral cortex. These data are consistent with studies in other vertebrates showing that Dact paralogs have distinct signaling and developmental roles and suggest they may differentially contribute to postnatal brain physiology.

Dorz1, a novel gene expressed in differentiating cerebellar granule neurons, is down-regulated in Zic1-deficient mouse.

The Zic1 gene encodes a zinc finger protein that controls vertebrate neural development. A previous study showed that Zic1 is expressed in developing and mature cerebellar granule neurons, and that Zic1-deficient cerebellum is hypoplastic and lacks a lobule of the anterior lobe. In the present study, we searched for genes de-regulated in the cerebellum to understand the molecular basis of cerebellar development. A novel gene, Dorz1, was identified and characterized as one of the most significantly down-regulated genes in Zic1-deficient cerebellum by the DNA microarray analysis. The expression of Dorz1 in the developing cerebellum peaked at embryonic day 17.5, and at that stage Dorz1 transcripts were detected in cerebellar granule neuron precursors where Zic1 expression is enhanced. In addition, Dorz1 expression was up-regulated in cultured cells overexpressing Zic1. These results suggest that Dorz1 expression is positively regulated by Zic1 during cerebellar development.

Zic2 controls cerebellar development in cooperation with Zic1.

Mouse Zic genes encode zinc finger proteins and are expressed in the developing and mature CNS. Reduced expression of Zic2 in mice results in spina bifida and holoprosencephaly. However, the disruption of Zic1, a strong homolog of Zic2 that has an overlapping expression pattern, results in cerebellar malformation with no apparent abnormalities in the forebrain or in posterior neuropore closure. Here we revealed that Zic2 and Zic1 cooperatively control cerebellar development by regulating neuronal differentiation. Both Zic1 and Zic2 are expressed in the precursor cells of the granule neuron and the neurons in cerebellar nuclei. Mice carrying one mutated Zic1 allele together with one mutated Zic2 allele (Zic1(+/-)Zic2(+/kd)) showed a marked cerebellar folial abnormality similar to, but distinct from that found in mice homozygous for the Zic1 mutation (Zic1(-/-)). The Zic1(+/-)Zic2(+/kd) cerebellum is missing a lobule in the anterior vermis and has a truncation of the most posterior lobule. Expression of transverse zonal markers is shifted anteriorly in the developing cerebellum, indicating that the anterior part of the cerebellum is poorly developed. Abnormalities in the developing Zic1(+/-)Zic2(+/kd) cerebellum share the following features with those of the Zic1(-/-) cerebellum: a preceding reduction of cell proliferation in the anterior external germinal layer, a reduction in cyclin D1 expression, and enhanced expression of the mitosis inhibitors p27 and p16, and enhancement of Wnt7a expression. These results indicate that Zic1 and Zic2 may have very similar functions in the regulation of cerebellar development.