The production of miso has been decreasing due to changes in eating habits and social environments. In addition, there has been a recent move towards reduced salt intake to diminish lifestyle-related diseases. To maintain the demand for miso, it is important to develop salt-free miso manufacturing technology. Thus, collaborative research involving industry, academia, and the government was conducted to develop salt-free miso. The production of salt-free miso requires the control of lactic acid bacteria, spore-forming bacteria, and hygiene-related bacteria. In addition, it is necessary to propagate specific fermentation microorganisms such as yeast and lactic acid bacteria to improve the taste of miso soup. Here, miso production was divided into two steps. In the high-temperature digestion step, miso was heated to 55°Cand the temperature was maintained for 1 to 5 days. In the second, low-temperature addition and multistage fermentation step, a fermentation microorganism corresponding to the desired product quality was added at a temperature of approximately 10°Cand the fermentation temperature was then raised in multiple steps. The microflora produced in each manufacturing step was analyzed by PCR-DGGE to identify hygiene-related bacteria and lactic acid bacteria. Processing conditions during the high-temperature digestion step were set as the critical control point in manufacturing.

There has been a great deal of interest in adequately controlling digestibility of the ingested foods in the human digestive tract. Gastric digestion plays an important role in the process of food digestion, being strongly affected by both physical and chemical digestion processes. Over the last decade, the importance of in vitro gastric digestion models has been increasing, which is mainly attributed to superior applicability to various conditions as well as better reproducibility of experimental data. The authors developed a human gastric digestion simulator (GDS) that simplifies the antrum geometry and function. The major advantages of the GDS include quantitatively simulated gastric peristalsis and direct observation of the digestion behaviors of food particles in the gastric contents. In this review, we provide a brief overview of the findings obtained through a series of studies using the GDS. First, the current progress of in vitro gastric digestion studies is described. We next introduce the history and development of the GDS and findings on the digestion characteristics of representative foods and food models using the GDS. Further improvement of the GDS could potentially make it a useful tool for designing novel functional foods for which digestibility and release of nutrients and bioactives are well controlled.

In Northern Japan, mackerel is a popular fish, but there is no culture of consuming it as sashimi. The present study aimed to establish a handling method for frozen mackerel that would make full use of freezing technology, give root to a culture of consuming mackerel as sashimi, and improve the value of mackerel. The influence on the freshness of raw materials from being kept in frozen storage conditions over a period of time on K-value^1） and rate of inosinic acid was investigated. The proper thawing method was also examined. As a result, it was revealed that eating mackerel in a sashimi state was possible after defrosting at low temperatures in running water, if highly fresh material was frozen quickly, kept at －30°Cand stored less than 10 months. It might not be easy if only established techniques are used, but we think that the flavor of the Hachinohe mackerel is appealing enough to enable a change in the culture.

Characterization of newly isolated baker’s yeast is important for its commercial use. Metabolome analysis of dough not only provides insight into the function of baker’s yeast in dough, but is also used to characterize baker’s yeast that is isolated from nature. The metabolic profile of dough generates information that contributes to optimal dough fermentation and is useful for improving the dough fermentation process. The control of metabolite production in dough leads to the production of high value-added bread. As baker’s yeast consumes γ-aminobutyric acid (GABA) during dough fermentation, baker’s yeast that does not assimilate GABA is useful for the production of GABA-rich bread.

Heat-induced gel was prepared from emulsified fish oil by adjusting the proportions of protein, water and oil in fish meat surimi. To investigate the effect of the dispersion of fish oil particles in surimi on the physical properties of heat-induced surimi gel, the stirring conditions for surimi and fish oil were changed. It was thus clarified that the gel-forming ability of the emulsified surimi is improved and the oxidation of the fish oil is suppressed by dispersing the oil finely and uniformly in the fish meat surimi. Improvement in gel-forming ability varied depending on the type of oil emulsified and the species of fish used for the surimi paste. Over the years, new products based on these developments have been in high demand in Tokyo. Therefore, using this technology, we developed a tofu-like surimi-based product with a texture like tofu that uses raw soybean powder and soybean oil obtained by grinding soybeans, which have been attracting attention as a health food. The resulting cured surimi, or kamaboko, was named “Tokyo-age”．

We have isolated a new strain of Lactobacillus plantarum from Japanese pickles produced by a farmer in Hokkaido, and have named the strain HOKKAIDO. Our investigation of HOKKAIDO strain revealed several characteristics. The strain exhibits digestive juice tolerance and can survive in the intestine. The strain strongly adheres to human enterocyte-like Caco-2 cells, and cells of HOKKAIDO strain competed with E. coli O-157 cells for adhesion to Caco-2 cells. From several examinations with human dendritic cells, this strain may act to improve immune function. It was found that HOKKAIDO strain is superior in the fermentation of vegetables, fruits, and cereals. These characteristics were exploited to produce foods such as fermented soybean milk, alcoholic beverages using sake lees, and fermented carrot drink. In addition, HOKKAIDO strain as a probiotic was contained in commercial products such as yogurt and a milk substitute for calves.

We developed a “nigori vinegar”, which possesses a rich and mild taste with a pleasant flavor, using only sake kasu. The nigori vinegar is made by fermentation of two kinds of enzyme-treated ginjo sake kasu with Acetobacter and lactic acid bacteria. Acetobacter is known to consume lactic acid, and this activity was suppressed by decreasing the stirring rate during aeration. As a result, the vinegar has a characteristic taste and flavor that is derived from the residual lactic acid, which is not contained in ordinary vinegar.

Hot air drying is conventionally applied for the production of dried fruit; however, hardening and browning of the fruit pulp surface often occurs during processing. We demonstrated that microwave irradiation of Japanese pear pulp or grape, followed by hot air drying, produced high quality semi-dried fruit. Dried Japanese pear produced using this method showed uniform softness and a vivid yellow-orange color. In the case of dried grape products, microwave irradiation pretreatment improved the retention of both skin color (yellow-green and red) and original flavor (such as muscat and foxy). In addition, microwave pretreatment shortened the subsequent hot air drying period by approximately 30% for Japanese pear and 60% for grape. This method could be applied to other fruits such as apple, pear and peach. Dissemination of the method has resulted in commercialization of some dried fruit and confectionary products. However, a system capable of mass production, resulting in reduced production costs, is needed to promote the practical use of this method.

Recently, the demand for commercial Hokkaido rice has been on the rise. Consumers are calling for the development of Hokkaido rice cultivars that are suitable for commercial use, in addition to the popular household varieties. In response, we have been developing new Hokkaido rice cultivars as well as evaluation methods to determine the suitability of these cultivars for commercial use.

1．Definition of suitability for commercial use

From 2009 to 2013, we visited 13 major commercial users of Hokkaido rice and conducted interviews to gain an understanding of the qualities considered essential in commercial rice. All the surveyed companies listed the following four processes in rice production: 1) commercial milling, 2) commercial cooking, 3) rice processing and molding, and 4) storage and distribution prior to consumption. The data demonstrated that in each process, the suitability of rice was evaluated based not only on taste and quality, but also on the unique commercial perspectives of economic efficiency and workability.

2．Development of a method to evaluate the suitability of Hokkaido rice for commercial use

Based on the results of the above survey, we identified the appropriate parameters to evaluate the suitability of commercial rice, as specified by actual consumers. We undertook the development of new evaluation methods that take into consideration economic efficiency (cooking yield) and workability (stickiness), aspects not previously considered. Addition of the parameters from the new evaluation method to the existing parameters of taste and quality is anticipated to make the assessment comprehensive and address the requirements of various commercial users, which include determining the amount of water to be added to achieve low stickiness (workability) and high cooking yield (economic efficiency). The ultimate goal is to select cultivars with reduced stickiness (workability), culminating in the selection of cultivars that have only moderate stickiness and little discoloration (taste and quality).