In this study, we investigated the development of a GABA enrichment technology for rough rice by the application of water and temperature optimization. The following findings were obtained: (1) In the water storage test, there was a positive correlation between storage temperature and GABA content.(2) GABA content increased as post-storage moisture increased in the 60 °C and 65°C test plots.(3) Efficient GABA enrichment could be achieved by storing the rough rice at 60 °C, 98 %RH for 5 hours or 65 °C, 98 %RH for 3 hours at a high moisture content.(4) When 1.5 % rice vinegar was added to the water, GABA enrichment could be achieved at 55°C for 5 hours.(5) The taste of the rice in the vinegar-added sample was similar to that of the control sample, except for the aroma and overall evaluation, suggesting an improvement in eating quality. In addition, it is considered possible to develop a product with a limited application (GABA rice for sushi).

The production of isoflavone aglycones (IA) from isoflavone glucosides by a commercially available Bacillus subtilis (natto) strain and β-glucosidase activity associated with the reaction were examined using various media. These results were compared with those using B. subtilis strain 168. Some production of IA by B. subtilis (natto) in semi-solid soybean medium was shown; however, almost no production was observed in solid soybean medium. B. subtilis 168 produced IA abundantly in both media. Regarding fermentation in both soybean media, β-glucosidase activity was much lower in B. subtilis (natto) than in B. subtilis 168. When using liquid soybean medium, similar amounts of IA production were observed in both strains at similar culture incubation times (after the middle of fermentation). However, β-glucosidase activity was significantly lower in B. subtilis (natto) than in B. subtilis 168. In LB medium containing isoflavone glucosides (LB-DG medium), β-glucosidase activity of B. subtilis (natto) or B. subtilis 168 cultured in LB-DG medium supplemented with 0.2 % glucose at the early stage was significantly higher than that with no added glucose. Thus, B. subtilis (natto) can be a starter for IA production in semi-solid and liquid soybean medium, and the low IA content in natto (fermented soybean) products could be attributed to not only low β-glucosidase activity, but also a delay in IA production, which does not depend on β-glucosidase activity, during fermentation with B. subtilis (natto). Furthermore, the glucose content in soybean media might affect IA production during fermentation with Bacillus subtilis.

The aim of this study was to identify factors that need to be controlled in order to make barley flour-blended bread with superior expansion properties, without using gluten. Fourteen types of barley flour were prepared by combining four barley cultivars and four milling methods. A breadmaking experiment was conducted at a practical scale, where the 14 flours were mixed in percentages ranging from 10 % to 50 %. The milling conditions required to make barley flour with superior expansion properties included using a low-temperature milling technique, which does not gelatinize starch grains, and a fine grinding technique. A negative correlation was observed between the expansion properties of the flours and the total amount of dietary fiber in the bread. Important factors affecting the expansion properties of breads made with mixed barley flours appeared to be 1) the crushed state of the cell walls and the dietary fiber contained in barley flour, the main constituents of which are β-glucan and arabinoxylan, and 2) the total amount of dietary fiber contained in barley flour-blended breads.

The purpose of this study was to investigate the applicability of starches from various botanical sources as a substitute for kudzu flour in the production of brown rice tofu. In sensory analysis, potato starch and tapioca starch were suggested as a possible alternative to kudzu flour among the tested starches. Additionally, textural analysis indicated that the adhesiveness of the tofu prepared using potato starch was remarkably high when compared with that using tapioca starch. Thus, it was revealed that tapioca starch was the best substitute for kudzu flour in brown rice tofu production.