The objective of this study was to optimize the growth environment for sawdust-based culture of shiitake mushrooms. As conditions during the cultivation stage of production have the largest impact on yield, we focused on this stage and considered the effects of temperature and CO₂ concentration on yield. The effects of varying cultivation temperatures between 20°C and 28°C and CO₂ concentrations between 1,700 and 4,500 ppm were investigated. Maximum spawning was observed at 22°C, whereas CO₂ concentrations did not influence the yield. The previously recommended temperature was 20°C and the recommended CO₂ concentration was under 3,000 ppm. As such, it is apparent that air conditioning utilized in the chilling of spawn can be set at a temperature 2°C higher than previously advised and that ventilation can be reduced. These results will reduce energy inputs while lowering production costs.

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Although “regional microorganisms” are often used in the food industry, such as in sake brewing, there are no reports comparing the characteristics of products obtained using wild and bred microorganisms. The aim of the present study was to evaluate the potential of applying a wild microorganism to Sake brewing. Four strains of Saccharomyces cerevisiae were isolated from the soil in Shikoku Island, Japan. Sake was brewed using these 4 wild-type strains and Sake yeast kyokai No. 7, and the resulting products were analyzed and compared. The Sake meter value (SMV) of the Sake brewed using kyokai No. 7 was +10. In contrast, the SMV of the Sake brewed using the wild strains were from －9.7 to －19.2. Additionally, Sake brewed using the wild yeasts had lower concentration of isoamyl acetate and higher concentration of acetic acid than Sake brewed using kyokai No. 7. The antioxidant activity of Sake was determined as the capacity to reduce copper ion and scavenge free radicals. The antioxidant activity of Sake was weaker than that of red wine and stronger than that of white wine. All wild isolates could be applied to brewing Sake. Sake brewed by wild yeasts had distinguishing organic acid composition. Development of novel brewing methods and breeding of wild yeasts will promote wider application of “regional yeasts.”

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In this study, we aimed to investigate changes in the lipid content of brown rice and its composition of fatty acids during long-term storage, both being factors contributing to the characteristic undesirable odor of stored rice. The effect of subsequently polishing the brown rice on these undesirable odor components was also investigated. The lipid content in the brown rice following long-term storage decreased by up to 24.6%, and the quantity of unsaturated fatty acids extracted from the rice bran flour, derived from the outer layer of the rice grains, decreased by up to 11.2%. After a storage period of more than 3 years, the concentrations of ten volatile components in the brown rice increased significantly. However, when the rice was polished to remove the bran layer, leaving 90% of the original grain, the concentration of these undesirable volatile components fell to less than half that in the brown rice.

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