[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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A test brewing was made by the ampuled pure yeast method, in which culture liquid of Rhizopus sp. was used instead of lactic acid in preparing moto (yeast starter). When culture liquid made by culturing Rhizopus javanicus TUA 055, or R. tonkinensis TUA 192 at 30°C for 3 days under aeration was added to the mizu-koji (mixture of koji and water), the growth of putrefactive bacteria, Lactobacillus casei B 83, was completely inhibited. A mizukoji made from rice koji 0.1kg, culture liquid of Rhizopus sp. or lactic acid solution (acidity 20.5 ml) 0.1l, and water 0.8l was applied as the soe (first addition) with ampuled pure yeast in test brewing with total rice 5 kg. General components of sake made by adding culture liquid of Rhizopus were not different from those of sake made by lactic acid solution. As to the organic acid composition, lactic acid content was lower, and malic and succinic acid contents were higher in sake with the addition of culture liquid of R. javanicus than others, though the difference did not give any appreciable influence on the taste of sake.

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Effects of additives and stirring on the formation of flavor components were studied during the fermentation of saccharified solutions. Solutions prepared from steamed naked barley by enzymatic saccharification were fermented under the addition of active carbon with stirred or standing condition, and the formation of isoamyl alcohol and isoamyl acetate in sake was examined.
The fermentation rate was higher and the yeast cell number was increased with stirring in control and mash added with carbon than those without stirring. The consumption of leucine and the formation of isoamyl alcohol formed were increased in proportion to the increase in yeast cell number.
The amount of isoamyl alcohol formed was the largest in fermentation of carbon-added mash with stirring.
On the other hand, the increase in isoamyl alcohol did not lead to the increase in isoamyl acetate, because AATFase (alcohol acetyl transferase) activity in the mash was decreased with stirring.
The formation of isoamyl acetate was the highest in carbon-added mash without stirring, in spite of lower formation of isoamyl alcohol than that with stirring. It is due to the result that AATFase activity was not lowered by stirring in this mash.

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A new method to immobilize both mycelia and extracellular enzymes was developed by using nonwoven fabrics as support materials. Aspergillus oryzae AHU 7141 producing extracellular amylase and protease was employed in the experiments and cultivated in air on a growth medium absorbed on non-woven fabrics. Eight kinds of non-woven fabrics made of natural or synthetic fibers were tested, and those which made of fibers containing functional groups such as-NH₂ and-COOH were found to be good for the immobilization of both mycelia and enzymes produced. The highest activity of immobilized amylase was obtained by using a non-woven fabric made of a modifird acrylic fiber in which 50% of-CN was substituted by-COOH. The immobilized amylase was tested for the hydrolysis of starch by a repeated batch method in the presence of dissolved oxygen as high as 180 ppm in the reaction system to suppress the further growth of immobilized mycelia and microbial contaminants. The hydrolysis reaction was successfully repeated more than 40 times in a period of more than 1, 000h, and very little decrease was observed in the activity of immobilized amylase even after the repeated use. Moreover, protease produced by this strain was also successfully immobilized by this new method.

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