[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Water absorption, and swelling of polished barley as raw material of shochu were studied on 6 varieties. The maximum volume of water absorption was between 53% and 60%. Nishinochikara showed the largest volume, and Daisengold, and Mihogolden showed the smallest value among barleys tested. The maximum absorption volume was not affected by the temperature of steeping water, but was varied with varieties, and it was also affected by the moisture content of polished barley when compared in the same variety. Swelling rate after 6 hr. of steeping was clearly different for two row and six row barleys, and Minorimugi, a six row, showed the higest value. In two row barleys, the absorption rate was represented by the equation, Y =aX^b, where X represent time and absOrption rate, Y absorption rate respectivety, and a and b are coefficient obtained for each variety. According to this expression, the time to reach an absorption rate 35% was varied by the temperature of steeping water to be about 20-45 min., and varied by the variety to be about 17-45 min. at 30-15°C. The change in absorption rate was represented by the Total Temperature (the product of the temperature (°C) and time (min.)). It was suggested to be a useful factor, because the time of steeping could be set up according to the temperature of steeping water from the total temperature.

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Soy sauce koji autolyzed at 55°C for 48 hr was applied to a new soy sauce making. For the establishment of a new soy sauce making system, preliminary experiments on lactic acid fermentation by Pediococcus halophilus and ethanol fermentation by Zygosaccharomyces rouxii were carried out using the heterogeneous soy sauce koji autolyzate with the addition of sodium chloride and glucose, the pre-fermentation mash as a fermentation substrate.
Experimental results obtained were as follows: Lactic acid production depended on salt concentration of the pre-fermentation mash, and lactic acid was produced more rapidly at lower salt concentration of the mash. Z. rouxii grew well in the pre-fermentation mashes adjusted to pH between 4.0 and 6.0 and produced more than 2 g of ethanol/dl of mash at 30°C after 17 days. Lactic acid fermentation was induced by inoculation of 10⁵-10⁶ P. halophilus cells/ml of the pre-fermentation mash, and after 14 days incubation ethanol fermentation was induced by inoculation of 10⁵ Z. rouxii cells/ml of the mash. The amounts of lactic acid and ethanol produced were 1.05 g and 2.27 g/dl of the filtrate of the fermented mash, respectively. Chemical composition of the filtrate was similar to that of the conventional raw soy sauce. Therefore, the establishment of a new soy sauce making system using the autolyzed soy sauce koji was suggested to be possible.

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Proton-pumping activity of a Zygosaccharomyces rouxii, AN 39, grown in YPD medium decreased extensively in 15% NaCl solution, while that of a Saccharomyces cerevisiae, NA 87-11 A, declined in 8% NaCl. However, ATPase of the plasma membrane from NA 87-11 A was somewhat more tolerant toward NaCl than that from AN 39. AN 39 cells grown in YPD medium containing 5% NaCl showed high proton-pumping activity in 15% NaCl, whereas NA 87-11 A cells grown in the same medium did no increase of proton-pumping activity in 10% NaCl. NA 87-11 A cells incubated in 10% NaCl solution accumulated smaller amount of ATP, that is, less than one-third of AN 39 cells. A NaCl-hypersensitive mutant of Z. rouxii, 152 S, which was defective in a Na+-excretion mechansim and could not grow in YPD medium containing more than 1% of NaCl, showed approximately the same level of ATP and proton-pumping activity in 10% NaC1 solution as the wild type, AN 39. On the other hand, another salt-sensitive mutant of Z. rouxii showing altered sterol composition, TN 3, accumulated high level of ATP whereas exhibited low proton-pumping activity in 10% NaCl solution, although NaCl tolerance of ATPase of plasma membrane from this mutant was the same as that from AN 39. These results suggest that the low proton-pumping activity of plasma membrane ATPase and low level of intracellular ATP of NA 87-11 A in NaCl solutions of high concentrations are concerned with low salt-tolerance of S. cerevisiae. It is also suggested that the proton-pumping activity of plasma membrane ATPase in intact cells incubated in NaCl solution is not correlated with the salt-tolerance of ATPase in isolated plasma membrane, and that plasma membrane composition, such as lipid composition, is important in the salt-tolerance of yeast, since it may affect the proton-pumping activity.

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Several strains of yeasts showing strong and weak fermentation abilities on isomaltose and isomaltotriose were separated from Kyokai No.7 yeasts and general characteristics including color formation in TTC media of these yeasts and ingredients of sakes produced by using them were examined. Since glucose concentration in moromi was extremely high, the sakes obtained showed no difference in isomaltose and isomaltotriose contents. The acidity of TTC Pink strains in isomaltose and isomaltotriose media was higher than that of Red strains. This difference was caused by the difference in malic acid contents. With respect to aroma ingredients, iso-amyl alcohol content of the Red strain did not differ from that of the Pink strain, while the iso-amyl acetate content and isoamyl acetate/iso-amyl alcohol ratio of the Red strain were somewhat higher than those of the Pink strain.

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A sparkling sake containing CO₂ gas generated by yeast growth was produced from a sake with sake meter +3, acidity 1.8, amino acidity 0.9, reducing sugar content 2.2% and alcohol content 10.2%. The sake was inoculated with yeast, bottled, sealed tightly, and incubated at 25°C. A yeast which aggregates granularly and does not stick to the bottom of the bottle was used. Analysis of this sparkling sake indicated CO2 gas pressure 2.3-3.0 kg/cm2, sake meter +10, acidity 2.2 and alcohol content 10.4%. Taste was cool and fresh owing to the stimulus of CO2 gas. When the bottle was shaken lightly, granular yeast cells floated in the bottle, giving the appearance just as snow.

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