[in Japanese]

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[in Japanese]

View full abstract

[in Japanese]

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[in Japanese]

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Most vinegars have a strong odor and stimulative taste during the early period of storage after brewing. As they age, their odor and taste become very mild. This interesting phenomenon has been examined in our laboratory. The characteristics of many aged white vinegars have already been investigated using NMR spectra, vapor pressure measurement and DSC thermograms. In this study, the concentration of acetic acid in the vapor of Sherry vinegars stored in barrels for 25 years was investigated in detail. The concentrations of other components in the liquid and vapor of these samples were also analyzed and their effect on the decrease in acetic acid concentration in the samples' vapors was studied. A large decrease in the acetic acid concentration in the vinegar vapor was observed in the presence of ethanol, but ethylacetate, ash and nonvolatile residues extracted from the barrels caused little reduction in acetic acid concentration. The effect of these minor substances on the vapor components of an acetic acid aq. solution with the same level of acidity as the Sherry vinegar samples was investigated in detail. The reduction in acetic acid concentration of the vapor of aged Sherry vinegars was far greater than that produced by the effects of ethanol and other constituents. The mild and non stimulative aroma may be due to a specific liquid state characteristic of aged vinegars, i.e. The formation of a stable molecular cluster which reduces the concentration of monomeric acetic acid molecuies, as indicated the former study on aged White vinegars.

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The authors compared a variety of yeasts used in alcohol beverage production from the standpoint of beer brewing. Firstly, fementability and assimilation tests for sole carbon source and flocculation tests were carried out. Galactose and maltose were fermented and assimilated well, with the exception of sake yeasts. Maltotriose was fermented and assimilated well by beer yeasts and certain of wine yeasts. Beer yeasts flocculated better than the other yeasts. Fermentation tests using wort were then carried out in flasks and fermentation tubes. Not only beer yeasts, but also wine yeasts fermented wort well. Finally, fermentation tests using our pilot plant with a capacity of 100 liters were carried out with the wine yeast and sake yeast which had shown good fermentability in the previous tests. The time required for main fermentation by these yeasts was longer than that required by beer yeast. Wine yeast (Kyokai No.1) produced a phenolic note and high acidity. Sake yeast (Kyokai No.14) produced a significantly estery flavor. It was also found that ferulic acid was transformed to 4-vinyl guaiacol by wine yeasts, like the weizen yeasts, and that sake yeasts produced more isoamyl acetate than the other yeasts.

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In order to commercialize a newly developed recycling process, shochu was made using a fermentor with a working volume of 8, 300l. 1, 500kg of rice was added twice, on the first and the third day, to 5, 300l of post-distillation slurry which had been discharged from the vacuum- distillation process used in the conventional method. No problem was experienced in the newly developed recycling process using a two step addition of cooked rice, although the fermentor volume was increased from 1, 800l to 8, 300l for commercial use. The concentration of ethanol produced in a 7-d fermented mash reached 17.0% v/v and the concentration of glucose was less than 0.4 gl^-1. The 9-d fermented mash was then subjected to vacuum distillation and the production yield of pure ethanol was 470.5ml (kg of added rice)^-1. This value was almost identical to the yield obtained in the 1, 800l-scale experiment reported in our previous paper and was higher than the average yield (450ml kg^-1) obtained with the conventional method. With respect to the quality of the shochu the acetaldehyde concentration and acidity were slightly higher than the value obtained using the conventional method. However, these values decreased during the storage period. The acetaldehyde concentration and acidity were reduced to 25% and 75%, respectively, after a 10-d storage. Also, this shochu obtained a better score in the sensory test than that produced by the conventional method.

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The screening of acid-forming facultative anaerobes for their decolorizing ability with the distilled wastewater (DWDA) produced during the alcoholic fermentation of cane molasses was carried out. On the primary screening, 113 strains, which were isolated from enrichment cultures of various plant and animal samples or soil samples showed decolorizing activity on modified GYP medium containing 10%(v/v) distilled wastewater. Strain SM-3, which was isolated from a soil sample, was selected as the best strain. This strain decolorized 31.4% of molasses pigment at a concentration of 10%(v/v) distilled wastewater supplemented with 1% glucose within 5days at 30°C under semi-anaerobic conditions. The main DWDA was found in the cell-free extract and cell membrane fractions. The strain was identified as Lactobacillus casei from taxonomical studies. Unlike Lactobacillus hilgardii W-NS, decolorization by SM-3 was thought to be based on specific enzymes in the cell membrane fraction which only decolorize the larger molecular weight fractions of the molasses pigment molecules.

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A protease was purified from the sarcocarp of Yubari melon fruit, the raw material used in the production of melon wine, by a series of treatments consisting of ammonium sulfate precipitation, gel filtration and ion-exchange chromatography. The enzyme was a monomer protein without a carbohydrate moiety. Its characteristics are as follws: molecular weight 66 kDa, isoelectric point pH 8.5, optimal temperature 40°C, and enzyme activity is promoted in the presence of Mn²⁺. It is a characterisric serine protease and preferentially hydrolyzes peptide bonds on the carboxyl terminal side of Phe and Arg.
The sequence of the N termcnal 20 amcno acods was determined.

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