[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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Twenty-six yeast strains were isolated from about 2,000 flowers of "Kurume Tsubaki MASAYOSHI" by using a YPD liquid medium（pH 4.0, 5% ethanol concentration）. Strain Q 20 was selected for its sugar fermentation ability and productivities of ethy caproate, isoamyl alchol productivity, daiacetyl, and acetoin. Strain Q 20 was identified as Saccaromyces cerevisiae by genetic analysis of the 26S rRNA D1/D2 domain. A celrenin-resistant mutant Q 20-19 derived from Q 20 by UV irradiation was finally selected for rice shochu making. The prototype rice shochu made with the Q 20-19 strain had a strong ginjyo aroma and a mild taste.

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The study investigated the distribution of monoterpene glycoside in a sweet potato tuber. The steamed tuber was divided into 11 parts and powdered after being freeze-dried. Monoterpene glycoside-rich fractions were extracted from the freeze-dried samples using methanol. This fraction was subjected to GC-MS analyses to quantitative liberated monoterpene alcohol before and after enzyme treatment. Nerol and geraniol were liberated efficiently by β-glucosidase while linalool and α-terpineol were done so by β-primeverosidase. However, citronelool was not liberated by either enzyme treatment. These results showed that the monoterpene alcohols except for citronelool existed as glycosides in sweet potato tuber. Consequently, nerol, geraniol, linalool, and α-terpineol contents were compared between different parts of the tuber. The greatest amount of nerol was liberated from the center part of tuber, comprising 38% of the total nerol content. Meanwhile, geraniol, linalool, and α-terpineol were mainly distributed to the skin part, respectively comprising 37%, 66% and 60%. Our results further showed that the center part of the tuber had relatively small amounts of linalool and α-terpineol; in particular, linalool was not found in the center part. These results showed that the distribution of monoterpene glycoside differed among the tuber tissues.

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