บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Relationship between differences in the ease of removal of astringency among fruits of Japanese persimmon (Diospyros kaki Thunb.) and their ability to accumulate ethanol and acetaldehyde.

Taira, S.; Satoh, I.; Watanabe, S.;

Journal of the Japanese Society for Horticultural Science Year: 1992 Vol: 60 Issue: 4 Pages: 1003-1009 Ref: 10 ref.

1992

บทคัดย่อ

Relationship between differences in the ease of removal of astringency among fruits of Japanese persimmon (Diospyros kaki Thunb.) and their ability to accumulate ethanol and acetaldehyde.

Maturing fruits of cv. Yokono (pollination constant and astringent type, PCA), Hagakushi (PCA), Kuramitsu (PCA) and Monpei (pollination variant and astringent type, PVA) were picked from mature trees on 6 Oct. 1990. Fruits from cv. Hiratanenashi (PVA) were picked on 15 Oct. The treatment for removal of astringency involved placing individual fruits in a 900-ml chamber kept at 20 deg C and containing either 10 or 30% ethanol. Chambers for Monpei fruits (which were the heaviest) contained 5 ml of both ethanol concentrations, to give 2.9 and 8.6 ml ethanol/kg fresh fruits. The ethanol concentrations for the other cultivars were adjusted in proportion to fruit weight. In separate treatments, fruits were kept in 20-litre chambers containing 80% CO2. The rate and amount of fruit softening during ethanol treatment varied depending on the cultivar; Hagakushi treated with 10 and 30% ethanol softened as quickly as Hiratanenashi treated with 30% whereas Monpei softened gradually. Fruits treated with CO2 remained firm. The decrease in fruit tannin content (i.e. astringency) seemed to bear little relation to the initial levels. Fruits of Kuramitsu in 30% ethanol and the other cultivars in 10% ethanol were still somewhat astringent after 6 days. Soluble tannins decreased faster with CO2 than ethanol and the rate of decrease was closely related to flesh acetaldehyde concentration. The coagulation response time of fruit juices to acetaldehyde vapour was about the same for all cultivars. It was suggested that tannins polymerise readily in those cultivars which accumulate acetaldehyde rapidly to high levels and that the soluble tannins concentration decreases slowly because of slow ethanol penetration through the skin and/or slow metabolism of alcohol to acetaldehyde.