Relationship between Invertase Activity and Sugar Composition of Persimmon Fruit

Abstract

Relationship between invertase activity and sugar composition of non-astringent persimmon 'Fuyu' and astringent persimmon 'Koshu Hyakume' was investigated. (1) When the persimmons were homogenized sucrose in 'Fuyu' was completely hydrolyzed to glucose and fructose for 20min at 30°C, while in 'Kosyu Hyakume' it was hydrolyzed for 10min at 45°C. (2) Optimum pH and temperature of invertase was about 5.0 and 45-50°C for both of the persimmons. (3) The Km values for 'Fuyu' and 'Koshu Hyakume' persimmons were 7.85mM and 2.25mM respectively. (4) Invertase activity of 'Fuyu' persimmon was considerably lower than that in the astringent persimmons, i.e. 'Koshu Hyakume', 'Hachiya', 'Ebo', 'Mizugaki' 'Kairyoshibu' and 'Yamato Hyakume'. Whereas the ratio of sucrose content to total sugar content of 'Fuyu' was higher than that of the astringent persimmons. (5) Among the six astringent persimmons, the ratio of sucrose content to total sugar content was not related to the enzyme activity. (6) In 'Fuyu' persimmon invertase acti ity did not change during maturation but increased during storage at room temperature. The ratio of sucrose content to total sugar content decreased gradually during maturation and storage.