Quality Changes of Dioscorea alata L. Tuber during Storage

Abstract

[KaU-09], one clone of Dioscorea alata L., was grown in Kagoshima district and freshly harvested tubers were stored at different temperatures to examine the effect of storage condition on the quality of yam. Judging from external appearance of tuber during the storage at 15°C, 13°C and 10°C, it was suggested that appropriate storage temperature was 15°C, and at this temperature the tubers were stored for 6 months in healthy condition. The tubers stored at 10°C became soft at all parts and their cut section showed grayish color which was different from the creamy white color of the healthy tubers. On storage at 13°C injury was observed as the appearance of spots on the surface. In the course of 5 month-storage at 15°C, the content of viscous polysaccharides in the tuber decreased linearly (to 70% of the initial content) followed by the change in rheological properties (apparent viscosity, thread forming capacity) of the homoginate of yam, called "Tororo" in Japanese. On storage at 10°C, the tubers lost the viscous property, and this was assumed to be due to change in the property of viscous polysaccharide molecules. Amylase activity of the tuber stored at 15°C reached the maximum (3.5 times of the initial activity) after 8 month-storage.