Disintegration Differences in Cooked Potatoes from Three Japanese Cultivars: Comparison of Starch Distribution within One Tuber and Tissue Structure

Abstract

Differences in the degree of disintegration after cooking were studied in three potato cultivars: Kita-akari, May Queen, and Hokkaikogane. Although the degree of disintegration increased with increase in the starch content in these cultivars, there were even differences in cultivars with identical starch content. For example, at 16%, the disintegration in Kita-akari, according to the standard grades for breeding, was “moderate-complete;” that of May Queen, “moderate;” and that of Hokkaikogane, “none.” Microscopic observations showed that cell separation had occurred in the disintegrated tissues and that the separated cells were full of swollen-gelatinized starch after cooking. Analysis of the starch distribution within a tuber, from the skin to the pith, revealed that cells with a high-starch content appeared in the area outside the vascular ring in Kita-akari but around the ring in Hokkaikogane. The cell size and intercellular space were larger in Kita-akari than in the other two. The results suggest that these structural differences may be one cause of the difference in degree of disintegration among these three cultivars with the same starch content.