Unequal distribution of sugar and starch contents within Japanese processing potatoes during storage

Two potato cultivars, Toyoshiro and Norin-ichigo, which are commonly used in Japan for processing, were stored at 7degC for 3 months, and the sugar (glucose, fructose and sucrose) and starch contents within the potatoes were measured at intervals during storage. The aim of this study was to examine sugar distribution within the potatoes. Regarding reducing sugar (glucose + fructose) or starch contents, a linear relationship was found between that in stem and bud areas of both processing potatoes ; the significant (p < 0.01) relations indicated that the stem end of both cultivars had 2.5 and 1.1 times higher reducing sugar and starch contents, respectively than the bud end during storage.