FREE SUGAR COMPOSITION OF SWEET-POTATO CULTIVARS AFTER STORAGE

The concentrations of fructose, glucose, sucrose, and maltose in sweet potato (Ipomoea batatas (L.) Lam.) roots, following an 8-month storage period, were assessed by high performance liquid chromatography (HPLC ). Imported cultivars and breeding lines were compared in both the raw and cooked state against New Zealand standards. Strong linear relatio nships were demonstrated between concentrations of the sugars (fructos e, glucose, and sucrose) in cooked roots, and the corresponding sugars in raw roots (R-2 of 93.5, 93.8, and 88.8% respectively). The relativ e proportion of fructose to glucose 0.44 : 0.56 was very stable across all cultivars, and independent of the total concentration of the thre e sugars-fructose, glucose, and sucrose. The negative relationship bet ween sucrose and the levels of fructose + glucose was significant (P < 0.001) excluding cultivars 'Jewel' and 'Toka Toka Gold'. All of the c lones produced considerable amounts of maltose during cooking, which w as significantly (P < 0.001) related to % dry weight. Using canonical variates to group the clones, 'Owairaka Red', the New Zealand standard cultivar, was shown to cluster with the Japanese cultivar, 'Beniazuma ', and the Taiwanese breeding line, '93N12/1', on the basis of high dr y matter and low fructose + glucose levels. The minor New Zealand cult ivar, 'Toka Toka Gold', clustered near the North American cultivar, 'J ewel', on the basis of low maltose, high sucrose, and medium dry weigh t. 'Toka Toka Gold' had a higher fructose + glucose than its sucrose c oncentration would predict, as well as a lower maltose level than esti mated from its dry matter content.