Studies of sugar composition and starch morphology of baked sweet potatoes (Ipomoea batatas (L.) Lam).

Sugar composition of seven sweet potato cultivars was successfully analyzed. Fresh CYY95-26 sweet potatoes had the highest (8.41%) total sugar content while TNG73 had the lowest (4.5%). For these fresh sweet potatoes, maltose content was very low (0 ~ 0.39%). Because 49.92 ~ 92.43% of total sugars were sucrose, sucrose was the major sugar composition of fresh sweet potatoes. After the baking treatment, the total sugar content of baked sweet potatoes was dramatically increased due to the formation of maltose. The maltose content significantly increased from 0 ~ 0.39% to 8.81 ~ 13.97% on dry weight basis. Therefore, maltose should be included in calculating the total sugar content. Electronic micrographs of fresh sweet potato samples showed that the size of starch granules was generally less than 20 µm. After the baking treatment, starch granules completely gelatinized.