| Abstract: | “Sweet potato” (var. Jersey) and “Yam” (var. Garnet) are mealy (dry) and soggy (moist) varieties, respectively, of Ipomoea batatas Poir. (Convolvulaceae). The raw fleshy roots of both varieties have essentially similar quantities of all measured variables except for cellulose, hemicelluloses, and amylose. On baking, only the amounts of non-reducing sugars and possibly cellulose appear unchanged, while the reducing sugars increase markedly in both varieties, with those of the yam far exceeding those of the sweet potato. The yam's starch content (particularly the amylose fraction) falls faster and to a lower level; its water-soluble pectin content increases; and its hemicellulose content is particularly decreased. Scanning electron microscopy (SEM) showed that the cell walls of the raw fleshy roots of both varieties are coated with long parallel fibrils, 0.25–1.5 μm in diameter, which appear to be hemicellulosic. |
