Abstract
Sweet potatoes prepared by methods, boiling, steaming, and baked in an oven, and a microwave oven were examined by histochemical methods to see whether sweetness was correlated to condition of gelatinized starch. Starch granules within starch-storing cells of cooked sweet potatoes were swelled and fused to fill the interior of starch-storing cells. The gelatinized starch of sweet potatoes boiled, steamed, and baked in an oven stained red to dark brown with iodine stain. The gelatinized starch of sweet potatoes baked in a microwave oven stained blue with iodine stain. The blue-stained granules of gelatinized starch were scattered within red-stained, gelatinized starch. The blue-stained, gelatinized starch existed partially among starch-storing cells. The sweet potatoes baked in an oven at 200 degrees were largest in number in red-stained, starch-storing cells. The sweet potatoes baked in an oven at 140 degrees were larger in number in red-stained, starch-storing cells than those boiled and steamed. The sweet potatoes baked in an oven at 200 degrees tasted sweetest. The sweet potatoes baked in an oven at 140 degrees tasted sweeter than did those boiled and steamed. The sweet potatoes baked in a microwave oven, in which the starch-storing cells stained blue, did not taste sweet. The degree of sweetness in the cooked sweet potatoes appears to correlate with the number of the red-stained, starch-storing cells.
