Nutritive evaluation on chemical components of leaves, stalks and stems of sweet potatoes (Ipomoea batatas poir)

For the effective use of leaves, stalks and stems of two kinds of sweet potatoes, we determined their chemical components and evaluated their nutritive values. Some parts of this plant, which are not usually used, were found to be rich in nutritive and functional components. In particular, leaves contain a large amount of protein, showing high amino acid score. Any part of sweet potatoes was rich in dietary fiber and in particular, leaves were soluble dietary fiber and stems were insoluble dietary fiber, respectively. Mineral content, particularly iron, and vitamin content such as carotene, vitamin B2, vitamin C and vitamin E were high in leaves in comparison with other vegetables. Furthermore, polyphenol content in leaves was comparatively high. These results suggest that the whole parts of sweet potatoes should be utilized as valuable foodstuffs to cope with future changes in food supply and demand, particularly in developing countries.