The YamYam is an ambiguous vernacular name indicating several species of plants belonging to the Dioscorea kind, family of Dioscoreaceae, cultivated in all the tropical areas of the sphere for their edible tubers rich in starch. The term also indicates the tuber itself consumed as a vegetable-root. In North America and in Quebec, what is called yam is often, in reality, a sweet potato.
CompositionThe chemical composition of the tubers is close to that of potatoes with approximately 25% starch, but a little more proteins (approximately 7%, four times more than the cassava). They are very low in fat and minerals, and rather rich in vitamin C. Certain varieties, used by pharmaceutical industry, contain substances of three types:
- - alkaloids, like dioscorine,
- - tannins,
- - sapogenins, like the diosgénine which is also used in laboratory with other components for the preparation of steroids, similar in particular to cortisone, progesterone and oestrogens, once transformed.
As for the natural diosgenine of the yam, it has shown in various studies that it intervenes as lipophylic antioxydant and contributes to the good transformation of food sterols, which are sources of the endogenous steroid hormones. The species of yams for feeding use or in food supplement are mainly Dioscorea alata and Dioscorea opposita
Ivory Coast produces on average 3,000,000 Tons ; that is 8% of the world production