TUBER

The major edible species of yam of African origin are white Guinea yam (D. rotundata Poir.),yellow Guinea yam (D. cayenensis Lam.),and trifoliate or bitter yam (D. dumetorum Kunth). Edible species from Asia include water or greater yam (D. alata L.), and lesser yam (D.esculenta [Lour.] Burkill). Cush-cush yam (D. trifidaL.)originated from the Americas.White Guinea yam and water yam are the most important in terms of cultivation and use.Yam is grown in about 51 countries in the tropics and subtropics,with yields averaging about 11 metric tonnes/hectare in the major producing countries of West Africa (Nigeria,Cote d’Ivoire,Ghana, and Benin).
“There are different types of yam tubers produced in Nigeria, such as water yam, cocoyam and yellow yam; but the ones needed for exportation are the sweet and pound able ones.
Specification & Grades: Yam specification varies from one buyer to the other in terms of weight,length and diameter. Generally exportable yam should have the following characteristics.

i.Diameter- 3.5-4.Scm

1. Length- 15–40cm
2. No hair(No fibers)
3. No fingers(branches)
4. Very smooth body with no sand(if at all it should be very minimal)
5. No injury(if at all it should be very minimal)
6. Not too big(enough for a family to eat at once)

Uses:

Fresh yam tubers are peeled, chipped, dried, and milled into flour that is used in preparing dough called amala (Nigeria) or telibowo (Benin). Commercial products based on dry flakes or flours from the tuber are produced in Nigeria, Ghana, and Cote d’Ivoire for export and sale in urban areas. Yam tubers can be conveniently processed into yam floor and yam chips & pellets.The consumption of yam flour cuts across cultural,religious and demographic boundaries. It is a cherished delicacy when served in the form of “Semolina” or “Semovita”,with well-prepared

soup. Apart from serving as food, it has a lot of industrial uses. It is used in production of all­ purpose-adhesives. The adhesives are used by producers of cartons,packaging companies and lather and shoe producers. The all-purpose adhesives is produced with yam or cassava starch. Some industries particularly in Europe use yam flour in preparation of high quality biscuits, bread, cakes to mention but few.In Nigeria also, it is used in production of high quality bread and cakes. The yam chips and pellets can also play the same function as cassava chips & pellets in production of livestock feeds. Yam Starch has a lot of industrial uses.