*2.4.6 Dioscorea rotundata Poir (white yam)*

This yam specie is native to Africa. It produces edible tubers that possess economic importance [55]. It is among the most important cultivated yam species and it is mostly consumed in West Africa and Cameroon [56]. It has a long shelf-life which makes it available all year round. White yam are subjected to different cooking methods in Western and Central Africa, however, the most common ones are boiling, frying and roasting [29]. It is mostly used in Africa for the traditional popular dish known as "iyan" (pounded yam). Sun-drying of parboiled yam pieces and then milled into a light-brownish powder (*elubo*) is another method of processing

in Nigeria. A thick brown starchy paste known as" *amala"* which is consumed with local soups and sauces can be prepared from the light brown powder [55].

### *2.4.7 Dioscorea trifida (cush-cush yam)*

This specie is a native of Guyana region of South America and it is the mostly referred to as "New World" yam, their growth cycle is less related to seasonal changes than other yam, since they originated from the tropical rain forest. They can be easily cultivated when compared to other yams and also they have good flavor, which may serve as a great potential for increase production [54, 57]. Its starch contains amylose content in the 34.7–43.3% range for white and purple varieties [57].
