Yam is the common name for some species in the genus Dioscorea(family Dioscoreaceae). These are perennial herbaceous vines cultivated for the consumption of their starchy tubers. Yams of African species must be cooked to be safely eaten, because various natural substances in raw yams can cause illness if consumed. The most common cooking method in Western and Central Africa is by boiling, frying and roasting the yam. Yams have a very starchy and slippery texture. Creamy or firm when cooked, yams have an earthy, hardy taste and usually a minimal amount of sweetness. The tubers can be stored up to six months without refrigeration, which makes them a valuable resource for the yearly period of food scarcity at the beginning of the wet season.
There are over a hundred and fifty varieties of yams available worldwide but in Cameroon, we recognize but a few which thrive better in our climatic conditions;
White yam (D. rotunda): originated in West Africa. It is considered to be one of the four most important food yam varieties in West Africa, where it is thought to be the best for making the national dish of “fufu”. The White stores better than the Yellow and is more tolerant of the long dry season typical of West Africa. The white variety has moister, softer flesh than the yellow.
Yellow yam (D. cayensis) :is indigenous to the forest zone of West Africa which has a short dry season. It requires a full year for maturity and is considered one of the most important yam types in the world. Grown mainly in Africa and the West Indies, it is not as popular as the white.
Tuber is the main part of the yam plant which has high carbohydrate content (low in fat and protein) and provides a good source of energy. Unpeeled yam has vitamin C. Yam, sweet in flavor, is consumed as boiled yam (as cooked vegetable) or Fufu or fried in oil and then consumed. It is often pounded into a thick paste after boiling and is consumed with soup. It is also processed into flour for use in the preparation of the paste. Its medicinal use as a heart stimulant is attributed to its chemical composition, which consists of alkaloids of saponin and sapogenin. Its use as an industrial starch has also been established as the quality of some of the species is able to provide as much starch as in cereals.
Yam provides around 110 calories per 100 grams of product.Yam is high in vitamins C and B6, potassium, manganese and dietary fiber while being low in saturated fat and sodium. A product that is high in potassium and low in sodium is likely to produce a good potassium-sodium balance in the human body, and so protects against osteoporosis and heart disease.
- Yams are a good source of potassium, a mineral that helps to control blood pressure.
- Yams are a good source of vitamin B6. Vitamin B6 is needed by the body to break down a substance called homocysteine, which can directly damage blood vessel walls. High intakes of vitamin B6 have also been shown to reduce the risk of heart disease.
- Yams’ complex carbohydrates and fiber deliver the goods gradually, slowing the rate at which their sugars are released and absorbed into the bloodstream. In addition, because they’re rich in fiber, yams fill you up without filling out your hips and waistline.
- Yams are a good source of manganese, a trace mineral that helps with carbohydrate metabolism and is a cofactor in a number of enzymes important in energy production and antioxidant defenses.