Chemical Compositions of Three Economic Tuber Crops Grown In South East, Nigeria

Abstract

Yam (Dioscorea spp) are known for their climbing properties, twining stems which coils readily around a stake and exhibiting glaborous leaves. Via root system, they are perennial but are usually grown as annual crops. Yam is economically important because it serves a staple food for millions of people in Africa, as well as Nigeria. There is limited information on nutrients composition of Nigerian foods. As a result, nutrients intake from Nigerian foods is in most cases estimates using foreign food composition tables. This research determined and compared proximate compositions, phytochemicals, minerals and antinutrients in white yam (Dioscorea rotundata), water yam (Dioscorea alata) and Cocoyam (Xanthosoma sagittifolium) purchased at Nkwo Market, Amaekpu Ohafia, Abia State, Nigeria. The result revealed moisture and protein contents were higher in cocoyam (10.19%, 8.86%) compared to white yam (10.08%, 2.48%) and water yam (10.11%, 5.07%) respectively. Carbohydrate content is rich in the samples (78.42%, 76.17% and 73.29%) for white yam, water yam and cocoyam respectively. The results of protein, fibre and ash were also similar. Cocoyam had higher mineral contents compared to white yam and water yam. The tuber crops do not contain toxic levels of antinutrients. Little amounts of phytochemicals are also present, and the proximate composition of the tuber crops varied significantly. The result justifies that the three tuber crops (white yam, water yam and cocoyam) indicating some useful amount of phytochemicals confirms their therapeutic values. Furthermore, it is evident that the presence of proteins, minerals, vitamins, fats and fibre at moderate concentration, implies that yam can serve as a good source of food to man. Finally, the antinurients (phytate, oxalate and cyanide) present in the analyzed yam samples were moderate, implying that the yam is safe for consumption.