Effect of Deep-Fat Frying on the Vitamins, Proximate and Mineral Contents of Cocoyam

Abstract

Colocasia esculenta (Cocoyam) is cultivated primarily for its edible tubers. The objective of this work was to study the effects of frying on the vitamins, proximate and mineral contents of cocoyam by using three different oils (canola oil, soya oil and vegetable oil). It was also oven-dried which served as the control sample. The HPLC method was used for the vitamin analysis. The vitamin A content of dried cocoyam was the highest (0.275±0.007 mg gG1) but it was greatly reduced in cocoyam fried with canola oil (0.034±0.048 mg gG1) and totally lost in cocoyam fried with soya oil and vegetable oil. Vitamins D, E and K were totally lost in cocoyam fried with canola oil. The results of the mineral analysis revealed that the dried cocoyam sample contained high amounts of sodium (257.500±2.121 mg gG1),potassium (128.350±0.354 mg gG1) and calcium (320.050±0.000 mg gG1) and there was a general decrease in the values of most minerals especially sodium,magnesium and iron. The dried cocoyam samples had high levels of protein (26.64%), carbohydrate (44.91%), moisture content (13.2%), ash content (2.14%),crude fibre (11.27%) but low level of lipid in comparison with the fried samples.Cocoyam fried with vegetable oil had the lowest level of protein (22.41%) and carbohydrate (16.8%) but the highest level of lipid (23.03%) and moisture content (27%). The results show that oven-drying retains most of the nutrients of cocoyam compared to deep-fat frying and that each oil sample has its own disadvantage.