Abstract

Different methods of processing yams have the potential of affecting their retention of micronutrients such as iron, zinc and magnesium. The present study investigated the effects of frying, roasting and sun-drying of yams on the concentrations of Fe, Zn and Mg. The concentrations of Fe in the three controlled (raw and unprocessed) yam varieties ranged between 71-82 mg/kg; Zn between 45-46 mg/kg and Mg between 322-371 mg/kg. Across the three treatments, statistically significant (P < 0.05) reductions were observed in the concentrations of Fe, Zn and Mg when the samples were roasted, sun-dried or fried. The only exception was in the fried white yam (FW) where the reduction in the concentration of Fe was statistically not significant (P > 0.05). In real terms, the percent reduction of Fe in the roasted samples was approximately 40% in all the yam varieties. In the same vein, Zn reduction was between 53-73% (white and yellow yams respectively). Mg loss was greater (61.4%) in the roasted yellow yam variety. Statistically significant (P < 0.05) inter-varietal variations were observed when the roasted, fried and sun-dried samples were compared in relation to the levels of Fe, Zn and Mg in the three yam varieties.