Physico-chemical and functional characteristics of flour of Southwestern Ethiopia aerial and tuber yam (Dioscorea) species processed under different drying techniques

The aim of this study was to investigate the physico-chemical and functional characteristics of flour of South-western Ethiopia aerial and tuber yam (Dioscorea) species processed using different drying techniques. Results from the analysis of yam flours revealed that the moisture content, ash, fat, crude fiber, crude protein and carbohydrate values varies in the range of 1.45-6.82%, 2.05-3.94%, 0.13-0.88%, 1.91-3.71%, 4.25-8.72% and 82.08-91.09%, respectively. The mineral contents of yam flours expressed in 100 g dry weight for Na, P, K, Ca, Mg, Fe, Cu, and Zn were 14.08-24.06, 86.26-143.12, 626.66-1487.40, 17.33-88.03, 32.91-84.60, 1.10-7.31, 0.25-1.15, 0.50-1.20, respectively. The contents were significantly (p < 0.05) different between the yam flours. The mean concentration of Pb ranged from 0.004 to 0.058, while Cr, Ni and Co were not detected in the analyzed samples. Freeze dried yam flour had highest lightness (L*) than oven and sun dried flour. All yam flours had lower water activity ranging from 0.23 to 0.51. Aerial yam showed significantly (p < 0.05) higher values of oil ab-sorption (1.94 g/g) and water absorption (2.78 g/g) capacities than the tuber yam species. In conclusion, this study showed that aerial and tuber yam species could serve as potential alternative sources for nutritious food formulation.