Abstract

Aerial yam is an underutilized food crop that has potential for reducing food insecurity in Sub-Saharan Africa. Two cultivars of aerial yam (Tob2857 and Tob3059) were evaluated for the impact of harvesting period on the on-farm energy, yield, selected engineering properties, and volatiles organic compounds of the bulbils. The average expended energy on the farm at the end of 6, 7 and 8 months harvesting period was found to be 5625.25, 5889.01 and 6162.85 MJ, respectively. The energy input for the three harvesting period depended on the forms of energy and followed the order; fuel energy > labour > yam setting>machine> chemical energies. The bulbils yield increases with increase in harvesting period and Tob2857 was 14.81, 12.70 and 44.56%, respectively higher at 6, 7 and 8 months harvesting period than Tob3059. The geometric mean diameter, sphericity, transverse and longitudinal force at break ranged from 56.88 - 71.78 mm, 0.69 - 0.75, 1125.16 - 1411.74 N and 588.66 - 869.37 N, respectively. Thirty-six different volatiles compounds were found in the yam bulbils, among which acetate derivatives (ethyl acetate, propyl acetate, 2- methyl butyl acetate, isobutyl acetate and isoamyl acetate) were abundant as the key odour-active. The principal components analysis reflected a significant relationship (p<0.05), and the first, second and third PCs elucidated 39.5, 22.4 and 10.8%, respectively of the total variation. Eight months harvesting period with highest geometric mean was related to lowest specific energy.