Abstract

Moisture content (MC) loss is a key factor in the deterioration of harvested sweet potato root tubers. Five improved cultivars: CIP4400168, Ex-Igbariam, Tanzania, TIS 8164 and TIS 87/0087 were collected from sweet potato farmers in Jos, propagated; harvested after 4 months; stored for 8 weeks in a barn and were analyzed fortnightly for moisture content (MC) directional loss and dry matter (DM) content from the surface (peel) and different depths (slices) of the circumferences. Fungal biodeteriogens penetration of the samples was also analyzed to determine MC and DM effects on their colonization. The peels before storage highest mean percentage MC ranged between 44 and 54% in-depth (5^th layer) with DM of 56% and 46% respectively. The root tuber CIP 4400168 had the highest peel MC of 43 and 53% in-depth (5^th layer) with DM of 57 and 47% respectively. The MC was low at the peels with less water saturated DM and high within the in-depth layers with more water saturated DM an indication that MC directional loss was towards it. This was the trend in the other cultivars resulting in their significant differences (P ≤ 0.05) in the parameters. A total of 30 biodeteriogens were isolated, Aspergillus niger, A. oryzae, A. terreus, Candida albicans, Rhodotorula sp had 100% occurrence. Mucor pusillus and A. oryzae, were isolated from the peels and all the depths (1-7 layers) with pH range of 3.87 – 6.67. The harvested produce should be processed into secondary products to avoid the effects of MC directional loss which was evident after fortnight storage in the barn.