Effect of curing treatments on seven key farmers’ yams (Dioscorea spp.) in Ghana

Abstract

Curing of freshly harvested yams (Dioscorea spp.) is a process for wounded yams during harvest to heal. In this work the effectiveness of straw, polypropylene and jute sack on curing of seven key farmers’ yam varieties over a duration of 7, 14 and 21 days was studied. Seven key farmers’ yam varieties identified as Pona, Lariboko, Dente, Mutwumudoo, Serwah belonging to D. rotundata, Matches and Akaba belonging to D. alata were studied under different curing treatments. The percentage weight loss of yam tubers varied among the treatments over curing period. Curing under jute sack showed all yam varieties had weight losses less than 2.0%, within 7 days of curing. Five different varieties had weight loss less than 2.0% except Dente under the straw treatment. Mutwumudoo variety showed the highest water loss (8.4%) for polypropylene sheet and 6.9% for Lariboko in the control treatment. During 7 days curing the control and polypropylene treatment did not support yam curing. After 14 days of curing of tubers, similar tends were observed as in 7 days curing. After 14 days of curing under jute sack, percentage weight loss of the tubers ranges from 2.0% - 3.7%. In the straw treatment, the percentage weight loss ranges between 1.0% - 4.7% in all other varieties except Dente (D. rotundata) (8.2%). Polypropylene sheet treatment showed the highest percentage weight loss in Mutwumudoo variety (18.4%). A similar trend was observed for the yam tubers cured for 21days as percentage weight loss of tubers under jute sacks was 2.5 – 9.8%. Curing temperature and humidity ranged between 27˚C - 40˚C and 87% - 100% rh for yam tubers under the three different treatments of polypropylene, jute and straw. However, the control treatment recorded lower humidity of 60% - 80% rh. Curing material, duration, climatic conditions and yam varieties influenced curing and Serwah variety, which is a D. rotundata is the best bet yam variety to cure under jute sack for 7, 14 and 21 days of curing