Losses in sweet potato quality at harvest and during the post-harvest handling in the Mwanza Region of Tanzania

A preliminary survey of the sweet potato marketing chain, from the farm to the market, indicated that substantial loses in quality can occur at all stages. Sacks, containing between 107 and 114 kg of sweet potatoes took between 16 and 23 hours to reach the market. After leaving the farm, they were transported by bicycle, trolley, canoe, ship and light commercial vehicle. Assessment of the sweet potatoes, immediately after harvesting, indicated that approximately 20% to 35% of the sweet potatoes had minor cuts, 14% to 28% had breaks, 19% to 60% had signs of minor skinning, 13% to 59% had skin weevil and 1% to 4% burrowing weevil damage. After transport from the farm to the market, the level of damage in freshly harvested sweet potatoes increased such that 100% of the sweet potatoes had skinning damage, most severely, and 38% to 56% had breaks. Transport had little impact on the proportion of sweet potatoes with cuts or weevil damage. Shrivelled sweet potatoes were less susceptible to damage. The presence of rots, however, led to the sweet potatoes receiving a nominal market value. Handling of the sacks was monitored by visual observations and by shock, temperature and humidity measurements recorded by an 'electronic sweet potato', designed and assembled at NRI, which was inserted into the centre of the sacks. The most severe handling (shocks above 20g) occurred during loading and unloading from the ship, at the customs station of the port and at the markets and appeared to be associated with the occurrence of major breaks. The temperature (220C to 340C) in the sacks was optimum for curing although the very high humidity (greater than 95%) might lead to the occurrence of rots. Further studies will investigate seasonal variations along with other methods of transport to suggest practical and economic recommendations on improved transport and handling practices and direct future research

The use of needs assessment methodologies to focus technical interventions in root and tuber crop post-harvest systems: a case study to improve the marketing and post-harvest handling of cassava entering Dar es Salaam, Tanzania

The accurate targeting of research and technology transfer strategies within root and tuber crops post-harvest systems is essential to ensure that developmental funds within national programmes are used to maximum advantage. Needs assessment studies have important roles to play in initially defining problem areas. Such procedures must be cost effective and generate genuine information quickly and efficiently. This paper describes the use of an urban demand/needs assessment strategy to define the problems evident in the marketing of fresh cassava roots in Oar es Salaam, Tanzania. By examining secondary data and collecting primary information from key participants in the marketing chain, the principal constraints and sources of cassava wastage within the system were identified as were opportunities for possible technical interventions. As a result of these assessments, a more detailed case study was undertaken to quantify the losses of cassava within the system and, thereafter, an adaptive technology transfer programme was initiated to test, adapt and later disseminate elements of the low cost ambient storage technology derived from protocols developed by the Centro Internacional de Agricultura Tropical (CIAT) and the Natural Resources Institute (NRI). Observations made suggest that the adoption of the ambient storage techniques will help reduce financial losses (both physical and financial) to the benefit of producers, marketing agents and consumers