ADOPTION OF THE REFRACTANCE WINDOW DRYING TECHNOLOGY IN THE DRYING OF FRUITS AND VEGETABLES IN UGANDA

Farmers in Africa produce a variety of fruits and vegetables with unique nutritional and functional properties that are highly valuable on the international market. The nutritional and functional properties can only be preserved with the use of appropriate drying technologies. Open sun drying and solar drying that are most often used in Uganda require long drying time hence resulting in significant loss of flavor compounds, nutrients, bioactive compounds, and discoloration. With Refractance Window (RW), the fruits and vegetables are conveyed and dried over a bed of hot water using a mylar belt. The dryer therefore offers mechanical simplicity and relatively high drying speed. The advantages of the RW dryer over the conventional method creates an edge for its future development. However, available RW dryers are of very high capacities and cost making them unsuitable for the small-scale processors. In this study, a relatively low capacity (14 - 18 kg/hr of raw material) RW dryer was designed, fabricated, tested and assessed for potential adoption by the processors/farmers.  It was noted that potential for adoption is largely constrained by high operation costs associated with electricity bills, and dryer capacity. The results from the survey indicated that market purchasing power of farmers lay between UGX. 1-6 million (USD 270 – 1625). This means that some processors could opt for small sized machines as well as machines with alternative energy sources such as biomass. Therefore, this study suggests the need for the design of medium-capacity RW drying technologies, which can use both electrical power and biomass. This will increase penetration of the technology to places without an on-grid electric connection  hence catering for the higher small to the medium-size enterprise market, individual farmers, and cooperative groups.