Development of a millet dehulling machine

Abstract

Efficient post-harvest handling practices are important in grain processing. Post-harvest handling of crops includes a combination of several unit operations. Among those processes, dehulling is crucial for many cereal grains as it facilitates the removal of the fibrous outer husk layers. Consumption of cereal grains in their natural form would not be as palatable without dehulling. Millet dehulling for human consumption is done traditionally by mortar and pestle, however, this is laborious and tiresome due to their small size and the unavailability of suitable processing equipment. Dehulling practices can be made simpler and more efficient by adopting and developing appropriate processing technology. The primary objective of this study was set to develop a simple and efficient hand operated, table-top millet dehuller that works under a simple shearing principle by passing grains in between a pair of rubber rollers, this could reduce processing drudgery. The machine was designed, fabricated and tested with the dehulling efficiency assessed by passing (1-3 consecutive passes) the whole grains in different rubber roller spacing (0.20, 0.1, and 0.0 mm). In Uganda, finger millet is the commonly grown and was the only one tested though its efficiency was found to be low. This does not kill the innovation but rather address it in a more appropriate way. Following the results obtained from the project work, the following recommendations were made; New rubber rollers of 80-90 durometer hardness should be used instead of the 45-60 durometer hardness used. Unfortunately, they were not readily available on the market.