Variation of the Physical Properties of Sheanut (Vitellaria Paradoxa Gaertn.) Kernels during Convective Drying

摘要

The effect of moisture content and drying temperature of Vitellaria paradoxa Gaertn kernelsnon some of its physical properties was investigated. The kernels which were harvested at anmoisture content of about 60% (wet basis) and hence prone to high post harvest losses from twonecological zones of Cameroon (Bangoua in West province and Tchabal in Adamawa province)nwere dried in a forced convection dryer at 40oC, for 6, 20, 48, 72 and 96 hours to give moisturencontents ranging from 10 to 60% wet basis. Ten trees from each of the zones were carefully selectednto serve as sources for the ripe kernel bearing shea fruits that were used as samples for thisnstudy. For each parameter studied, a sample population of 30 kernels selected at random per treenwas used. The results obtained revealed that there was a significant difference in the physical propertiesnof the kernels from different trees irrespective of the locality. The bulk density, true density,nsphericity and porosity varied non-linearly with the moisture content. Kernels with larger massesnshowed a different variation pattern of bulk density and porosity with moisture content comparednto the lighter kernels. The variation of the bulk density, sphericity, porosity of sheanut kernels withnmoisture content and temperature was satisfactorily modelled with empirical equations. The samplesnunderwent considerable shrinkage (up to 35%) during the drying process. Three empiricalnmodels were used to describe the shrinkage behaviour of the kernels and it is proposed that thesenmodels could be incorporated in drying models.