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The standard static gravimetric method was used to determine moisture sorption isotherms of both raw and cooked sheanut kernels at 40, 50 and 60 °C in the water activity range 0.11-0.96 in order to evaluate the influence of cooking on the moisture sorption capacity of the kernels. Preliminary analysis showed that the kernels lost a significant quantity of its proteins and carbohydrate during the cooking process. Results of analysis of the moisture sorption isotherms revealed that cooked kernels generally had significantly ( p < 0.05) lower equilibrium moisture contents (EMC) than the raw ones for both desorption and adsorption processes. The effect of temperature on the sorption processes as portrayed by the desorption isotherms revealed that EMC decreased steadily with increase in temperature within the water activity range 0.10-0.8 a but increased rapidly with increase in temperature above 0.8 a resulting in the overlap of isotherms for all sorption processes. This crossing over of isotherms was attributed to the dissolution of sugars at higher water activities. The protein matrix in the kernel was observed using light microscopy and was found to have been disorientated after cooking. Studies using light and scanning electron microscopy revealed that the reduced ability of cooked kernels to sorb water could be linked to changes in the structure of the kernels brought about by the cooking of the kernels. It is concluded that cooking had a very significant effect on the amount of water sorbed by sheanut kernels. [ABSTRACT FROM AUTHOR]

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