Influence of roasting of shea kernels on their fat content and some quality characteristics of shea butter

Abstract

In shea production zones in Sub-Saharan Africa, shea butter is mostly produced by women using traditional methods. Improvement of their practices would allow them to obtain better monetary returns for their activities. Roasting of crushed shea kernels is a processing step that has a major influence on the quantity and quality of extracted shea butter. Using a central composite face-centered design (CCFD), the effect of roasting, specifically roasting time and temperature was investigated. Both factors influenced fat content (44-53% dw) of the crushed kernels; colour characteristics and free fatty acid (FFA) content (0.5-3%) of the butter. In shea butter from differently roasted kernels, 58 volatile compounds were identified, of which 11 were quantitatively dominant, against 27 compounds in butter from unroasted kernels. The ideal practice according to the CCFD model is roasting at 171 ºC for 15 min, which resulted in a fat content of 49% dw of the kernels, a butter yield of 32%, a FFA of 1.2% of the butter, and a peroxide value of 3.2 meq O₂/kg. This optimum roasting time is appreciably shorter than the current practice, suggesting that the use of firewood during traditional processing can be reduced.