ORIGINAL PAPER Effect of Cooking on Moisture Sorption Isotherms of Sheanut (Vitellaria paradoxa Gaertn.) Kernels: Evidence from Light and Scanning Electron Microscopy Divine Nde Bup & Charles Fon Abi & Gilles Bernard Nkouam & Dzudie Tenin & César Kapseu & Clergé Tchiegang & Zéphirin Mouloungui Received: 15 November 2011 / Accepted: 10 July 2012 / Published online: 22 July 2012 # Springer Science+Business Media, LLC 2012 Abstract 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 steadi- ly with increase in temperature within the water activity range 0.10–0.8 a w but increased rapidly with increase in temperature above 0.8 a w resulting in the overlap of isotherms for all sorption processes. This crossing over of isotherms was at- tributed 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 microsco- py 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. Keywords Cooking . Sheanut kernels . Sorption isotherms . Microscopy . Water activity Introduction Cameroon harbours an important number of multi-purpose tree species, many of which have potential to be exploited at a commercial level. Some of them have played a very important role in the past to feed indigenous populations as snacks, major foods as well as in medicines. With in- creasing interest in research on the improvement of under- exploited food crops with potential commercial value (Haq 2000), the importance of these species are being gradually understood. There are now increased efforts to domesticate some of these species, thus necessitating further research on them. Some of these underexploited crops include Canarium schweinfurthii, Dacrodys edulis, Ricinodendron heudelotii and Vitellaria paradoxa. In addition to the medicinal value of its leaves, bark and roots, Vitellaria is highly appreciated for its oil, contained in its kernels and usually referred to as shea butter. This oil is used in cosmetics, margarine and chocolate D. N. Bup : G. B. Nkouam Higher Institute of the Sahel, University of Maroua, P.O. Box 46, Maroua, Cameroon C. F. Abi Department of Chemistry, Higher Teachers Training College, University of Yaounde 1, P.O. Box 47, Yaounde, Cameroon D. N. Bup (*) : D. Tenin : C. Kapseu Department of Process Engineering, ENSAI, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon e-mail: bupdiv@yahoo.fr C. Tchiegang Department of Food Science and Nutrition, ENSAI, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon Z. Mouloungui Université de Toulouse-UMR 1010, Laboratoire de Chimie Agro-Industrielle, ENSIACET, INP, INRA, 4 allée Emile Monso, BP 74233, 31432 Toulouse Cedex 4, France Food Bioprocess Technol (2013) 6:1897–1906 DOI 10.1007/s11947-012-0935-1