Enzyme-assisted aqueous extraction of fat from kernels of the shea tree, Butyrospermum parkii

Abstract

Chemical characteristics of kernels of the shea tree (Butyrospermum parkii) from Ghana were determined in order to design and evaluate studies on a traditional enzyme-assisted fat extraction of the kernels. The effectiveness of a number of cellular degrading enzymes in assisting the shea fat extraction were also tested by treating meals of the kernels with one or more of these enzymes before extraction and comparing the yield with control extractions. Proximate composition of the kernel on dry-matter basis was: total lipids, 59.04%; crude fat, 54.85; protein, 7.81%; total carbohydrates, 34.77%; ash, 2.57%. Starch content was 7.59%; hemicellulose, 10.84%; cellulose, 5.95%; and pectic substances, 2.93%. Total fiber content was 20.35%. The fat extracted by the Soxhlet method was pale-yellow in color and solid at room temperatures. Its physicochemical characteristics were: melting range, 34-36°C; iodine value, 58.53; saponification value, 180.37; and unsaponifiable matter content, 7.48%. The predominant fatty acids were: palmitic (3.55%), stearic (44.44%), oleic (42.41%), linoleic (5.88%) and linolenic (1.66%) acids. The enzyme-assisted extraction tests showed increases in extraction yield when the shea kernel meals were treated with the enzyme(s) before extraction. An increase of about 20% was realized when a protease and an enzyme with both cellulase and hemicellulase activities were used together. These observations confirmed the fact that the shea kernel is a rich source of fat. They also indicate the possibility of improving shea kernel extraction processes by pretreating the kernel meal with cell structure-degrading enzymes. © 1994 AOCS Press.