Aqueous enzymatic oil extraction from Irvingia gabonensis seed kernels

The objective of this study was to extract the fat from Irvingia gabonensis kernels without using organic solvent but by using the enzyme aqueous oil extraction process. The aqueous dispersion of kernel flour of bush mango was treated with a protease (Alcalase®), a pectinase (Pectinex®) and a mixture of cell wall-degrading enzymes (Viscozyme®) before centrifugation. The yield of oil extracted was calculated in comparison with the chemical extraction method using hexane as solvent. A central composite experimental design was used for the determination of optimized conditions. The results showed that aqueous extraction without enzyme allows recovering 27.4% of the kernel oil. When Alcalase, Pectinex and Viscozyme were added separately, the oil yields were 35.0, 42.2 and 68.0%, respectively. Optimized conditions for Viscozyme resulted in a model of oil yield with a high coefficient of determination (r² = 0.94). These conditions were the following: kernel-to-water ratio 0.11-0.19, concentration of enzyme 1.4-2.0%, and time of incubation 14-18 h. Confirmation of the model led to 83.0% oil yield after treatment of the kernel flour at a kernel-to-water ratio of 0.16, using 2% Viscozyme for 18 h. Under the same conditions, followed by addition of 1% Alcalase for 2 h, the yield was 90.0%.