We have been studying the supercritical fluid extraction of cocoa butter from cocoa powder, which is the residual cake that is obtained after defatting toasted cocoa beans by mechanical expression. Samples of cocoa powder containing 12 wt% of cocoa butter were subjected to extraction with supercritical CO_2 at temperatures from 35 to 50°C, and pressures from 9.7 to 34.5 MPa in a lab-scale apparatus. For each experiment we determined the variation of the extraction yield with time, and obtained a fatty-acid profile of different samples of the extracted cocoa butter. Our results show that it is possible to obtain cocoa powders greatly reduced in their fat content. In a typical extraction two cocoa butters with different fatty acid profiles were obtained. One that is richer in light fatty acids was obtained initially in each extraction experiment up to an extraction yield of cocoa butter in the order of 90 wt%, an another one richer in the heavier fatty acids at larger extraction yields. A new model for correlating the extraction dynamics was proposed. The model contains two adjustable parameters and represented the experimental information with an average relative deviation of 5.9%. Our results indicate that the production of cocoa butters with different properties (e.g., melting point) aimed for different applications is feasible using supercritical fluids technology.
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