Phase equilibria and physical properties of CO2-saturated cocoa butter mixtures at elevated pressures


Venter, M.J. and Willems, P. and Kareth, S. and Weidner, E. and Kuipers, N.J.M. and Haan, A.B. de (2007) Phase equilibria and physical properties of CO2-saturated cocoa butter mixtures at elevated pressures. Journal of Supercritical Fluids, 41 (2). pp. 195-203. ISSN 0896-8446

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Abstract:The melting point and phase behaviour of cocoa butter under CO2 pressure were observed in a high-pressure view cell. The melting point decreases from 35 to 23 °C at CO2 pressures higher than 5 MPa. A static analytical procedure was used to measure the solubility of CO2 in cocoa butter at 40, 80 and 100 °C and pressures of 2–35 MPa in an autoclave set-up. The density and viscosity of the CO2-saturated cocoa butter was measured simultaneously in this set-up. The experimental procedure was first validated by comparing the data measured for the system CO2/hexadecane with literature data. The highest solubility of CO2 in cocoa butter of 36 wt.% occurs at 40 °C and 35 MPa. The measured solubilities differed from those previously reported in literature. This can be attributed to differences in the cocoa butter used for measurements. The density of CO2-saturated cocoa butter increases with pressure, whereas the viscosity decreases. The Grunberg equation was used to correlate the viscosity of CO2-saturated cocoa butter. The measured data were used to estimate the theoretical gas assisted mechanical expression (GAME) yields. In GAME CO2-saturated cocoa nibs are mechanically expressed. The calculated GAME yields deviate from the experimental ones due to the oversimplification of the mechanism involved in GAME.
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Copyright:© 2007 Elsevier
Science and Technology (TNW)
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