Models for FFA-removal and changes in phase behavior of cocoa butter by packed column steam refining

Cocoa butter was steam refined in a packed column at temperatures ranging between 170 °C and 260 °C, with 1-3% steam injected, in order to verify the impact of refining conditions on the crystallization properties. Even at 260 °C, no significant changes in the TAG-distribution of the cocoa butter could be detected. The observed FFA-removal during packed column stripping can be well predicted by the simplified Bailey equation, however, for very high vapor pressures, an extended Bailey equation can be considered. Based on crystallization experiments with SAXS/WAXD and DSC, it has been suggested that the removal of FFA invokes marginally higher crystallization of both the meta-stable polymorphs (α and β′) of cocoa butter at 20 °C. The amounts of solid fat at equilibrium and the induction time of the isothermal crystallization showed a strong linear correlation with the residual acidity. Upon tempering at 24 °C, the generally observed crystal structures evolved from feathery spherulites to larger platelet crystals as more FFA was been removed by the refining, but this could not be unambiguously related to the polymorphic behavior.