Phase behavior and extended phase scheme of static cocoa butter investigated with real-time X-ray powder diffraction

A complete isothermal phase-transition scheme of cocoa butter under static conditions is presented, based on time-resolved X-ray powder diffraction experiments. In contrast to what is known from literature, not only beta V, but also beta VI can be obtained directly through transformation from beta'. Another remarkable result is that beta' exists as a phase range rather than as two separate phases. Within this beta' phase range no isothermal phase transitions have been observed. More detailed information concerning the observed cocoa butter polymorphs was obtained by determination of melting ranges, using time-resolved X-ray powder diffraction. Also standard X-ray powder diffraction patterns of the gamma, the alpha, and the two beta phases and parts of the beta' phase range have been recorded. The observed phase behavior of cocoa butter has been explained based on the concept of individual crystallite phase behavior of cocoa butter.