Thermal and compositional properties of cocoa butter during static crystallization

Studies were conducted using differential scanning calorimetry (DSC) and high performance liquid chromatography (HPLC) to determine the thermal properties and glyceride composition of cocoa butter crystals formed under static conditions. In addition to these studies, visual characterization of the crystallites was obtained with polarized light microscopy (PLM). Crystals were formed under controlled static or motionless conditions at formation temperatures of 26.0, 28.0, 30.0, 32.0 and 33.0 C. Preparatory techniques were developed using laminated polyethylene with plastic hoops in order to grow the crystals for isolation and visual identification by PLM prior to DSC assay. Cocoa butter was also crystallized from liquid oil directly in the DSC pans prior to thermal assay. At each crystal formation temperature (26–33 C), various crystallite types grew, each with varying triglyceride composition (PLiP, POO, PLiS, POP, SOO, SLiS, POS, SOS, SOA). As an example, the ‘feather’ and ‘individual’ crystals formed at 26.0 C exhibited significant increases in SOS and significant decreases in POP compared to the original butter. It was determined that the original amount of SOS significantly increased in the cocoa butter crystallite as the incubation temperature increased from 26–32 C.