糖心TV

Chocolate consists of a well-crystallized cocoa butter matrix in which fine cocoa powder and sugar particles are dispersed. The physical properties of the crystalline cocoa butter give chocolate it聮s appreciated characteristics such as gloss, snap and the cooling effect when melting in the mouth. Therefore crystallization is a critical step in making chocolate and confectioneries. Poorly crystallized chocolate may result in the formation of fat bloom, a greyish-white film at the chocolate surface. Also storage under wrong conditions may result in the same. Bloomed chocolate not only looks unattractive but it also has a less attractive feel on the palate. Solid cocoa butter may be found in at least six different crystalline forms. This polymorphism has been studied extensively in the last century. In quality chocolate cocoa butter is crystallised in the so-called β-V form. However, β-VI is the most stable polymorph and it is generally accepted that the transformation from β-V into β-VI causes fat bloom. We tackled the crystallisation of cocoa butter with high-resolution X-ray powder diffraction (XRD), time-resolved XRD, single crystal XRD and Small Angle Scattering, as well at the ESRF with synchrotron radiation as in our laboratory with the highest quality diffraction instruments. A major step to unravel the mechanism of fat bloom was set recently when we solved the crystal structures of both the β-V and β-VI polymorph of cocoa butter. The lecture will explain the mechanism at the molecular level, give representative details of the many experiments we did and their interpretation, show some results of a patented new way of producing chocolate at factory-scale, and let the audience take part in a small chocolate experiment.