Advances in Yield stress Measurements for Chocolate

Chocolate (a cocoa dispersion), can be defined as a concentrated suspension made up of solid particles, such as sugar, cocoa powder, milk powder, etc., dispersed in a Newtonian liquid, generally cocoa butter. The rheological properties of this matrix are largely influenced by type and quantity of ingredients and processing techniques. During chocolate manufacturing, mixtures of sugar, cocoa and fat are heated, cooled, pressurized and refined. These steps not only affect particle size reduction, but also break agglomerates and distribute lipid and lecithin-coated particles throughout the continuous phase, thus considerably modifying the microstructure and so the yield stress of final chocolate products. The interactions between the suspended particles and the continuous phase provide information about the existing network and consequently can be associated with the properties and characteristics of the final dispersions. Since the macroscopic properties of chocolate products are strongly determined by their microstructure, the evaluation and study of the latter is very important, such as the application of adequate rheological models, to deeply understand the chocolate yield stress characteristics.