Crystallization Dynamics of Shear Worked Cocoa Butter

Control of heat and mass transfer conditions during chocolate manufacture is a critical factor influencing product quality and performance. The molecular basis for specific tempering protocols developed by the chocolatiers, and used widely by the food industry, is poorly understood. Here we show that cooling and shear rates applied during cocoa butter crystallization affect the incorporation of specific triacylglycerol (TAG) molecular species onto the surface of growing seed crystals, thus affecting the different structural levels in a cocoa butter crystal network. In this work, the effects of shear work on the different structural levels in cocoa butter are determined. Results from this research show different compositions during the early stages of static crystallization at different cooling rates. In other words, there is selective attachment of TAG species onto growing crystal surfaces, leading to fractional crystallization. With the application of shear, differences between cooling rates became negligible. Shear appears to enhance the formation of mixed crystal in the growing crystals, leading to faster crystallization kinetics, the formation of a higher number of smaller crystals, and a mechanically stronger crystal network.