the desired particle size has been achieved. The product is then mixed, and its viscosity profile can be fine-tuned. KEY MANUFACTURING PARAMETERS Given the influence of the production process and machinery on the outcome of identical recipes, it is worth digging deeper into the production parameters that demand close attention in order to achieve chocolate of the right quality. On the refining side of things, the smaller the desired particle size, the higher total fat the chocolate matrix demands. While this may not, at first, seem entirely logical, breaking any particle into, for example, four smaller fragments doubles its surface area. And each fragment’s surface needs to be covered in fat before the rest of the fat in the matrix can create distance between the particles. Then there are the conching considerations. Forming the chocolate’s final viscosity profile is highly dependent on the conching machine used and the way it is operated. Gathering useful data on this parameter requires a modern viscometer, as well as a suitable measuring geometry and a water bath able to hold the sample at a constant temperature. There are other important factors, too, in achieving a successful outcome. For example, the more intensive dry conching and shear applied, the lower the viscosity profile. There are process temperature limits, too, due to different types of chocolates and raw materials. And finally, the more volatiles that can be evaporated during the conching stage, the lower viscosity profile that can be achieved. Figure 1: Example of ‘Normal’ Molding Profile When adding inclusions to a chocolate recipe, the chocolate’s viscosity profile requires adjustment. On the one hand, a more liquid viscosity profile is required. On the other, manufacturers must avoid the feet formation that often accompanies such a profile when placed on a drying surface. A viscosity profile measures three production-related shear rates that will inform us of the result we can expect during tablet molding, hollow figure spinning and enrobing applications where blowing is applied. A ‘normal’ molding profile, that is to say, one with a normal viscosity profile that generally works without problems for solid molding of standard tablets, resembles that depicted in Figure 1. How does chocolate actually behave under different production situations at different speeds? By taking the chocolate through various viscosities, we learn what it can handle. Can it, for example, be used for producing Easter eggs in a spinning mold? Does it fall short for blowing applications by not having sufficient enrobing viscosity? Can it handle the extreme speeds of spraying? PROCESSABILITY To get to the bottom of this, it is useful to work with a flow curve method that generates the ‘Casson’ yield value and plastic viscosity. The Casson model describes what we might term the ‘processability’ of chocolate. THE CHALLENGE OF INCLUSIONS Chocolate inclusions span everything from coffee beans or fragments, to jellies, extruded corn or rice, dried fruits, cookies, to other types of chocolate or confections. 3
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