Measure the Pleasure: Particle Size Analysis of Chocolate Powder

In chocolate manufacturing, controlling the particle size of the different components allows the manufacturer to both increase quality and reduce production costs. Here we demonstrate the ability of the PSA to perform sugar, milk powder and chocolate powder measurements. To highlight the broadness of instrument’s measuring range, we also performed particle size measurements on a much bulkier agglomerated chocolate powder.

Chocolate manufacturing starts with the grinding of the cocoa beans to a semi-solid paste called chocolate liquor. This paste then gets pressed to separate the cocoa butter from the solid fraction, the cocoa powder. In order to give the chocolate its pleasing melting texture, cocoa butter needs to be added in excess to the cocoa liquor - hence the high price tag of the butter. The mixture is then milled together with other powdered ingredients such as sugar and milk, a lengthy process known as conching that is crucial to the development of the chocolate’s flavor and texture.

Particle size affects the production process and final properties of chocolate in many ways. For instance, the viscosities of chocolate increases as the particles become finer. On the one hand, cocoa liquor needs to be milled down to fine particles to allow for as much cocoa butter as possible to be released. On the other hand, a large proportion of very small particles will increase the total surface area, meaning that much more of the (expensive) cocoa butter will be needed to coat the particles. By optimizing particle size distribution (PSD), the manufacturer can also reduce the amount of viscosity modifiers needed in the chocolate. Another way to influence quality is to reduce the size of sugar, milk, and cocoa particles to sizes smaller than about 30 μm, as larger particles feel gritty in the mouth. In conclusion, a narrow particle size distribution (PSD) is desirable to preserve the taste and mouthfeel of chocolate from the negative influence of larger particles, and to prevent the smallest particles from impairing its flow properties.

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