Improving the efficacy of cocoa liquor grinding: a parametric approach

This study systematically evaluates the role of operating parameters in controlling cocoa liquor grinding performance in a stirred mill. In chocolate manufacturing, precise particle size control is essential to achieve optimal sensory properties while avoiding overgrinding and unnecessary energy consumption. Experiments were conducted using a 4 l laboratory-scale mill capable of both batch and continuous operation, with a uniquely adjustable orientation angle. Five orientations between horizontal (0 ∘ ) and vertical (90 ∘ ) were evaluated. Vertical operation consistently produced greater particle size reduction under equivalent conditions, whereas horizontal operation generally exhibited lower power demand. Grinding media fill level was found to exert a strong influence on performance: increasing the fill from 65 % to 80 % enabled comparable grinding outcomes at approximately half the power input due to reduced rotational speed requirements. In continuous operation, liquid flow significantly altered grinding behaviour, disrupting the strong correlation between particle size reduction and specific energy observed in batch mode. These results demonstrate that optimal grinding performance arises from a balance between mill orientation, media loading, and flow conditions, and might not be constrained to horizontal or vertical systems.