Predicting the Electrorheological Behavior of Milk Chocolate

Electrorheology is the study of the effects of electric fields on the flow properties of fluids. These materials generally exhibit an increase in apparent viscosity and a greater yield stress over an unelectrified sample. The phenomenon requires an electric field and polar particles suspended in an insulating oil. A standard concentric cylinder viscometer, fitted with custom made electrical attachments, was converted into an electrorheometer. This system allowed control of DC voltage (0–450 Volts mm−1), fluid temperature (35C–40.5C), and shear rate (0.022 s−1– 8.744 s−1) while observing the resulting effects on the shear stress. Dimensional analysis was used to study the rheological response of milk chocolate when subjected to electric fields. Dimensionless groups were identified to explain the phenomena, and multiple regression analysis was used to predict the electrorheological flow behavior of milk chocolate. Over the ranges of input variables, the electric field‐induced forces dominated the rheological response over thermal forces, and a prediction equation for apparent viscosity was developed as a function of electric field strength and shear rate. This mathematical expression allows for prediction of milk chocolate rheology in the presence of an electric field.