Thermal mixing via acoustic vibration during continuous flow cooling of viscous food products

Abstract

During conventional continuous flow cooling of viscous foods, laminar flow and low thermal conductivity lead to a wide temperature distribution within the product, resulting in non-uniformity, slow cooling processes and degradation of final food quality. It was hypothesized that continuous flow cooling would be enhanced by equalizing the temperature profile (thermal mixing) during cooling. In this study, a computer-controlled frequency, audio transducer amplifier was used to impose transversal vibration motion on a 180° bend pipe and generate thermal mixing of viscous foods, such as sweet potato puree, banana puree, apple sauce and cheese sauce, at the temperature range of 110–60°C. Applying vibration at the maximum amplifier volume and 20Hz, the resonance frequency of the unit, the initial radial temperature distribution of 3–20°C was reduced to a temperature difference of 0–4°C, for all the food products. Although parameters such as the magnitude of the initial temperature difference and the gel formation at the pipe wall, which occurs during the cooling of these kinds of food materials, need to be controlled better for future applications of this method.