Physics About Heat and Mass Transfer During Power Ultrasound-Enhanced Green Food Processing

Power ultrasound, as an emerging technology, was applied to improve the efficiency, shorten process time, alleviate the quality loss, reduce the resource consumption (i.e., energy and solvent), and promote the green recovery in many food processes. These improvements are closely related with physical enhancement of heat and mass transfer by ultrasound. This work focused on the ultrasonic intensification of heat and mass transfer in various food processes, particularly solvent extraction of food components, purification of food components by adsorption/desorption, and food drying. Computer-aided modeling enables the visualization of heat and mass transfer behavior as well as the study of cavitation characteristics during ultrasound-assisted processing, using mathematic models. The efficiencies of food extraction, adsorption/desorption, and drying were all improved using power ultrasound due to the enhancement of heat and mass transfer based on mechanical and cavitation effects. Together with experimental methods, physical models consist of partial differential equations based on Newton's, Fick's, and Fourier's law that have been developed to explore the mechanism about heat and mass transfer intensification. Generally, ultrasound can improve the key parameters relating to heat and mass transfer for enhancing process efficiency and reducing process time. In addition, the cavitation characterizations, including bubble lifespan, bubble size, and bubble numbers during ultrasound-assisted food processing, can also be studied by some physicochemical models. Overall, the application of numerical simulations showed great promise for advancing the understanding of ultrasound-enhanced food processes, guiding process optimization, and overcoming challenges in scaling up from lab-scale experiments to full-scale industrial applications.