Research Progress in Simultaneous Heat and Mass Transfer of Fruits and Vegetables During Precooling

Abstract

The weight loss and spoilage of post-harvest fruits and vegetables (FVS) occur as a result of physiological and biological processes, the rates of which are influenced primarily by product temperature. In order to maintain the freshness of FVS and reduce losses, it is necessary to cool the product as soon as possible after harvest. Precooling is considered such an effective technique because it quickly removes field heat from FVS, thereby preventing deterioration and senescence. With the increasing demand for fresh FVS, the optimization of precooling technology has received extensive attention, especially the research on its basic principle, that is, the heat and mass transfer (HMT) between FVS and the precooling environment. Therefore, this paper reviews the advantages and disadvantages of several main precooling techniques, their HMT processes, the research methods and detection techniques of HMT, and the simulation and application based on numerical technology. Precooling techniques include room cooling, forced-air cooling, hydrocooling, and vacuum cooling. These advanced detection techniques for HMT include magnetic resonance imaging, particle image velocimetry, infrared thermography, nuclear magnetic resonance, bioelectric impedance analysis, dilatometry, thermogravimetric analysis, and X-ray CT. HMT research mainly adopts porous media method, direct numerical simulation, cell growth simulation. Their applications focus on computational fluid dynamics and the lattice Boltzmann method. Furthermore, this paper highlights the application of the computer field in FVS precooling and provides perspectives on the directions for future research.