Abstract: Zizania latifolia has delicious taste and high nutrition value, but is perishable with a short shelf life due to the water content of over 90%. In order to extend the shelf life, a mathematical model to describe heat and mass transfer in cylindrical pieces of Zizania latifolia during vacuum cooling was developed taking into consideration both transient heat transfer and mass conservation, and using computational fluid dynamics, simulation and prediction of heat and mass transfer in Zizania latifolia were conducted. Pressure variations inside the vacuum chamber, material mass variations, and temperature distribution were also simulated and compared with the experimental data. The results indicated that the simulation results agreed with the experimental data. The deviation between simulated and experimental values for pressure, mass loss and average temperature difference between the inside and the outside was 7.4%, less than 8% and only 3.7%, respectively. The model proved to be useful to predict the change of heat and mass transfer in cylindrical pieces of vegetables during vacuum cooling, which will provide useful references to study the water migration characteristics of cylindrical pieces of vegetables under vacuum environment and improve the vacuum cooling process in the food industry.

Key words: vacuum precooling, cylindrical pieces of Zizania latifolia, heat and mass transfer, computational fluid dynamics simulation