Abstract:Different quick-freezing methods have different effects on the temperature drop rate, uniformity and quality of fish meat after thawing, so that the selection of the best quick-freezing method has become one of the main ways to improve the quick-freezing efficiency of fish and maintain the quality of fish meat in the industry. Taking tilapia as an example, combined with 3D scanning inverse modeling and computational fluid dynamics numerical simulation and other technologies, the temporal and spatial distribution laws of tilapia temperature under cold-air quick-freezing, sodium chloride and calcium chloride quick-freezing were intuitively obtained. The accuracy and reliability of the simulation results were verified by the comparison of the simulation results. The effect of different quick-freezing methods on the freezing rate, uniformity and water loss of tilapia was comprehensively compared and analyzed, and the optimal quick-freezing method was determined and an optimal design scheme was proposed. The results showed that the maximum deviation between the simulated temperature and the measured temperature was 1.81℃, the maximum root mean square error and the average absolute percentage error were 1.017℃ and 18.9%, respectively. When the temperature of tilapia dropped to -15℃ during freezing process, the maximum relative deviation between the simulated freezing time and the measured value was only 6.89%. Secondly, the freezing rate of tilapia under the two immersion quick-freezing methods of sodium chloride and calcium chloride was basically the same. Compared with the cold-air quick-freezing method, the freezing time was reduced by about 73%, and the freezing uniformity was improved by about 10 to 40 times. Thirdly, the water loss rate of tilapia after thawing under the two immersion quickfreezing methods was only 3.89% and 3.92%, which were 10.37% and 9.68% lower than those of the cold-air quick-freezing method, respectively. Finally, an optimization scheme of sodium chloride hydrofluidization freezing method was proposed. By comprehensively considering the freezing rate, uniformity and energy consumption, the optimal flow rate was determined to be 2.5m/s. The freezing efficiency was optimal when the fish was placed vertically, and the fish was placed horizontally with its back to the entrance.