Determination of mass transfer parameters during the cooking process of pork tenderloin and their effects on Chinese cuisine

Abstract: Chinese cuisine with a rich history has a wide range of complex and various techniques. Among them, the oil stir-frying is characterized by a significant short, intense dynamic process. Numerical simulation is also required to explore the process mechanism of cooking quality formation. Mathematical models are crucial to simulate the food heat treatment, and then optimize and control the process. The reliability of these models can rely mainly on the accuracy of the parameters. The unsteady-state transfer of water mass includes the convective mass transfer, due to the macroscopic movement of fluid on the solid-liquid boundary during oil stir-frying. The parameter of this process is the surface mass transfer coefficient (h_m), represented by the rate of mass transfer between the fluid and the surface of the food particles pmoisture diffusion coefficient (D_eff) can indicate the speed of component diffusion in the medium. Specifically, D_eff was a material transfer property that was determined by the random movement of internal water molecules after molecular diffusion and mass transfer. The hm and surface heat transfer coefficient between particle fluid and particle (h_fp) between the particle and fluid can be referred to as the surface transfer coefficient. These parameters are closely related to the specific process. This study aims to investigate the effects of controllable operations and key process parameters on oil stir-frying cooking, in order to enhance the reliability and accuracy of numerical simulation. The h_m and D_eff of moisture were determined, according to the dimensionless analytical solution of moisture content during the oil stir-frying of pork tenderloin. A systematic investigation was made to analyze the effects of preheated oil temperature and specific surface area (Ω) on hm and D_eff. Subsequently, a comparison was made on the effects of h_m and h_fp on cooking maturity. The maturity value theory was proposed using the mathematical model of heat and mass transfer in the oil stir-frying. The hm values ranged from 5.927 × 10^-6 to 2.481 × 10^-5 m/s, which were slightly higher than those reported in similar deep-frying studies. The D_eff values and activation energy (E_a) ranged from 6.281 × 10^-9 to 4.148 × 10^-8 m²/s and 24.2 to 30.6 kJ/mol, respectively. Furthermore, the preheating oil temperature and Ω had a significant effect on h_m and D_eff (P < 0.05). Higher preheated oil temperatures led to greater hm and D_eff values, while the larger Ω values resulted in larger hm and smaller D_eff values. Additionally, the hm value shared a minor impact on the cooking process, whereas the h_fp was a crucial process parameter to control the cooking. The key parameters hm and D_eff can be used to numerically simulate the heat and mass transfer in oil stir-frying. There were some effects of preheating oil and knife handling on h_m and D_eff during oil stir-frying. Additionally, the mechanisms of h_m and h_fp in the heat mass transfer can also be clarified during oil stir-frying.