Establishment and Verification of the Thermodynamic Models for Hotpot Meatballs and Meat Slices

As a traditional Chinese cuisine, hotpot is popular all over the world. Hotpot meat is often presented in the form of meat-slices and meatballs. In daily life, people observe the discoloration and up-floating to judge whether the meatball is well cooked. Experiments have confirmed that such methods lack scientific basis and pose threat to food safety. Firstly, a thermodynamic model of meatballs heating in boiling water is constructed. The theoretical calculation is established and solved by MATLAB and Ansys Discovery Live. The effect of change of meatball diameter and hotpot heating power on the unsteady-state temperature field of meatballs is obtained, concluding that the heating power barely affects the heating process of meatballs. Secondly, the thermodynamic model of meatballs is verified through experiments. Two types of meatballs made of beef with diameters of 30mm and 35mm respectively are used as the experimental objects. A commonly-used household induction heater and a hotpot are used as the heating devices. Several K-type armored thermocouples and an electronic thermometer are used as temperature measuring and data collecting devices. Regarding the difference on meatball diameters and heating powers, multiple experiments are operated. The experimental data graphs are drawn by Excel and MATLAB. The experimental results and the theoretical calculations fit well. The heat transfer coefficient between meat and boiling water is estimated accordingly. A similar thermodynamic model of meat slices is constructed and solved by analytical method. MATLAB is used to draw the temperature curve of the heating process. However, the cooking time calculated by the theoretical model is apparently longer than the actual cooking time. The convective mass transfer phenomenon is further introduced to better describe the heating process of meat slices. Through theoretical derivation, it is found that the rate of mass transfer is related to the surface area to volume ratio of meat. Hence, the heating process of meat slices, compared to that of meatballs, is more significantly affected by mass transfer phenomenon. The conclusions of this paper can provide guidance on eating hotpot food safely.