Study On Cooking Heat Transfer And Vacuum Cooling Characteristics Of Prepared Vegetable Pork Loin

With the development of The Times,prepared dishes gradually emerged and became popular with the public.The process of getting prepared food into the hands of customers is complicated.The heat transfer and vacuum cooling process of cooking make better preparation for freezing and defrosting of prefabricated vegetables,which is an essential step to ensure the quality of prefabricated vegetables.There are few researches on this field in the past literature,so this paper chooses two processes of cooking heat transfer and vacuum cooling for simulation and experimental research.Analysis of the changes inside the food during the heat treatment process shows that the pork will undergo oxidation reaction,and the spatial structure of proteins in the meat will change from the original relatively tight state to the state of loose and extended.It provides a basis for the subsequent analysis.Numerical simulation of heat transfer in cooking:CFD is selected as the simulation software to improve the previous mathematical model of heat transfer/mass transfer,and check and correct the previous model parameters.The changes of central temperature and water content of food in oil were analyzed.When the temperature reaches the boiling point,water evaporates and dissipates heat.Other energy is transferred to the inside of the food through the heat transfer mechanism,and the central temperature inside the food gradually rises.During the heating process,the surface water of the meat sample evaporates and loses.Because the maturity value(M value)of granular food changes faster,less water migrates to the surface of the central sample when it reaches a specific maturity value.The effects of different oil temperatures on central temperature and water content of food were analyzed.It was found that the higher the oil temperature,the faster the temperature reached the temperature of water evaporation inside the pork.Different ripening values at the same temperature will result in different water distribution in food.The higher the ripeness value,the lower the water content in the food,and the water loss on the surface of pork loin is much higher than that in the center of pork loin.Cooking heat transfer experiment:with pork loin as raw material,it is heated in a constant temperature oil bath of 120℃,140℃ and 160℃.It is found that the simulation can well predict the change of temperature and moisture of pork loin in cooking heat transfer.Therefore,the simulation can be applied to the heat transfer process of pork loin cooking,which provides a foundation for future research.Numerical simulation of food vacuum cooling:On the basis of numerical simulation of vacuum environment,the low-pressure evaporation model of porous food vacuum cooling process was designed in advance,and the unsteady process simulation of vacuum food cooling process was completed by CFD software.On this basis,the possible reasons for the difference between the simulated value and the experimental value are analyzed,and the basic law of vacuum cooling process is put forward:during the cooling process,the temperature decreases gradually from the food center.The temperature gradient is greatest from the surface to the center.Finally,the mass loss and temperature distribution during the cooling process are analyzed.It is concluded that the mass loss is caused by the internal environment and the external environment.Moreover,this paper also studied the temperature changes of foods with different porosity,and found that the higher the porosity,the faster the temperature of the food drops.The lower the ambient temperature is,the faster the center temperature of cooked meat reaches 15 ℃.Food vacuum cooling experiment The cooked pork loin was taken as the research object.The ambient temperatures were-15℃,-25℃ and-35℃ respectively,and the center temperature of cooked pork reached 15℃ after cooling,and the vacuum cooling experiment was carried out.After the experiment,the simulated values were compared with the experimental values,and the verification results showed that the model could accurately predict the temperature distribution inside the meat products.The simulation can be applied to the vacuum cooling process of pork,which provides a foundation for future research.