Chinese Cooking Key Heat Transfer Law Based On Maturity Value Theory

Chinese cooking is the primary processing method of Chinese table food.The process is complex and large in scale,which has a great impact on macroeconomics and national nutrition and health.The rapid development of the automation and industrialization of the culinary industry is extremely incompatible with the backward status of basic culinary research,and fundamental research is urgently needed.Heat transfer issues are the focus.Among them,the fluid-particle surface heat transfer coefficient(h_fp)is one of the important parameters to quantitatively describe the convective heat transfer rate.It is a key process parameter in the cooking process,affecting the center maturity value(Mc value)and surface overheat value(Os value).Temperature-dependent quality kinetic parameters are important in cooking quality control,huohou control and model optimization.In this paper,the h_fp of typical steaming,boiling,frying,stir frying and decoct is measured and analyzed by time temperature integrator(TTIs)combined with heat/mass transfer model,and the are mainly between 550?1365 W/(m²·?).For the process of boiling,steaming,deepfry,stir-frying,and decoct,the h_fp value was825?1275 W/(m²·?),750?1050 W/(m²·?),550?875 W/(m²·?),840?1375W/(m²·?),1425 W/(m²·?),respectively.At the same time,the kinetic parameters such as the maturity time and surface overheat value of each typical cooking were compared with the maturity value of 0.5 min.Oil frying usually has the characteristics of the short process,intense stirring and transient state.Due to vigorous stirring,the food particles move rapidly,and it is difficult to measure the temperature distribution of food particles and the fluid-to-particle surface heat transfer coefficients(h_fp).In this paper,a predictive model was built for h_fp by combining dimensional analysis with numerical simulation.The specific research steps were as follows:(1)the factors affecting h_fp in the process of oil frying were analyzed.Based on the principle of dimensional analysis,four dimensionless numbers(hfpl/?),lv?/?,Cpf?/?,Tf/100)and the dimensionless prediction formula for constructing h_fp were derived;(2)h_fp was calculated by COMSOL and Matlab software based on the thermal/mass transfer mathematical model of porous media and combined with the actual measurement of the center-time-temperature of the food particles;(3)according to the dimensionless prediction constructed in step 1 and combined with the calculated value of h_fp in step2,the prediction model between each dimensionless quantity was fitted by multivariate regression analysis in SPSS;(4)the residual dimension analysis model was used to modify the established dimensionless prediction model;(5)the accuracy of the model was verified by five sets of verification set data,and the average relative error was 2.79%.Based on the above results,the dimensionless prediction formula of h_fp was finally obtained:Nu=10^-4.09Re^0.876Pr^3.206(T_f/100)^4.18,R²=0.973.The predicted value of the theoretical model had a well consistent with the calculated value of the measured data.The research indicated that dimensional analysis combined with numerical simulation has advantages of good reliability and wide applicability on oil frying process h_fp predict,which can meet the needs of food processing and cuisine engineering.For the first time,the concept of thermal accumulation was made for cooking coke paste.The heat accumulation was described from the aspects of water content,hardness,shear force and color.The kinetic parameters required during the thermal accumulation process were identified.The changes of L^*and b^*belong to the first-order reaction kinetics model,while the changes of water content and shear force belong to the zero-order reaction kinetics model.The Ea of four indicators are 85.19k J/mol and 55.62 k J/mol,55.61 k J/mol and 51.67 k J/mol,z values are 50?,54.73?,55.43?and 58.55?,respectively.Meanwhile,the overheat value was simulated as the thermal accumulation index,and combined with the human sensory test,gained the z value of the overheating of the pork loin that human can sensor is 99?,and the O_s,max(z=99?,reference temperature 110?)is 5.86 min.It can be see that the range of two z value was different,which is worthy of further research.Above all,the study mainly used the heat transfer theory and kinetics of the maturity value theory focuses on several surface heat transfer issues during the cooking process,such as fluid-particle surface heat transfer coefficient(h_fp)and thermal accumulation phenomenon.Finally,the h_fp that based on the TTIs for different typical cooking,the dimensionless prediction model for fring h_fp,and the kinetic parameters of thermal accumulation process was well obtained.