Xylitol-mediated Diffusion Simulation Of Sodium Chloride Cured Pork Tenderloin And Its Thermodynamic Study

Polyhydroxyalcohol mediated curing has the potential to reduce sodium chloride content and water activity in cured meat products,and is one of the effective ways to process wet cured meat products with low salinity.This study focused on the phenomenon of mass and heat transfer in the process of polyhydroxyalcohol mediated curing,and explored the mechanism of the effect of xylitol-mediated cured tenderloin.The main research results of this article are as follows:（1）The effect of xylitol-mediated curing on the physicochemical properties of pork tenderloin was investigated when the concentration of xylitol was 0%-12%.By measuring shear force,curing absorption rate,cooking loss,water activity,electronic tongue taste value,and texture,it was found that with increasing xylitol concentration,meat tenderness and texture characteristics were improved,while shear force,salting absorption,cooking loss,and water activity were significantly reduced.Through electronic tongue taste value analysis,xylitol can reduce the saltiness value of tenderloin to achieve the goal of low salt curing.In addition,xylitol-mediated curing can also protect the stability of myosin,sarcoplasmic protein,and actin conformational molecules in pork tenderloin,thereby improving the thermal stability of pork tenderloin.（2）The mass transfer kinetic equations for different concentrations of xylitol in the curing process were established,and it was found that the addition of xylitol can reduce the effective diffusion coefficient（De）of sodium chloride（NaCl）during the curing process.Linear time variable model,power function time variable model,and exponential time variable model were used to evaluate the change of NaCl content in the muscle aqueous phase during xylitol-mediated curing of pork tenderloin.Among the three models,power function time variable model was the most suitable mathematical model for predicting the change of NaCl content with time during the curing process（R²>0.9500）.（3）According to the calculation of a power function time-varying model,when 0%,4%,8%,and 12%xylitol-mediated NaCl curing,the De values of NaCl are 1.29×10^-9 m²·s^-1,1.22×10^-9 m²·s^-1,1.2×10^-9 m²·s^-1and 1.15×10^-9 m²·s^-1,respectively,which are highly consistent with the De values measured by the experimental method.Using the tds module embedded in COMSOL Multiphysics for model construction and finite element partitioning,the diffusion process was simulated and the effectiveness of the simulation model was verified.The results showed that the model was reasonable.（4）The static weighing method of saturated solution was used to draw the moisture adsorption isotherm（MSI）during the xylitol-mediated curing process of tenderloin,and the thermodynamic characteristics of tenderloin were studied based on the MSI.The Aw and water content data of pork tenderloin cured with different concentrations of xylitol were measured.Eight common thermodynamic models,such as Peleg,GAB,Halsey,Caurie,Henderson,and BET,were selected,and the data were non-linear fitted using R language.Through precision comparison,Peleg was obtained as the most suitable model for describing the MSI curve of xylitol-mediated curing.By calculating the net equivalent heat of adsorption(q_st),after adding 4%,8%,and 12%xylitol to mediate curing,the q_stvalues of pork tenderloin were increased from 5.06 k J·mol^-1to 5.08 k J·mol^-1、5.20k J·mol^-1 and6.25 k J·mol^-1,respectively.To sum up the research content,the following conclusions are obtained:Xylitol-mediated curing have a positive impact on the physical and chemical properties of pork tenderloin,improve the quality of pork tenderloin,reduce the NaCl content of pork tenderloin,and improve the thermal stability of muscle protein.This article determines the De value of NaCl in the process of xylitol-mediated curing of tenderloin based on Fick’s second law.Through exploring the mass transfer kinetics of NaCl and one-way simulation of NaCl diffusion during the curing process,it is found that adding xylitol can reduce the De value of NaCl,thereby effectively reducing the NaCl content in the cured tenderloin;When the addition amount of xylitol is 0%,4%,8%,and 12%,the one-way model diffusion coefficients of NaCl are 1.29×10^-9 m²·s^-1,1.22×10^-9 m²·s^-1,1.2×10^-9 m²·s^-1 and1.15×10^-9 m²·s^-1,respectively,which are highly consistent with the predicted values obtained by the power function time-varying model.Using COMSOL Multiphysics to construct a one-way model for diffusion simulation,the obtained model has a good correlation with experimental data,and can achieve visual research on NaCl diffusion and distribution during the mediated curing process.At the same time,the water adsorption isotherm of pork loin during xylitol-mediated curing was measured using the water activity preservation theory to explore the changes in thermodynamic parameters of pork loin during xylitol-mediated curing.It was found that the Peleg model was the best model to describe the water adsorption characteristics of xylitol-mediated curing on pork loin.The addition of xylitol increased the q_st of pork loin and was positively correlated with xylitol concentration,indicating that xylitol-mediated curing can improve the storage stability of pork tenderloin,and providing a theoretical basis for the storage and drying of xylitol-mediated curing pork tenderloin.