Thermophysical Properties of Cured and Uncured Beef, Pork, Poultry Meats, and Ready-to-Eat Hams Measured by the...

Thermophysical properties of foods, including thermal conductivity (k), specific heat capacity (Cp), density (ρ), and diffusivity (α), are important parameters not only for predicting the temperature distribution during conductive heating or cooling of solid foods to evaluate the survival of foodborne pathogens but also for determining the energy consumption of processing and preservation equipment. In this study, we measured k, volumetric heat capacity (ρCp), and α for raw ground beef, ground pork, ground turkey, chicken breast (5°C-60°C), cured ground beef and cured ground pork (5°C-70°C), and uncured/cured ready-to-eat (RTE) ham (5°C-80°C) using the transient plane-source (TPS) method. At temperatures above 60°C, protein denaturation and fat melting in raw meats significantly affected the measurement of thermal properties. Cured ground meats maintained stability in texture and moisture-holding potential up to 70°C. However, uncured and cured RTE ham were found to be able to maintain the texture even at 80°C due to other ingredients added. The physical properties of the tested items were found to be either constant or temperature-dependent. In general, the k values are 0.2-0.6 W m^-1°C^-1, ρCp values are 2.0-5.0 MJ m^-3°C^-1 (1 MJ = 10⁶ J), and α [=k/(ρCp)] are 0.5-3.5 × 10^-7 m² s^-1. The results may fill the data gap, which is much needed for thermal processing, especially to estimate the foodborne pathogen lethality. More studies are needed to accurately measure the thermal properties of raw meats affected by protein denaturation and fat melting. This study reported the food thermal conductivity (k), volumetric heat capacity (ρCp), and thermal diffusivity (α) for several raw and cured meats on the markets. These thermal properties may be used to design and optimize a heat-conduction thermal processing for foods to achieve better product quality, operation cost savings, and so forth. With those temperature-dependent parameters available, the thermal inactivation of foodborne pathogens in raw and cured meat products may be predicted/evaluated with better accuracy in heating profiles to further enhance the microbial food safety.