Material properties that describe how substances — and especially microorganisms — respond to applied heat. Thermophysical data such as conductivity, specific heat, and diffusivity govern how foods heat and cool, while microbial heat resistance determines whether a process kills. A food-safety twist: bacteria like Listeria can acquire extra heat resistance after sublethal warming, by producing heat-shock proteins, so processes need safety margins beyond laboratory D-values. Engineers and microbiologists combine thermophysical properties with thermal-death kinetics to design heating regimes that stay reliably lethal across the variability of real foods and microbes.