Thermodynamics of meat proteins

We describe the water activity of meat, being a mixture of proteins, salts and water, by the Free-Volume-Flory–Huggins (FVFH) theory augmented with the equation. Earlier, the FVFH theory is successfully applied to describe the thermodynamics to glucose homopolymers like starch, dextrans and maltodextrins. We have estimated parameter values from sorption isotherms of unsalted, lean meat products and model proteins like elastin and gelatin. These parameter values are quite similar to those found for glucose homopolymers. Moist meat products are also characterized with a water holding capacity, which we can describe with the Flory–Rehner theory. Subsequently, we have been able to predict very accurately the sorption isotherms of salted meat products and gelatin gels. Hence, the thermodynamics of foods can be described without the use of the controversial concept of bound/unfreezable water. Comparison of FVFH theory combined with Flory–Rehner theory to concentrated systems shows that the theory contains terms that are double counting for elastic effects – which makes us conclude that the validity of the Flory–Rehner theory is restricted to the (semi)-dilute regime. A complete thermodynamic description is proposed via mathematical matching of the FVFH and Flory–Rehner theory.