THE INFLUENCE OF DIFFERENT CALCIUM-SEQUESTERING SALTS ON THE HYDRATION CHARACTERISTICS OF RENNET CASEIN IN A SIMPLE MODEL SYSTEM

Abstract

A wide range of calcium-sequestering salts is available for use in cheese analogues and processed cheese manufacture. The effects of different calcium-sequestering salts, at equimolar concentrations, on the rheological behaviour of rennet casein during hydration in a simple model system were studied. The degree of protein hydration and solubilisation varied with the calcium-sequestering abilities of the salts. Hydration and solubilisation of rennet casein in the weak calcium-sequestering salt, trisodium citrate, was very limited and a dense cheese-like mass formed. In disodium orthophosphate greater hydration to form a curd-like mass of high viscosity index was observed. More effective calcium-sequestering salts such as pentasodium polyphosphate resulted in rapid solubilisation of the protein to give a solution with a low viscosity index, while disodium pyrophosphate and tetrasodium polyphosphate-based dispersions showed intermediate behaviour. The pH of the dispersions also influenced the hydration behaviour of the casein. At the low pH (6.38) of monosodium orthophosphate-based dispersions rennet casein remained as discrete particles, while at the higher pH (>9.0) of trisodium orthophosphate-based dispersions the casein was solubilised. The cation of the calcium-sequestering salt also influenced the hydration behaviour of the rennet casein. The effects of the different salts on the hydration of rennet casein in the model system are discussed in relation to their influence on functional properties such as texture and meltability of cheese analogues and processed cheeses prepared using the salts.