Plasticization and texturization of pasta filata cheese – multiscale process analysis, thermo-rheological characterization, and new approach for continuous extrusion

Pasta filata cheese, like mozzarella, kashkaval, or provolone have a specific anisotropic, fibrous texture which is formed in the unique process step scalding-kneading. Traditionally the scalding-kneading is performed by mixing curd with hot water in a cooker-stretcher until the curd is plasticized. The aim of this thesis was to develop a continuous scalding-kneading process based on a single screw extruder, without the use of added water. Therefore the process and the material properties of curd for pasta filata cheese were analyzed. Curd for pasta filata cheese with different pH and composition were characterized with thermo-rheological methods like small angle oscillatory shear temperature sweep, capillary rheometry, and creep recovery test to determine gel-sol transition, shear viscosity, shear stress dependent behavior and retardation times. The effect of compression and relaxation on the structure was characterized with a small batch system and confocal laser scanning microscopy. Also the effect of temperature and stretchwater composition on yield was studied at bench top scale. With the knowledge obtained in this study a continuous single screw extrusion technology for scalding-kneading of pasta filata cheese was built up, without using stretchwater. It was shown that there are temperature, stress, and time limits which are relevant for the processing of pasta filata cheese.