Paper Title
Application of The Hot-Extrusion Process in Mozzarella Cheese Production -Influence of Process Parameters on Product Quality

Abstract
The influence of screw speed and configuration on the texture and color as well as the protein, fat and water content of extruded mozzarella cheese was investigated. The screw speed range of 50 - 800rpm was used as a process parameter and four different screw configurations at maximum barrel temperatures of 90°C were used in the experiments. In the findings, firmness and protein content of the extruded mozzarella cheese decreased as the screw speed of the extruder increased. On the other hand, a significant (p<0.05) increase was observed in the fat content of the extruded cheese. The screw speed of 300 rpm achieved the best texture properties and significantly less firmness compared to the others. Furthermore, the significant effects on firmness were also observed by the screw configuration of the mixing element compared to kneading. Subsequently, the combined elements of mixing and kneading also revealed a stronger effects than an individual screw element. The color intensities of both the inner and outer layers of the extruded cheese were measured; The L* values of the inner layer were significant (p<0.05) and the b* values approached a yellowish hue compared to the market products, however the screw configurations had no influence on the color intensity of the extruded mozzarella cheese. The findings clarify that the production of mozzarella cheese as well as the rheological and nutritional quality can be controlled by the hot extrusion process. Keywords - Firmness, Mozzarella cheese, Nutritional value, Screw configuration, Screw speed, The hot-extrusion.