## 3 Results
### Tangential Stress  
In Figure 14, the plots of shear stresses and apparent viscosity for Camembert cheese as a function of the deformation rate can be seen. Figure 14 presents the tangential stresses determined at the three penetration speeds for the 90-degree cone, while Figure 14b shows the apparent viscosity determined for the three geometric configurations of the cone at a speed of 12 mm/min. These graphs illustrate how the tangential stresses and apparent viscosity of Camembert cheese vary with the deformation rate, under different conditions of penetration speed and cone geometry. The overall trend in both graphs shows that as the deformation rate increases, both the stress and viscosity decrease, which is characteristic of shear-thinning materials like Camembert cheese. The differences between the curves reflect how the cheese's response is influenced by the speed of penetration and the geometry of the cone used in the tests. The results obtained in all these types of experiments are easy to explain only when performed at small deformations in the so-called linear region [45]. In this region, the ratio between stress and deformation depends only on time; thus, it is independent of the level of stress and deformation. When larger deformations are applied, the ratio changes and the material may even yield and/or fracture, making the explanation more difficult [38]. For a quantitative comparison of results, a size-independent measure of deformation  
Figure 14: Variation of shear stresses and apparent viscosity for Camembert cheese as a function of the deformation rate: (**a**) shear stresses; (**b**) apparent viscosity. must be defined. Usually, deformation is considered, defined as the relative deformation concerning the initial dimensions as the initial distance between the considered points approaches zero [46]. The presence of a non-slip wall condition is an important prerequisite in accurately measuring constant shear viscosity. In the case of Mozzarella-like cheeses in a melted state, the liquid fat on the surface of the cheese begins to lubricate the wall [19; 47]. This lubrication violates the classical non-slip boundary condition, leading to erroneous viscosity data. When the cheese sample heats up due to the heat transfer caused by friction at the contact surface between the cone and the product, it becomes more fluid [48]. As the temperature increases, hydrogen bonds decrease while electrostatic repulsion increases, leading to the relaxation of bonds between proteins and a shift towards a more liquid-like behavior. In general, to stabilize cream cheeses, an additional amount of carrageenan with pectin is added [49], which will lead to the formation of new bonds between carrageenan, pectin, and the milk protein matrix. As the temperature in the cheese maturation chamber decreases, inducing helix formation, carrageenan begins to form a network and interact with the protein matrix [50]. Pectin will bind water, which can amplify the interaction between the helical form of carrageenan and proteins. Conversely, the formation of more helical bonds is possible due to homogenization, which reduces the size of protein clusters. In this way, an extremely compact and strong gelatinous network can form, and the observed jump in shear stress is caused by the need to break the well-bound network [39]. The plot presented in Figure 15 shows the variation of the apparent viscosity (\(\eta_{\text{a}}\)) of Roquefort cheese as a function of the shear rate (\(\dot{\gamma}\)):  
The data series in the graph with blue points represents the apparent viscosity of the sample for testing with a conical penetrometer with a 9-degree angle. The red points represent the apparent viscosity for the test with a conical penetrometer with a 19-degree angle, and the green points represent the measured values for the test with a cone with a 90-degree angle. The general trend observed for all three cone geometries is that the apparent viscosity decreases as the shear rate increases.