Researchers at a Dutch university claim to have developed a model that predicts how cheese will change when a force is applied to it. The new model will help to predict how cheese is damaged during the packaging or transportation processes.
Anna Rzepiela from Wageningen University in Holland simulated the influence of shearing and tensional forces on the structure of cheese as part of a study funded by the Netherlands Organisation for Scientific Research. Dairy products are subjected to various forces during the production process, packaging phase and the transport phase. The researchers claim these forces modify the characteristics of the product and that the new model describes these processes more accurately.
Cheese is described by the researchers as "a so-called particulate gel, a system of particles that form a weakly-bound network in a liquid environment". Cheese consists of long strands of casein and whey proteins in an environment of whey. Whey is the thin, sweet fluid that remains once the curds have been separated from the milk. The long strands are bound together and form a strong network.
When cheese is pulled apart, the bonds between the particles are broken and the structure of the cheese changes. The model previously used by the researchers assumed that a force applied to the surface of the cheese penetrated directly to deep inside the cheese. However, Rzepiela's model only includes the surface forces. It is the tensions in the network that then transmit the forces further.
The research team says that this model is a better approximation of the real situation. According to the report, the chemist simulated an experiment in which the cheese is clamped between two parallel plates that slide backwards and forwards along the cheese surfaces. The quicker the plates move the greater the deformation, and thus the greater the damage to the cheese.
The old model always predicted the same structural changes, independent of the number of bonds between the strands and the location of these, say the researchers. However they say experiments have shown that the nature and location of the damage was dependent on the structure of the particulate network. As such they feel that the new model can better predict these differences.
Eventually the researchers say they would like to simulate the combined effect of all of these forces on the cheese. They believe that it would then be possible, for example, to describe what happens to cheese when it is chewed.
For further information please contact Anna Rzepiela, Mathematics and Statistical Methods Group, Wageningen University, Holland.