| Popis: |
A significant number of foods are manufactured in the form of emulsions. A typical example of such a product is mayonnaises, which vary in oil content. However, as a macroemulsion, they are a thermodynamically unstable system. Therefore, the physical instability associated with processes such as flocculation, coalescence and Ostwald ripening leads to separation of the oil and water phases over time. This is especially typical of low-fat mayonnaises. As the oil content in the sauce decreases, it is necessary to add various biopolymers to ensure its stability over time. Predicting physical instability is important for food technology development purposes, and especially for reduced oil systems as the most challenging task in terms of system stabilization. In the first approximation according to the Stoke’s model, the stability of an emulsion is affected by microstructural characteristics such as as the droplet size and the rheological properties of the emulsions. The combination of this approximation with the generalized Casson’s rheological model for structured liquid systems allows us to propose an approach for estimating the rate of emulsion creaming. The parameters used for calculations are determined from rheology and laser diffraction data for mayonnaise samples. The approach is devoid of empirical variables, since all parameters have a physical meaning on the basis of the kinetic model of destruction–recovery of the structural aggregates of the system. Calculations were carried out for a series of commercial mayonnaises (CMs) and developed low-fat mayonnaise (LFM). The results make it possible to evaluate the physical stability of emulsions, as well as the influence of rheological and microstructural characteristics on the texture of the final product during its shelf life. |
