Speaker
Description
Understanding fouling formation and preventing its consequences are crucial in the dairy industry to improve the efficiency of unit operations and the quality of the products. To date, most of the literature associated dairy fouling development with the heat-induced denaturation of whey proteins, which leads to their aggregation and progressive adsorption onto surfaces. Nevertheless, this hypothesis has a major flaw: fouling also occurs at temperatures below the denaturation threshold (≈ 70°C). This is the case, for example, in falling-film evaporators, used in the dairy industry for vacuum concentration prior to spray drying. These considerations highlight the need to explore the impact of other process parameters, besides temperature, to fully understand fouling. However, shedding light on fouling dynamics is extremely challenging with the current experimental methods, given the size and structure of dairy equipment. Therefore, a real-time observation of the phenomenon is still lacking, especially at the micron scale.
To address these crucial open questions, we employed an original rheofluidic approach to investigate the role of shear rate in the formation of dairy deposits. Our outcomes showed how, at sub-denaturation temperatures, shear not only increases the amount of whey protein deposits but also promotes their structural complexity. Encouraged by these results, we also performed direct observations of the fouling growth in microfluidic devices replicating the typical environmental and flow conditions of falling-film evaporators. These observations enabled the discrimination between the simultaneous and competitive mechanisms governing protein aggregation in the bulk solution and those occurring at the surface. This preliminary study also allowed for a first characterization of the kinetics of deposit growth.
The miniaturization approach therefore proves to be effective in providing a better overview of the microscopic mechanisms leading to fouling propagation and of the factors influencing this phenomenon. This represents a first step toward the development of more comprehensive predictive models and innovative mitigation strategies.