In the treatment of oropharyngeal dysphagia, the link between diagnosis and prescription of thickened liquids that are safe to swallow is not always straightforward. Frequently, the capacity to objectively assess and quantify the rheological properties of diagnostic test fluids and to select “rheologically equivalent” dietary products is missing. Perhaps sometimes the importance of an objective comparison is not fully appreciated because two liquids seem reasonably similar in a subjective comparison (e.g., flow from a spoon). The present study deals with some of these issues. Shear viscosity measurements were used to characterize the flow behavior of videofluoroscopic contrast agents and of thickened fluids prepared with commercial thickening agents. Effects of time and composition of the different fluids were analyzed regarding shear-rate-dependent viscosity. Nearly all materials tested showed a pronounced dependence of viscosity with shear rate (“shear thinning”). Results confirm that it is feasible (but not always straightforward) to “match” the viscosities of diagnostic fluids and thickened beverages if certain precautions are taken. For example, the time required to reach final viscosity levels can be significant for some thickeners, particularly when used with liquids containing contrast agents. It is recommend to use only diagnostic materials and thickening agents for which reliable viscosity data are available.
Food engineering faces the difficult challenge of combining taste, i.e., tailoring texture and rheology of food matrices with the balanced intake of healthy nutrients. In materials science, fiber suspensions and composites have been developed as a versatile and successful approach to tailor rheology while imparting materials with added functionalities. Structures based on such types of physical (micro)fibers are however rare in food production mainly due to a lack of food‐grade materials and processes allowing for the fabrication of fibers with controlled sizes and microstructures. Here, the controlled fabrication of multi‐material microstructured edible fibers is demonstrated using a food compatible process based on preform‐to‐fiber thermal drawing. It is shown that different material systems based on gelatin or casein, with plasticizers such as glycerol, can be thermally drawn into fibers with various geometries and cross‐sectional structures. It is demonstrated that fibers can exhibit tailored mechanical properties post‐drawing, and can encapsulate nutrients to control their release. The versatility of fiber materials is also exploited to demonstrate the fabrication of food‐grade fabrics and scaffolds for food growth. The end results establish a new field in food production that relies on fiber‐based simple and eco‐friendly processes to realize enjoyable yet healthy and nutritious products.
It is well known that the perceived texture and consistency of liquid foods are strong drivers of consumer preference, yet quantification of these parameters is made complicated by the absence of a concise mathematical framework. In this paper, we demonstrate that fractional rheological models, including the fractional Maxwell model (FMM) and the fractional Jeffreys model (FJM), are potential candidates to fill this void as a result of their ability to succinctly and accurately predict the linear and nonlinear viscoelastic response of a range of liquid food solutions. These include a benchmark
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