![]() ![]() ![]() Furthermore, viscosity should not be perceived as an absolute value, but rather a function of external factors such as temperature, shear and pressure, all of which affect viscosity, and thus, the technological and organoleptic properties of a food product. This property is highly dependent on the intrinsic characteristics of a material such as molecular composition, solute concentration, structural organization and density. In practical terms, a fluid with a higher viscosity would flow more slowly and appear thicker than a fluid with lower viscosity (Figure 1). For a more in-depth understanding of these phenomena and its implications, additional reading is recommended. However, the majority of fluids do not behave this way, being called non-Newtonian, and different considerations are required to measure their viscosity. This is only valid for Newtonian fluids, where at a certain temperature, the viscosity would remain constant as a function of changes in shear rate (e.g., water). The shear stress is the force per area needed to move a laminar layer of fluid, whereas the shear rate is the relation of speed between two laminar layers of fluid. Therefore, viscosity is defined as the internal friction of a fluid, or in other words, its capacity to resist flow.Ĭonsidering a fluid as a number of laminar layers, the formula describing viscosity is straightforward, being represented in centipois (cP) or Pascal seconds (Pa s): When a force or stress is applied to a fluid, it flows, resulting in internal friction that resists the flow. ![]()
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