![]() ![]() ![]() In the CGS system, the unit (η) is measured in poise. The SI unit of viscosity coefficient is N sm –2 (newton second per square meter). ![]() Viscosity is expressed in terms of the coefficient of viscosity, ‘η’ (Eta).Laminar flow of a liquid (fluid) through a tube/pipe Hence, a velocity gradient exists across the cross-section of the tube. This is a result of the viscosity of a liquid. When a liquid flows through a tube, the central layer has the highest velocity, whereas the layer along the inner wall in the tube remains stationary.It is also the resistance to the flow of a liquid. Viscosity is defined as the force of friction between the successive layers of a flowing liquid.Strong intermolecular forces obstruct the layers from slipping over one another, resulting in friction between the layers. The subsequent layers slip over one another. Here, the layers of molecules in the immediate contact of the fixed surface remains stationary. Different layers of a liquid flow with different velocities.Viscosity measures the magnitude of internal friction in a liquid or fluid to flow as measured by the force per unit area resisting uniform flow.Liquids (fluids) have a tendency to flow.“Correlation between in-line measurements of tomato ketchup shear viscosity and extensional viscosity.” Journal of Food Engineering 173 (2016): 8-14. Berta, Marco, Johan Wiklund, Reinhardt Kotzé, and Mats Stading.“Re: Viscosity” Received by Katie Jones, 2 Jan. “What Is Viscosity.” Brookfield Ametek, Accessed 12 Jan.Examples of these properties could be color, hardness, boiling point, or freezing point. “Non-Newtonian Flows.” Department of Chemical and Biomolecular Engineering, Clarkson University.(2002). Viscosity in the Chemistry Realm: In the field of chemistry, there are many different physical properties of substances and elements. The obvious advantage is the improved quality in batter consistency and potential cost savings in not reworking out of spec batches.” 4 References “Consequently, some major bakeries have progressed from making benchtop measurements with a rotational viscometer in the QC lab to using an on-line process viscometer which measures continuously as the batter is mixed and processed. ![]() There may also be a correlation between the density of the baked product and the viscosity of the batter. Thicker formulations are more difficult to move and handle in general. Processing the batter effectively in a production operation relates back to the viscosity issue. 5 For example, “the ability to characterize the pseudoplastic behavior of the batter can pay dividends in more ways than one. Understanding viscosity can allow you to determine the best process and equipment needed for commercial production of your product. 5 How Can Viscosity Impact Commercial Production 1 Small variations of processing conditions and raw materials can affect flow behavior and final viscosity. It is important to remember a material’s viscosity is not a single point measurement, but often depends on a number of factors, like time and temperature. Another option is an inline system allowing constant monitoring during production. Samples may be gathered during processing and lab tested by QA staff. Viscosity is measured with Viscometers, Rheometers, or Plastometers. 1 Cream to whipped cream is an example of a rheopectic food.
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