Viscometry Lab.pdf
Viscometry Lab.pdf
Viscometry Lab.pdf
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FDST 8080 <strong>Lab</strong> 2011<br />
That is, the ratio of viscosity to density is proportional to the time it takes for the liquid to<br />
drop between the marks. The absolute viscosity η can be determined by separately<br />
measuring the fluid density. In some cases it is interesting to determine the “intrinsic”<br />
viscosity of a sample [η], as this can be related to the molecular weight of a dissolved<br />
solute.<br />
Capillary viscometers are of limited use in food systems, as particulate systems can clog<br />
the capillary tube. Also, dependence of viscosity on shear rate or shear history is more<br />
difficult to study. It can be very useful, however for studying clear juices, beverages, or<br />
solutions of food macromolecules such as proteins or carbohydrates.<br />
The time in seconds for the fluid to fall between the two markers is recorded. When<br />
multiplied by the capillary constant k, this gives the kinematic viscosity η/ρ.<br />
V. Juice Viscometer<br />
A variant of the capillary viscometer is the AOAC capillary viscometer for juices (AOAC<br />
37.1.108). It Is more appropriate for fruit nectars and juice products, which may have bits<br />
of pulp and particulates that would clog a precision capillary viscometer.
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