A viscometer is an instrument that measures the viscosity of food products such as dough or batter.

Viscometer

Also known as a viscosimeter


What is a Viscometer?

A viscometer is an instrument that measures the viscosity of liquid, semi-solid and even solid food products. Viscometers are important components of quality assurance laboratories as they are used to obtain information about the flow behavior (rheology) of materials due to changes in processing conditions, formulation, aging (staling), etc.

Viscosity measures the internal friction of a fluid, an indicator of its resistance to flow. It is expressed in centiPoise (cP) or Pascal-sec (Pa-s). Water has a viscosity of 1 cP.

Viscometers are used by manufacturing companies in the production of ketchup, tomato juice, jam, batters, gums, starches, syrups, chocolate, milk concentrates (condensed milk), mayonnaise, fruit pulps, dressings, margarine, molasses, honey, pumpable shortenings. Companies rely on viscosity measuring devices to check product consistency, batch to batch, to always deliver the best product to customers.

Origin

The first viscometers date back more than a hundred years ago. Possibly, the first instrument  for testing the rheological and textural properties of foods was developed by the French researcher Schwedoff in 1889. The instrument was, essentially, a deformation apparatus for studying jellies based on a torsion test which can objectively measure rigidity, viscosity, and relaxation characteristics.1

How does it work?

Viscometers work under several physical principles. Different types of viscometers operate according to their design, the nature of sample (Newtonian and non-Newtonian behavior) and testing conditions. Types of viscometer include rotary viscometer, falling sphere method, u-tube capillary viscometer, Rapid Visco Analyzer (RVA) and viscoamylograph.

Rotary viscometer
It measures the torque (energy or work) required to rotate an immersed cylindrical or disc spindle in a fluid product. Rotary viscometers measure the viscosity of liquids by measuring the resistance of the material to the stirring action of the spindle which is driven by a motor to obtain a certain number of revolutions per unit time.

A rotary viscometer usually uses multiple speed transmission that generates different shear rates, and interchangeable spindles to measure a variety of viscosity ranges, making it a very versatile instrument. This instrument measures viscosity...


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