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Brookfield AMETEK

Butter and Margarine


Because butter and margarine are normally used at these temperatures, and because the viscosity is extremely high, this has long been a difficult test. While force measurements can be used these tests do not really measure flow properties as well as a viscometer or rheometer. With the introduction of the Brookfield R/S SST (Soft Solids Tester) the flow properties of these foods can now be measured with a test running under 60 seconds.

Test Method

Instrument: R/S+ SST2000 Rheometer

Geometries: V3-10-5 (10 mm long by 5 mm in diameter), V3-20-20 (20 mm long by 20 mm in diameter) vanes

Test: Controlled rate (CSR) yield test, 1 step:

Start: 0.5 RPM

End: 0.5 RPM

Length: 30 seconds to 60 seconds (depending on the sample)

Readings: 30 to 60 depending on step length

Temperature: All samples (and the rheometer vanes) were conditioned in a refrigerator at 4.5°C prior to testing.

* While a particular model/version may be used as an example in this method, any current or past model/version from the same series may also be used. Please consult a sales associate to discuss the most current instrumentation and software available.


The yield value is described as the peak shear stress value (i.e., ~12,000 Pa for the sample labeled “spread”, or ~95,000 Pa for the sample labeled “Butter”). The test sees large differences between the samples.

We also calculate the modulus (slope of the stress/time curve) and again values show significant differences; ranging from 1,168,313 Pa for the butter (the stiffest) to 75,264 Pa for the spread (the loosest).

  1. The combination of yield value and modulus correlate with butter "spreadability"
  2. The test is done at cold temperatures, where consumers are using the product
  3. The test is fast; in all four tests above the total test time was less than 30 seconds
  4. The R/S SST is a very robust instrument, able to withstand constant use in a busy QC lab with very little service

Figure 1