Viscosity of butter or margarine

USE

The viscosity of butter and margarine is extremely high. Force measurements can be used for these tests using a texture analyzer. Flow properties can also be measured using a viscometer or rheometer. The Brookfield RST-SST (Soft Solids Tester) can measure flow properties with a test of less than 60 seconds.

TEST EQUIPMENT

Instrument: RST-SST Rheometer

Geometries: VT-10-5 (10mm long by 5mm diameter) and VT-20-20 (20mm long by 20mm diameter)

Test: Controlled Shear Rate (CSR) Performance Test:

Start: 0.5 RPM

End: 0.5 RPM

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

Readings: 30 to 60 measurement points depending on the duration of the test

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

RESULTS

FIG. 1 represents the shear stress as a function of time for 4 different samples. The flow value is described as the maximum shear stress value (ie, ~ 12,000 Pa for the sample labeled "spread" or ~ 95,000 Pa for the sample labeled "Butter") . The test detects large differences between samples.

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

1. The combination of yield value and modulus correlates with the “spreadability” of butter.

2. The test is performed at refrigeration temperatures where consumers use the product.

3. The test is quick; in all four tests, the execution time was less than 30 seconds.

4. The SST is a very rugged instrument, able to withstand constant use in a busy quality control laboratory with very little service.