Wheat and Flour Testing Methods - WHEATFLOURBOOK.ORG

Rapid Visco Analyzer
Method
1. A sample of 3.5 grams of flour is mixed with 25 milliliters
of water to form a slurry.
2. The rapid visco analyzer stirs the slurry as it is heated
from 60 to 95 degrees Celsius in 6 minutes.
3. The maximum viscosity (peak viscosity) is recorded as a
curve by the rapid visco analyzer.
Results
• The rapid visco analyzer indicates starch viscosity by
measuring the resistance of a flour and water slurry to
the stirring action of a paddle.
• When the slurry is heated, the starch granules swell and
make the slurry thicker.
• A thicker slurry has more resistance to the paddle during
stirring and has a higher peak viscosity.
• The highest point during the heating cycle is the peak
viscosity.
• Rapid visco analyzer results include peak viscosity and
are expressed in rapid visco units (RVU).
• A viscosity curve is shown on the computer monitor in
the photo on page 48.
Why is this important?
The rapid visco analyzer test measures flour starch properties.
For Asian noodle products, flour of medium to high peak
viscosity is preferred because it gives noodles better texture
characteristics.*
The rapid visco analyzer can also be used to determine the
stirring number, which is related to sprout damage. A stirring
n Viscosity analysis
n Measures flour starch
properties
Rapid visco analyzer.
number test is performed to measure enzyme activity that
results from sprout damage (alpha amylase enzyme activity).
Sprouting in wheat results in flour that produces sticky
dough that can cause problems during processing. Sproutdamaged
flour also produces products with poor color and
weak texture.**
*Adapted from RVA-4 Series Operation Manual, Newport Scientific Pty. Ltd. 1995.
**Adapted from Method 22-08, Approved Methods of the American Association of
Cereal Chemists, 10th Edition. 2000. St. Paul, MN.
Wheat and Flour Testing Methods: A Guide to Understanding Wheat and Flour Quality: Version 2