Physical Test for Wheat and Flour

Flour Color Analysis
Measures Flour Color
Flour color is determined by measuring the whiteness of a flour sample with the Minolta Chroma Meter. Flour color results are reported in terms of 3-dimensional color values based on the following rating scale:
L* value                               whiteness                           100 white
                 0 black

a* value                               positive values                  +60 red color
         negative values                – 60 green color

b* value                              positive values                  +60 yellow color
        negative values                – 60 blue color

The color values of a typical white flour, for example, are:
L* value +92.5 whiteness
a* value –2.4 green color
b* value +6.9 yellow color

Flour color often affects the color of the finished product and is therefore one of many flour specifications required by end-users. Generally speaking, a bright white color flour is more desirable for many products.

Single Kernel Characterization System (SKCS)
Wheat kernel characteristics are analyzed for: kernel weight by load cell, kernel diameter and moisture content by electrical current, and kernel hardness by pressure force. Averages and standard deviations of these parameters are reported as SKCS results in terms of values: kernel weight is expressed in milligrams
(mg); kernel diameter is expressed in millimeters (mm); moisture content is expressed as a percentage; and kernel hardness is expressed as an index of –20 to 120. A graph displaying kernel characteristics is shown on the computer monitor in the photo :
 
Measures Kernel Characteristics
The Single Kernel Characterization System Test evaluates wheat kernel texture characteristics by measuring the weight, electrical current, and force needed to crush the kernels. Kernel characteristics are related to important milling properties, such as conditioning (tempering), roll gap settings, and flour starch damage content.

Buhler Laboratory Flour Mill
Determines flour yield and makes flour for other tests
Wheat samples are milled to evaluate wheat milling properties, including flour extraction and the amount of non-flour components produced, such as bran and shorts. Buhler Laboratory Flour Mill results are expressed as the weight of flour, bran, and shorts. Often, flour extraction is reported as a percentage of flour compared to the total output of other mill products. Flour is produced for other tests.

The Buhler Laboratory Flour Mill Test indicates milling properties on small wheat samples. Commercial flour mills can use to this information to adjust mill settings to adjust flour extraction. See “How Wheat isMilled” diagram below :


Small samples of wheat are milled on the Buhler Laboratory Mill to produce flour. This flour is used to evaluate properties, such as ash and protein content, and in gluten strength tests, such as the farinograph.

Amylograph
The Amylograph Test measures flour starch properties and enzyme activity which results from sprout damage (alpha amylase enzyme activity). Sprouting in wheat, as indicated by high enzyme activity, produces sticky dough that can cause problems during processing and results in products with poor color and weak texture. For Asian noodle products, flour of medium to high peak viscosity is preferred because it gives noodles better texture characteristics. Both the amylograph and the rapid visco analyzer measure starch viscosity properties. The amylograph is more commonly used throughout the world. The RVA uses a smaller sample and takes less time than the amylograph.



The Amylograph Test measures and records the resistance of a heated slurry (a flour and water paste) to the stirring action of pins.
  • Peak Viscosity is the maximum resistance of a heated flour and water slurry to mixing with pins. It is expressed in Bradbender Units (BU).

Sprouted wheat flour has a lower peak viscosity than sound flour.

Rapid Visco Analyzer
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 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. Sprout-damaged flour also produces products with poor color and weak texture.



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