Flourpedia.com - The wheat and
flour basic tests described in this section are standardized testing procedures
commonly used for quality control purposes. Results from these basic tests have a
direct relationship to finished product quality.
Wheat and flour specifications are communications between buyers and sellers. These specifications are requirements for particular wheat and flour characteristics. To meet these specifications, wheat and flour quality testing is necessary.
Specifications for moisture content, ash content, protein content, and falling
number are determined with basic tests. Physical tests included in this blog
are conducted to determine flour color and wheat kernel characteristics
specified by wheat processors.
The laboratory milling basic test is used to evaluate
the milling performance of wheat and to produce flour for other laboratory
tests. Wheat and flour specifications often require specialized basic testing to
determine how flour will perform during processing.
Several basic tests evaluate
dough and gluten strength properties. The farinograph and mixograph tests
measure the resistance of dough to mixing. The extensograph test measures the
resistance of dough to stretching.
The alveograph test measures the resistance
of a bubble of dough to expansion. The wet gluten test measures the amount of
gluten protein in flour. The starch properties of flour are measured by the amylograph
and the rapid visco analyzer tests.
Section One is intended to provide
information on wheat and flour quality basic tests used by the wheat industry
worldwide to promote an orderly marketplace.
Moisture Content in Wheat and Flour
Moisture
content is one of basic tests for wheat and flour. Moisture content test usually divided in two method : moisture content test by oven and rapid moisture analyzer. In this chapter we will study about how to test Moisture content in wheat and flour using oven (conventional test).
Moisture content determined by heating a flour or ground wheat. Sample in an air oven
and comparing the weight of the sample before and after heating. The amount of
weight loss is the moisture content. Moisture content results are expressed as
a percentage. An example of a wheat moisture content is 12%.
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| Measures Moisture Content |
Determining
moisture content is an essential first step in analyzing wheat or flour quality
since this data is used for other tests. Flour millers adjust the moisture in
wheat to a standard level before milling. Moisture content of 14% is commonly
used as a conversion factor for other basic tests in which the results are affected
by moisture content.
Moisture is also an indicator of grain storability. Wheat
or flour with high moisture content (over 14.5%) attracts mold, bacteria, and
insects, all of which cause deterioration during storage.Wheat or flour with
low moisture content is more stable during storage.
Moisture content can be an
indicator of profitability in milling. Flour is sold by weight, grain is bought
by weight, and water is added to reach the standard moisture level before
milling. The more water added, the more weight and profitability gained from
the wheat.
Wheat with too low moisture, however, may require special equipment
or processes before milling to reach the standard moisture level. Other methods
of determining moisture content are used in the industry. For example, Federal
Grain Inspection Service (FGIS) uses the GAC 2100 to measure moisture content
of whole wheat kernels.
Ash Content in Wheat and Flour
Ash content
is one of basic tests for wheat and flour. Ash content determined by high temperature incineration in an electric muffle furnace. When
a sample is incinerated in an ash oven, the high temperature drives out the
moisture and burns away all the organic materials (starch, protein, and oil),
leaving only the ash.
The residue (ash) is composed of the non-combustible,
inorganic minerals that are concentrated in the bran layer. Ash content results
for wheat or flour ash are expressed as a percentage of the initial sample
weight; for example, wheat ash of 1.58% or flour ash of 0.52%. Wheat or flour
ash is usually expressed on a common moisture basis of 14%.
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| Measures Mineral (Ash) Content |
The ash
content in wheat and flour has significance for milling. Millers need to know
the overall mineral content of the wheat to achieve desired or specified ash
levels in flour. Since ash is primarily concentrated in the bran, ash content
in flour is an indication of the yield that can be expected during milling.
Ash
content also indicates milling performance by indirectly revealing the amount
of bran contamination in flour. Ash in flour can
affect color, imparting a darker color to finished products. Some specialty
products requiring particularly white flour call for low ash content while
other products, such as whole wheat flour, have a high ash content.
Protein Content in Wheat and Flour
Protein
content is one of basic tests for wheat and flour. Protein content determined through high temperature combustion in a protein
analyzer.
Since protein is the major wheat compound that contains nitrogen, the
protein content can be determined by measuring the amount of nitrogen released
during burning.
Protein content results are expressed as a percentage of the
total sample weight; for example, 10% protein content on 12% moisture basis for
wheat or 8.5% on 14% moisture basis for flour.
 |
| Measures Protein Content |
Protein
content is a key specification for wheat and flour purchasers since it is
related to many processing properties, such as water absorption and gluten
strength. Protein content can also be related to finished product attributes,
such as texture and appearance.
Low protein content is desired for crisp or
tender products, such as snacks or cakes. High protein content is desired for
products with chewy texture, such as pan bread and hearth bread.
Bakers use
protein content results to anticipate water absorption and dough development
time for processes and products, because higher protein content usually
requires more water and a longer mixing time to achieve optimum dough
consistency.
Combustion Nitrogen Analysis (CNA) is often used to develop calibrations
for other protein methods, such as Near Infrared Transmittance (NIRT) or Near
Infrared Reflectance (NIRR).
Falling Number in Wheat and Flour
Falling Number is one of basic test for wheat and flour. The falling
number instrument analyzes viscosity by measuring the resistance of a flour and
water paste to a falling stirrer. F
alling number results are recorded as an
index of enzyme activity in a wheat or flour sample and the results are
expressed in time as seconds.
A high falling number (for example, above 300
seconds) indicates minimal enzyme activity and sound quality wheat or flour. A
low falling number (for example, below 250 seconds) indicates substantial
enzyme activity and sprout-damaged wheat or flour.
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| Measures The Effects of Sprout Damage |
The level of enzyme activity in wheat and flour measured by the Falling
Number Test affects product quality. Yeast in bread dough, for example,
requires sugars to develop properly and therefore needs some level of enzyme
activity in the dough.
Too much enzyme activity, however, means that too much
sugar and too little starch are present. Since starch provides the supporting structure
of bread, too much activity results in sticky dough during processing and poor
texture in the finished product.
If the falling number is too high, enzymes can be added to the flour in various ways to
compensate. If the falling number is too low, enzymes cannot be removed from
the flour or wheat, which results in a serious problem that makes the flour
unusable.
Conclution
Conclution
The Basic test for wheat and flour are Moisture content, Ash Content, Protein content and Falling Number.
We hope this blog (Basic test for wheat and flour) can provide useful information about moisture content, ash content, protein content, falling number and other basic test for wheat and flour (such as : Farinograph, Mixograph, Extensograph, Alveograph, Wet Gluten Test, amylograph, and rapid visco analyzer).
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