Low temperature heating
Measures moisture content
M o i s t u r e C o n t e n t
Flora Engelmann, Laboratory Technician
1.
A small sample of flour or ground wheat (2–3 grams) is weighed and
placed in a moisture dish.
2.
The sample is heated at 130oC in an air oven for 1 hour.
3.
The sample is cooled to room temperature and the residue is weighed.
Moisture content is 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%.
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 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.