Agriculture Reference
In-Depth Information
characteristics required to meet end-use per-
formance standards. Understanding functional
quality, defi ned as the wheat doing what the pro-
cessor wants it to do for a given end product,
requires information beyond FGIS grades and
grade requirements.
at an understood moisture level. For wheat
sold in the US, protein is expressed as a percent-
age on a 12.0% moisture basis. In Canada, wheat
is sold with protein content quoted as a percent-
age on a 13.5% moisture basis. Others buy and
sell grain and grain products on a dry (0.0%)
basis. Flour buyers often require a quote for
protein content on a 14.0% moisture basis. When
communicating about the level of an attribute in
grain or a grain product sample, establishing the
moisture level at which the attribute is expressed
is critical.
Nongrade factors
Nongrade quality factors often infl uence value
and expected outcomes for the buyer, but they
are not part of the offi cial US grade and grade
requirements. They include moisture, protein,
and ash contents, enzyme activity, physical
dough characteristics, and baking characteristics.
A more technical description of the methodology
and instrumentation used to measure many
of these quality factors is provided in Chapter
20. They are mentioned here in the context
of understanding miller and baker preferences
that
Wheat ash content
Wheat ash content also is expressed as a percent-
age at a given moisture basis. Ash is the mineral
residue present after incinerating a wheat or fl our
sample. The amount of minerals present in a
wheat sample often varies among cultivars and
growing environments. Millers and grain buyers
must understand the amount of minerals present
in a wheat sample, because bakers often specify
the maximum allowable mineral content of
fl our.
Understanding the specifi cation along with the
inherent mineral content of the wheat to be
ground allows the miller to make fi ne adjustments
in mill settings to exclude the outermost layers
of the endosperm, where minerals are more
concentrated. By purchasing wheat with lower
ash content, millers are sometimes able to extend
the extracted percentage of fl our from the wheat
berry. This might be as small as a 0.5% unit
extraction improvement but can add signifi cantly
to the miller's profi t margin.
often
are
expressed
in
purchase
specifi cations.
Moisture content
Moisture content is the amount of water by weight
present in a wheat sample. Too much moisture
can lead to spoilage during storage, and in many
cases, the difference between low wheat moisture
content and fl our moisture allowed by a baker
is equivalent to the miller's profi t margin.
Although wheat is discounted at the fi rst point
of sale (farmer to elevator) when the moisture
level exceeds 13.5%, the reverse is not the
case. Farmers do not receive premiums for low-
moisture wheat, which makes moisture valuable
to millers. The US market treats excessive
moisture as a discount to value but does not
always take into consideration the value of
low moisture.
Kernel weight
Kernel weight of wheat is measured in commer-
cial sectors as the weight (in grams) of 1,000 wheat
kernels, or thousand-kernel weight (TKW). This
value is infl uenced to some degree by wheat size
and density but is less susceptible to some of the
environmental factors that infl uence kernel com-
paction when measuring test weight. Thousand-
kernel weight supplements information provided
Protein content
Protein content is measured by determining the
amount of nitrogen present in the wheat sample,
and with the conversion factor of 5.7, it is
expressed as a percentage of the sample weight
