Wheat Grades Wheat grades reflect the physical quality and condition of a sample and thus may indicate the general suitability for milling. The U.S. grade for a sample is determined by measurement of such factors as test weight, damaged kernels, foreign material, shrunken and broken kernels and wheat of other classes and contrasting classes. All numeric factors other than test weight are reported as a percentage by weight of the sample. Grade determining factors include:

Test Weight. A measure of the density of the sample and may be an indicator of milling yield and the general condition of the sample, as problems during growing season or at harvest often reduce test weight.

Damaged Kernels. Kernels which may be undesirable for milling because of disease, insect activity, frost or sprout damage, etc.

Foreign Material. Any material other than wheat that remains after dockage is removed. Because foreign material may not be removed by normal cleaning equipment, it may have an adverse effect on milling and flour quality.

Shrunken and Broken Kernels. Kernels that were insufficiently filled during growing and have a shrunken or shriveled appearance or were broken in handling. Such kernels may reduce milling yield.

Vitreous Kernels. Hard red spring wheat kernels that are uniformly dark and have no spots that appear chalky or soft. In durum, vitreous kernels have a glassy and translucent appearance without any spots that appear chalky.

Total Defects. The sum of damaged kernels, foreign material and shrunken and broken kernels.

Wheat of Other Classes and Wheat of Contrasting Classes.  Wheat classes are specific to end use and if too much of a wheat of another class is found the grade is lowered.  Amounts allowed are much lower for contrasting wheat classes because the end-use is different and the negative influence on end-use performance is greater.

Stones and other non-Wheat Material.  Limits are placed on non-wheat material such as stones, weed seeds, animal filth and any other unknown foreign substances

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Dockage. The percentage by weight of any material easily removed from a wheat sample using the Carter Dockage Tester. Dockage, because it can be removed, should not negatively influence milling quality but may have other economic effects for buyers. Grade factors are determined only after dockage is removed.

Moisture Content. The percentage of water by weight of a sample and is an important indicator of profitability in milling. Flour millers add water to adjust wheat moisture to a standard level before milling. Lower wheat moisture allows more water to be added, increasing the weight of grain to be milled at virtually no cost. Moisture content is also an indicator of grain storability as wheat and flour with low moisture are more stable during storage. Because moisture can be readily added to or physically removed from a sample, other analysis results are often mathematically converted to a standard moisture basis (mb), such as 14%, 12% or dry matter, so results can be compared.

Protein. The percentage of protein by weight in a sample. Protein can be quickly and easily measured and therefore is an important factor in determining the value of wheat since it relates to many processing properties, such as water absorption and gluten strength. Low protein is desired for products such as snacks or cakes. High protein is desired for products such as pan breads, pasta, buns and frozen yeast-raised products.

Ash Content. The percentage of minerals by weight in wheat or flour. In wheat, ash is primarily concentrated in the bran and is an indication of the flour yield that can be expected during milling. In flour, ash content indicates milling performance by indirectly revealing the amount of bran contamination in flour. Ash in flour can impart a darker color to finished products. Products requiring white flour call for low ash content, while whole wheat flour has higher ash content.

1000 Kernel Weight. The weight in grams of one thousand kernels of wheat and may indicate grain size and expected milling yield.

Kernel Size. A measure of the percentage by weight of large, medium and small kernels in a sample. Large kernels or a more uniform kernel size may help improve milling yield.

Single Kernel Characterization System (SKCS). Measures 300 individual kernels from a sample for size (diameter), weight, hardness (based on the force needed to crush) and moisture. Detailed SKCS results (not reported in USW’s Crop Quality Report) include the distribution of these factors, which may be an indicator of the uniformity of the sample and help millers experienced with the system optimize flour milling yields. Kernel characteristics are related to milling properties such as tempering, roll gap settings and flour starch damage content.

Sedimentation Value. A measure of the sediment that results when lactic acid is added to a sifted ground wheat sample and can be used as an indicator of gluten quality and thus the baking quality of wheat flour.

Falling Number. Indirectly indicates alpha-amylase activity, which results from sprout damage. High falling number values indicate low alpha-amylase activity. Sufficient alpha-amylase activity is required in flour for some products such as yeast-raised bread. However, excessive alpha-amylase in wheat cannot be removed and it is difficult to blend to a lower alpha-amylase content. The resulting flour produces a sticky dough that can cause problems during processing and products with poor color and weak texture. Falling number usually correlates closely with amylograph. 

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xtraction. The percentage by weight of flour obtained from a wheat sample. In a commercial flour mill, the extraction rate is critically important to mill profitability. In a laboratory, milling with the Buhler laboratory mill is mainly done to obtain flour for other tests. The Buhler laboratory mill extraction rate is always significantly lower than the rate that can be obtained on a commercial mill, but may be useful for comparison between crop years.

Color. A numerical system to measure a sample’s lightness (L*) on a scale of 0 to 100 for white-black and “chromaticity” or hue on two scales each running from -60 to +60 for green-red (a*) and blue-yellow (b*). High L* values indicate a bright white color, and higher b* values indicate more yellow. Flour color is influenced by the wheat’s endosperm color particle size and the ash content of the flour and often affects the color of the finished product. Durum semolina color is heavily influenced by particle size.

Wet Gluten. A measure of the quantity of gluten in wheat or flour samples as determined using the Glutomatic system. Gluten forms when water is added to the protein in wheat and is responsible for the elasticity and extensibility characteristics of flour dough.

Gluten Index. Also determined by the Glutomatic system and is a measure of gluten strength regardless of the quantity of gluten present. Gluten index is used commercially to select durum samples with strong gluten characteristics. In bread wheat, a variety of factors other than gluten quality can affect the results, though very low gluten index may be an indication of protein damage from insect or disease activity.

Amylograph. Measures flour starch pasting properties that are important to end products such as sheeted Asian noodles. Amylograph also measures enzyme (alpha-amylase) activity which results from sprout damage. Amylograph results usually correlate closely with falling number results.

Starch Damage. The percentage by weight of damaged starch in a flour sample, which is a measure of the physical damage done to starch granules during milling. Bread (hard) wheat flour typically has higher starch damage than soft wheat flour. Highly damaged starch readily absorbs more water, which affects dough mixing and other processing properties. Because starch damage depends on how the sample was milled, starch damage is important for interpreting other results reported.

Specks. Small particles of bran or other material that escaped the wheat cleaning and semolina purifying process and thus depend on the milling process as well as the characteristics of the durum. Specks, which can detract from pasta appearance and desirability, are visually counted in a semolina sample and reported as the number in 10 square centimeters.

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A buyer should be prepared to provide the following information:

• Quantity and loading tolerance

• Quality (be very specific and provide the clients tender specifications)

• Shipment period

• Vessel size and restrictions

• Vessel load and discharge rate guarantees

• Vessel demurrage and dispatch rates

• Loading and discharge capacity

• Number of allowable berths

• Phytosanitary certification requirements

• Mycotoxin requirements

• Proposed method of payment

• Copy of the letter of credit (if this is the proposed method of payment)

• Financial references of your company

• Statement from the buying principal that your firm is the sole and exclusive agent

• Statement from the buying principal that the exporter will not be held liable for brokerages, finders fees, commissions, etc.

• A brief company history, including the names of the officers