Grain Testing
Written by Jeff Hafner, Owner
Harvesting our small grains (wheat, rye, oats) is complete in July, and in August we send our grains in for testing. The United States Department of Agriculture (USDA) has minimum standards for grain that need to to be met for trade and sale. Grain that highly exceeds this standard can be sold or bought for a premium. Non-standard or poorer quality grain can be discounted heavily.
Grain testing includes factors such as test weight, oil content, moldy grain, foreign matter, protein content, and moisture. Some of these standard tests are for food safety like toxin levels (aflatoxin and vomitoxin and other molds). Some are standards for baking quality like ash content, protein, and ‘falling number’. Yet other tests are for organic and/or GMO integrity.
First Tests
The first and probably most common test comes from our own senses (see, feel, smell). Does the grain look good, is there evidence of discoloration or mold, is there a lot of foreign matter (chaff, weed seed, dirt, etc). Does the grain smell good or does it have a musty, moldy, or an off smell. Does the grain feel good or does it feel damp and/or clammy. Grain can be rejected by some of conditions alone.
Foreign matter is the amount of material in the grain that does not belong. Dirt, chaff, rocks, weed seed etc. Grain can be sifted through screens and weighted to get the percent of foreign matter.
Dockage (deduction) for selling is usually on a sliding scale. A sample of approximately 1000 grams is used to determine the percentage of dockage. Wheat dockage is certified to the nearest tenth percent (0.1%, 0.2%, 0.3%, etc.). Dockage usually starts at 4% to 5%.
Test Weight is a measurement of the weight of a volume of grain required to fill level a Winchester bushel measure of 2 150.42 cubic inches (equivalent to 32 quarts) in capacity. Every one talks about bushels per acre (BU/Ac for yield). As described above bushels is a volume measurement. For example, a bushel of cotton balls weighs less than a bushel of sand. There are standards for each grain as far as weight:
56 LBS for corn,
60 LBS for Soybeans,
56 LBS for Rye,
32 LBS for Oats.
If two farmers both had150BU/Ac corn, and one had a test weight of 53 Lbs./BU and the other had a test weight of 57 LBS/ BU. Which one made more money?? The one with a 57 LB test weight. It is possible to be docked for light test weight grain and/or to get a premium for high test weight grain.
Moisture is very important in grain storage, and just as important for selling grain because water has weight. So, 16% moisture grain weighs more than 10% moisture grain. On a similar topic, 10% grain stores better than 16% grain. Our goal is 10% to 12% water weight to mill. Grains need to be dried to below 14% or less to store, and seeds should be dried to below 12%.
Protein Content is mainly evaluated in wheat. Wheat contains the highest amount of protein for grains. Although gluten is the most talked about protein, gluten is not the only protein in wheat and other grains. For example, 16% soft wheat will not make as good of bread as 16% hard wheat because they have different proteins.
Ash content is basically a percentage of what is left when you burn the grain. This is mainly the mineral compounds of phosphorous, potassium, calcium, magnesium, iron, zinc, and copper. This very important in wheat and flour for bakers. Although minerals are throughout the grain, most of the minerals are in the bran (68%) and germ (12%). A high ash content means there are more minerals in the wheat and flour which can affect the baking quality of the flour.
Falling number again is mostly mentioned in wheat testing and quality. It measures the amount of pre-harvest sprouting that occurs in the grain while on the stalk in the field. Low falling numbers lead to poor fermentation and dough quality in baking. Lower than 250 may be rejected by the mill or bakery. Barley being sent to malt houses must have a very high falling number so it will sprout properly during malting.
Another test we watch closely is for aflatoxin and vomitoxin (Deoxynivalenol (DON)), two common toxins that can make the grain unsafe for food or feed in humans or animals. The threshold for vomitoxin is 1 parts per million (ppm) for wheat processed products and 5 ppm for animal feed. Aflatoxin is in a family of toxins produced by certain fungi that are found on agricultural crops such as wheat, maize (corn), peanuts, cottonseed, and tree nuts. For livestock, the aflatoxin standards are 100-300 parts per billion (ppb) depending on species. For humans, 20 ppb or less is the standard.
Each of these tests, from the simple smell of fresh harvested grain to the meticulous lab analysis, are very important to us for human and livestock health as well as maintaining fair and equal trade standards. Regularly committing to these tests also is critical to our mission to providing fresh, healthy food for our community.