ARS develops more precise grain quality test

Correction allows "falling number" test results to be expressed at equivalent lab conditions, such as what exists at sea level.

May 9, 2019

3 Min Read
field of golden wheat field

Scientists and engineers at the U.S. Department of Agriculture's Agricultural Research Service (ARS) developed a more precise method to determine a major factor in grain quality, according to a news release.

Quality testing is dependent on accurate and repeatable tests that assure a fair marketing system. That also means that tests are tweaked and improved to meet the needs of the industry, ARS said. The recent advancement deals with a test known a "falling number" (FN).

FN is a procedure used worldwide to characterize the suitability of wheat for processing into foods such as pan and flat breads, noodles, crackers and cakes.

The procedure relies on heating watery mixtures of starchy materials, like wheat flour, in a boiling water bath. The "falling" number is literally the number of seconds it takes a standardized object to fall through a heated wheat meal/water mixture undergoing starch gelatinization and the enzymatic breakdown of the starch molecule. The longer the object takes to fall — a measure of its viscosity — the better the quality of the sample and the grain lot it represents.

Barometric pressure variation caused by laboratory land elevation and local weather patterns means that the thermal conditions of this test can vary, as can the reported FN. Depending on the land elevation of the laboratory performing the FN test, some lots on the margin may fall above the specification, but when evaluated at a different laboratory — for example, downriver at a sea terminal — the result may fall on the other side. This can lead to uncertainty and inefficiency in the market system.

Commonly, lots with an FN below 300 seconds are discounted by 25 cents/bu. A new mathematical correction addresses this variation problem.

Through experimentation in a low-pressure chamber, ARS agricultural engineer Steve Delwiche and his team at the Food Quality Laboratory in Beltsville, Md., developed the correction so that FN results can be expressed at equivalent laboratory conditions, such as what exists at sea level.

Starting in May 2019, USDA's Federal Grain Inspection Service will implement the correction in a new release of its FN directive. Likewise, the American Association of Cereal Chemists International has amended its "Approved Method" on FN as an optional correction.

Wheat grown in the Pacific Northwest (PNW), which includes Washington, Oregon and Idaho, is a $1.5 billion industry just in terms of the farm-gate price — the price of goods if they were purchased directly from a farm, without markup added by retailers. Most of this wheat crop is exported to customers overseas and is desired for its characteristics in end-product quality, ARS explained.

PNW wheat tends to be grown at higher elevations than other regions in the country. The laboratories that evaluate PNW wheat are at higher elevations too. The high land elevations of grain inspection laboratories in this region result in lower water boiling temperatures and, hence, longer "cook" times during the FN operation.

Implementation of this correction by the grain industry will allow for more accurate management of wheat consignments, which, for lots in the PNW alone that give test results near the 300-second cutoff, may result in savings of $10 million recaptured to the growers in weather-challenged years that foster low-FN wheat.

ARS is U.S. Department of Agriculture's chief scientific in-house research agency. ARS focuses on solutions to agricultural problems affecting America.

Source: Agricultural Research Service, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.

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