Joshua Liang, Physical Scientist, performs a Falling Number test at GIPSA’s National Grain Center in Kansas City, MO.

ARS Develops Calculation Correction for Grain Quality Test

By Sharon Durham
May 1, 2019

BELTSVILLE, Md., May 1, 2019—Scientists and engineers at the Agricultural Research Service (ARS) developed a more precise method to determine a major factor in grain quality. Quality testing is dependent on accurate and repeatable tests that assure a fair marketing system. That also means tests are always tweaked and improved to meet the needs of the industry. 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 the heating of 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.

Through experimentation in a low-pressure chamber, U.S. Department of Agriculture’s (USDA) ARS agricultural engineer Steve Delwiche and his team at the Food Quality Laboratory in Beltsville, Maryland, developed the correction so that FN results can be expressed at equivalent laboratory conditions, such as what exists at sea level.

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 FN below 300 seconds are discounted by $0.25 per bushel. A new mathematical correction addresses this variation problem.

Starting in May 2019, USDA’s Federal Grain Inspection Service (FGIS) will implement the correction in a new release of their directive on falling number. Likewise, the American Association of Cereal Chemists International (AACCI) has amended their ‘Approved Method’ on FN as an optional correction.

Wheat grown in the Pacific Northwest (PNW—Washington, Oregon, and Idaho) is a $1.5 billion industry just in terms of the farmgate 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 highly prized characteristics in end-product quality.  PNW wheat tends to be grown at higher elevations than other regions in the country. So, too, are the laboratories that evaluate PNW wheat. 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

The Agricultural Research Service is the U.S. Department of Agriculture's chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $20 of economic impact.