Posted: Thursday, October 20, 2011 11:00 AM
Matthew Weaver/Capital Press
Wheat consultant Art Bettge checks to see if the falling number machine is hot enough for a demonstration of the process in the Western Wheat Quality Laboratory Oct. 5 in Pullman, Wash.
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'The falling number did not come down from the mountain with Moses'
Capital Press
Several Pacific Northwest grain commissions want to review a test for sprout damage that they say can cost wheat producers money.
The falling number test is used to measure wheat quality, particularly in the event of sprout damage. It involves grinding a small sample of grain and mixing it with water to create a paste, said Craig Morris, director of the USDA Agricultural Research Service Western Wheat Quality Laboratory.
When placed in boiling water, the slurry thickens. If the enzyme alpha amylase, which is associated with sprout damage, is present, it begins to consume the starch, reducing the thickness.
A small, weighted plunger passes through the paste. The test measures the time it takes for the plunger to fall, plus a 60-second initial stirring.
The industry standard for soft white wheat is 300, meaning it takes 300 seconds for the plunger to fall. Numbers below that generally indicate lower quality wheat that could run into processing problems, Morris said. The standard for hard red winter and dark northern spring wheat is 330.
The test is typically conducted by the state and federal grain grading labs managed by the USDA Federal Grain Inspection Service. The grain is delivered to the elevator, then submitted to the lab, said Russ Braun, grain division manager for Primeland Cooperatives in Lewiston, Idaho.
If a farmer's wheat falls below 300 on the test, elevators may discount the price paid. Discounts vary depending on the situation, the falling number and other factors, said Ty Jessup, export industry representative for the Washington Grain Commission.
More growers have complained about receiving a reduced price, said Tom Mick, CEO of the grain commission.
"It's a concern that we have a test out there to determine quality factors that's not repeatable," Mick said.
The Washington commission hopes to assess the test's validity and see if another method could be used, Mick said.
Art Bettge, a retired food technologist at the wheat quality laboratory, recommended farmers get their crop retested, preferably at a different lab.
"The falling number did not come down from the mountain with Moses on the tablets," he said. "There's a chance you might get a higher falling number and there's a chance it might go lower. It might come out worse, but what have you lost?"
Primeland's Braun agrees there is too much variation to the test, but it's the best available. If growers have complaints, he recommends having the sample retested at a different lab.
Blaine Jacobson, executive director of the Idaho Wheat Commission, said asking for a second test to check the falling number has helped alleviate grower complaints.
His commission also put videos on YouTube to inform growers of the issue and their options.
But Jacobson said a better test would benefit the industry.
"If an elevator is tempted to use them as a pricing mechanism, there is the potential for a grower to be unfairly dinged on the price he gets for it," he said.
Bettge also suggested testing whether a falling number actually translates into poor product quality by milling and baking a sample that receives a low number.
Typically, the falling number test is more important for export customers, but Jacobson said domestic users this year are placing more emphasis on it.
Alpha amylase is associated with sprout damage, said Morris, but recently, some wheat varieties have had a genetic defect for late maturity alpha amylase, or LMA.
This year, LMA has been found in varieties never expected to have the genetic disorder. Researchers aren't certain why.
Cool, wet weather conducive to stripe rust, the intensity of stripe rust this year or a fungicide could cause the problem, Morris said.
In a normal year, the test does a good job of checking for preharvest sprouting. But it is susceptible to other influences, Bettge said. It could be a problem with the instrument, a problem with the grain or the actual presence of alpha amylase.
"It's one of those years where wheat does things that we don't understand yet," Bettge said.
Online
Idaho Wheat Commission YouTube videos:
http://www.youtube.com/user/Idahowheat