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Just the facts

AMMO workshop serves as a one-stop-learning shop for falling number issue

March 2017
By Trista Crossley


Harvest may be long over, but discussions about quality issues that plagued the 2016 crop haven’t fallen silent.

The Agricultural Marketing and Management Organization (AMMO) tackled falling numbers—causes, testing and impacts on flour quality and marketing—in its first workshop of 2017 last month. Using experts from several different fields, the session served as a one-stop shop for all things falling numbers (FN).

Causes of low FN
Camille Steber, a molecular geneticist with the U.S. Department of Agriculture’s (USDA) Agricultural Research Service (ARS), reviewed the genetic causes of low FN:

• Preharvest sprout, which is germination of the mature grain induced by cool, rainy conditions occurring before harvest; and

• Late maturity alpha-amylase (LMA), which is induced by sudden temperature swings within 25 to 35 days after pollen shedding.

At the root of both causes is an enzyme, alpha-amylase, that is normally activated during germination to help grain sprout. The enzyme works by cleaving starch chains to provide fuel for the sprouting seed, but in the process, degrades the starch and causes quality problems in baked goods.

Low FN due to preharvest sprouting has long been a problem, and one of Steber’s research goals is to find the balance between dormancy, which offers resistance to preharvest sprout, and emergence, which calls for activating the alpha-amylase so the grain can begin sprouting.

“Dormancy and emergence are two sides of the same coin,” she explained. “If we select for higher dormancy so that we don’t get preharvest sprouting, you get poor emergence or uneven emergence of the seedlings. When we select for good yield, often we are selecting against seed dormancy and preharvest sprouting tolerance.”

In the 2016 harvest, growers experienced both causes of low FN, sometimes in the same field. Steber said from a genetic standpoint, comparing these two causes is like comparing apples and oranges because the two traits are disconnected and need to be independently selected for during breeding.

Steber listed other factors that might affect FN:

• Starch properties. Waxy wheat tends to be more susceptible to low FN.

• Protein. Higher protein tends to produce higher FN.

• Fungicides. Initial research indicates that in disease-resistant varieties, fungicides seem to have no significant effect on FN.

• Storage. Some literature suggests that storing moderately low FN wheat at higher temperatures can increase FN, but Steber cautioned growers against unrealistic expectations. In two studies that she used as examples, one study stored grain for three months at 100 degrees F or 60 degrees F. The grain stored at 100 degrees showed a 50 second increase in the FN score, but no increase in the grain stored at 60 degrees. In another study, grain stored for five months showed an increase of 25 seconds at 73 degrees and a 35 second increase at 95 degrees.

“The message is, once it gets cold outside, home storage may not help you. Most of the increase you are going to see is going to be while the temperatures are higher,” she said. “The other thing you need to know is that storage doesn’t seem to help once falling numbers get very low, either because there is already damage to the starch or because there is so much alpha-amylase that you can’t wait it out.”

Impact on flour quality
Another USDA-ARS employee, Craig Morris, a supervisory research chemist who directs the Western Wheat Quality Lab on the Washington State University (WSU) campus, tackled the effects low FN has on flour quality.

While some alpha-amylase is desirable in bread (it converts starch to sugars to feed the yeast), the same can’t be said for cakes and cookies. Morris used slides showing samples of sponge cakes to illustrate how flours with different FN performed. The cakes made with low FN flours were reduced in volume and the tops of the cakes had caved in.

“Alpha-amylase and sprout harm different products to a different degree, but unlike bread, it’s never good. It may have a small effect or a large effect, but it’s always a bad thing,” he explained.

It only takes a few sprouted kernels to make an impact. Morris talked about a study done at the University of Idaho where researchers took one sprouted kernel and mixed it with 2,600 sound kernels. That one sprouted kernel was enough to make the resulting flour’s FN score drop by 100 points. And unlike protein, it is very difficult to blend low FN wheat with high FN wheat to make it work better. And it’s not just baking quality that is affected by low FN wheat. The amount of flour that can be produced is also reduced, typically by 3 to 5 percent, which could cost millers thousands of dollars a day.

“You have to use more wheat to get the same amount of flour out of your mill,” Morris said. “Not only are you producing flour that may not make your customers happy, but your actual milling operation is really suffering.”

Morris also talked about some of the studies the wheat quality lab undertook during harvest last year when reports of low FN started to surface. He and a group of colleagues used samples from the Federal Grain Inspection Service and from WSU’s variety testing program. The experiments included:

• Does removal of the bran affect the amount of alpha-amylase in the flour? They found that the resulting flour had less of the enzyme but it was still present. “You can’t mill away alpha-amylase once it is in the grain,” Morris said.

• Is the stirring number test better than the falling number test currently used to measure FN? The stirring number test was developed in Australia specifically to measure sprout damage at the first point of grain receival, such as an elevator. Morris’s tests showed that there was very little one-to-one correspondence between the results of the stirring number test vs. the Hagberg-Perten test, and the stirring number test may be better used simply as a segregation tool. “I can’t judge which one is better, but they don’t agree with each other,” he explained.

• How does low FN flour affect different baked goods? The tests showed that low moisture/high sugar/high fat products, such as cookies, showed only a small effect. They also baked sponge cakes, but had some surprising results. In short, they didn’t see as much of the classic structural problems they were expecting. “Our operating hypothesis is that a lot of 2016’s low FN was the result of LMA, and I don’t know that we have the historical knowledge base on LMA to really know what it is doing to our product quality like we have with preharvest sprout,” Morris explained, adding that some of the differences between the sponge cake tests could be due to genetics, not to mention that there might be different groups of enzymes or proteins in play with LMA and preharvest sprout. “I think what we are seeing is probably an overlay of genetics, environment, LMA and sprout.”

Testing for alpha-amylase
Much of the FN discussion has centered on the test that is used to measure low falling numbers, with some growers questioning its precision and reliability. Don Potts, the Eastern Washington regional manager of the Washington State Department of Agriculture’s (WSDA) grain inspection program, and Austin Danielson, a WSDA grain inspector, brought one of their Hagberg-Perten test machines to demonstrate how the test is run and explain the testing protocols they adhere to. Despite a few initial hiccups, Danielson was able to run the test smoothly, while Potts answered growers’ questions.

In a normal harvest, Potts said the Eastern Washington offices (Spokane, Colfax and Pasco) would run about 8,500 FN tests; since the 2016 harvest began, they have run approximately 22,000 samples through the test.

“Our first indication that it (the 2016 harvest) wasn’t going to be normal, was in the Walla Walla area where we got a hard red winter sample around 220, and there was no rain,” Potts said. “To us, that was impossible. We didn’t know about LMA, we just knew about sprout. No areas got rained on. The wheat itself was gorgeous…to see a falling number like that, you can usually tell coming in the door what the falling number (is going to be).”

Potts said for each batch of kernels they receive, they run two tests and average the two scores. If the two scores are more than five percentage points apart, the tests are rerun. They’ve taken out as much human variability as they can by carefully detailing every step, weighing amounts at every step and automating every step they can. They’ve even gone so far as to detail how the slurry should be scraped from the sides of the test tubes.

“For us, it is the only test that is available, and we take it very seriously,” he said.

Variety selection and low FN
Ryan Higginbotham, a WSU Extension specialist who runs the cereal variety testing program, addressed ways farmers can manage risk by picking wheat varieties that might be less prone to low FN.

“Can you plant something that’s less prone to low falling numbers? Everybody knows environment plays a role. You are less likely to have low falling numbers if you don’t have rain or you don’t have these temperature swings. It is the environment, yes, but there’s genetics that are interacting in that environment. So it takes a combination of both,” he explained.

Some of the ways Higginbotham said farmers can manage risk through planting selections include:

• Don’t plant your whole farm to one variety;

• Plant varieties of different maturity;

• Plant varieties that seem to be less prone to low FN.

To look for varieties that show some resistance to low FN, Higginbotham took results from Steber’s website (steberlab.org) where she has four years of falling number information from his own variety trials. By averaging plots that clocked in with FN scores below 300, he came up with a percentage ranking for each variety. Higginbotham warned the group that this was his unscientific assessment of a variety’s risk for low FN and that farmers should look at the data and make their own conclusions.

“It just depends on how much risk you are willing to take,” he said, adding that there was no statistical analysis involved in his summaries. He also suggested that there are other variety selection criteria to look at.

“There might be varieties that are very high risk but are also very high reward, or they might be low risk but are not a good fit for your area. There might be a variety that has never had a falling number below 300 but it’s not going to yield worth a darn in the Palouse. So there are other things to consider besides just falling numbers. You have to factor in other issues.”

Higginbotham hasn’t made his tables available online, but farmers interested in looking at them can email him at rhigginbotham@wsu.edu.

Low FN from a marketer’s point of view
Carolyn Hotchkiss, a grain merchant from United Grain Corporation (UGC) in Vancouver, Wash., said that since July of 2016, 18 percent of the soft white wheat (SWW) barges UGC has unloaded have had falling numbers below 300 with the lowest being 255. Thirty-two percent have been between 300 and 320 (also known as scratch 300), while 50 percent have been above 330.

“FN issues are difficult for exporters to work through,” she said. “We are susceptible to the same tests everybody else is. Those 32 percent of the barges I unloaded that were scratch 300, we all know that when it retests, it can test at under 300 the second time around. This creates a need for supplemental, higher falling number wheats laying around in case I get into trouble on loading vessels.”

Hotchkiss explained that reinspected barges that get a second, higher FN score still get binned with their original grade—especially important for those that graded below 300 because “…if it graded it once, it can grade it again, and we can’t take the risk when loading boats of having a grade below what we expect in-house.”

Hotchkiss said UGC has some procedures in place to help mitigate low FN wheat with knowing ahead of time what’s coming down from the elevators being the most important. When they have a shipment of low FN wheat, they have to plan to:

• Have a supplement supply of better quality wheat available;

• Have a vessel that can accommodate the shipment; and

• Have the time and space to babysit the lot.

Closing remarks
Alex McGregor, president of The McGregor Company, closed out the workshop, lauding efforts by the Pacific Northwest wheat industry to address the FN issue, through meetings with state and federal agencies, increased research funding and a search for better testing methods.

“All of us who raise wheat, whether impacted by the luck of the draw, need a better measuring system for the future,” he said. “My personal goal ever since we met here back in early September with Rep. Cathy McMorris Rodgers, Farm Service Agency leader Judy Olsen, WSDA Director Derek Sandison, State Rep. Mary Dye, association and commission leaders, grain inspection professionals and university researchers has been to encourage all of us to get something done and to make sure the issue doesn’t fade from attention as we move onto a new year’s crop.”

McGregor called out the partnership between the Washington Grain Commission and the Washington State Department of Agriculture that is seeking an increase in research funding from the Agricultural Research Service and working with the Grain Inspection, Packers and Stockyards Administration to improve existing protocols.

He also touched on the issue of the Risk Management Agency (RMA) implementing quality discounts that can impact a producer’s actual production history even if no claim is filed. The Washington Association of Wheat Growers is working with other states to change the way RMA applies quality discounts.

McGregor ended his comments by talking about the importance of pulling together to win the battle against low FN. He asked attendees to be ready, when the call comes, to mount a grassroots effort towards a new and improved system of testing for FN.

“We’ve got a record of pulling together and getting things done. It’s a proven, time-honored record of WSU, agencies, associations, growers and local agricultural businesses working together. It dates back to 100 years ago when wheat growers went to the Pullman campus and urged professors to get some time out of the classroom and help us bring science down out of the skies and hitch it to our plows. Today, our plows may be in fencerows, but our tradition of pulling together to get results is stronger than ever,” he concluded.