Mycotoxins: A Pain in the Ear
Although it’s too early to tell what the 2012 corn crop will look like, mycotoxin-contaminated corn is a recurring issue for ethanol producers.
Mycotoxins are produced by an organism of the fungus kingdom, according to information from the National Corn Growers Association. Fungi spores are found almost everywhere in small quantities, consuming organic matter in conditions where humidity and temperature are sufficient. Mycotoxin development occurs at temperatures from 86 to 110 degrees Fahrenheit, 62 to 99 percent relative humidity and kernel moisture from 13 to 20 percent. Ethanol producers are well aware of what mycotoxins mean for the industry, including the fact that the ethanol production process concentrates the toxins in distillers grains by about three times the levels found in incoming corn.
Recent surveys of mycotoxin levels in corn and distillers grains show overall levels have been low in the 2011 corn crop, although there are some “hot spots.” Two separate surveys of DON (deoxynivalenol, also known as vomitoxin) and ZEA (zearalenone) levels in distillers grains, conducted in late 2011 and early 2012, showed Ohio was an area of concern for mycotoxin contamination in distillers grains. Another mycotoxin study in Iowa is part of a five-year cooperative agreement program through the U.S. Food and Drug Administration. With the help of a $250,000 yearly grant, the Iowa Department of Agriculture and Land Stewardship is recording toxin levels and other information in samples of corn as well as distillers grains and corn gluten, says Travis Knight, laboratory bureau chief for the state’s ag department. The survey, which began in 2010, with the first full year in 2011, is recording the levels of four mycotoxins: aflatoxin, DON, ZEA and fumonisin. Although the projects may differ from state to state, Knight confirms that the FDA awarded grant money to multiple states.
Aflatoxin can be a big problem in the southern states. It does, however, occur in other climates, including Iowa. “It’s usually when there’s some kind of insult to the corn crop, be it a hail storm, or wind damage, or drought stress that can allow some kind of injury that can allow these molds to start to grow,” Knight says. Other mycotoxins, such as ZEA and DON, were a problem in 2009, a wet crop year in many areas. DON and ZEA contaminations start in the field during extended cool, wet and humid conditions in the weeks after corn silk emergence, says Pierce Paul, an Ohio State pathologist. The mycotoxins can also crop up during a wet harvest or in moist storage conditions. “The biggest problems occur when all three of these conditions coincide, wet in field, harvest and storage conditions,” he adds.
So which mycotoxins are of most concern? NCGA points to aflatoxin and fumonisin as the primary toxins affecting corn. As far as the Iowa ag department is concerned, aflatoxin is at the top of the list, partially because it’s the most toxic, points out David McFarland, feed chemist. In fact, before it started on the recent survey of four mycotoxins, Iowa’s ag department had focused solely on aflatoxin. When the five-year project is completed, the state and the FDA should have a better handle on the question of which toxin is of most concern, Knight says. Charles Hurburgh Jr. has an all-encompassing answer for ethanol producers. “All [mycotoxins] are important,” he says, “especially now with the Food Safety Modernization Act.” Hurburgh is an Iowa State University professor in the Agricultural and Biosystems Engineering department and a grain quality expert.
As part of the food and feed supply chain, food and feed safety laws apply to ethanol plants, just as they apply to feed mills or food processing plants. Beginning this year, every ethanol plant must register as a food facility and develop a food safety plan for preventative controls, as well as submit to FDA inspections, Hurburgh says. The law, which the FDA calls “the most sweeping reform of our food safety laws in more than 70 years,” went into effect Jan. 4. “It aims to ensure the U.S. food supply is safe by shifting the focus from responding to contamination to preventing it,” the FDA says on its website.
The results of two mycotoxin surveys were presented March 21 in Des Moines, Iowa, during a half-day meeting sponsored by Nutriquest. Mason City, Iowa-based Nutriquest and David Schmale of Virginia Polytechnic Institute and State University conducted a survey of ZEA and DON levels while Poet LLC did a similar survey on DON levels.
Both surveys pointed to a problem with DON in Ohio, said Ken Purser, general manager of Nutriquest. Looking at the survey results gathered by Nutriquest, Ohio had the highest concentration of DON in DDGS. In fact, there was one sample that contained 16.99 parts per million (ppm.) On average, however, the samples from Ohio contained more than 10 ppm, more than double the FDA advisory level maximum of 5 ppm for swine. “These were samples taken from our customers as well as ethanol plants, so these DDG samples were actually in the feed industry,” Purser said. The Poet survey showed samples taken in Ohio contained, on average, more than 12 ppm DON.
ZEA levels were also higher in Ohio, according to the Nutriquest survey. The samples collected in that state contained an average of more than 0.6 ppm ZEA. Purser recommended that DDGS fed to swine in Ohio be carefully monitored for high DON levels and potential ZEA contamination.
On the other hand, DON and ZEA contamination in DDGS samples in many other states were of less concern. Nutriquest’s survey looked at a total of 141 samples from 83 ethanol plants from 12 states while Poet tested 193 samples of distillers grains from the Western Corn Belt plus Ohio, Indiana, Michigan and Missouri. “The DDGS from other states really appeared to be less affected,” Purser said.
Nutriquest found Indiana, Nebraska, Wisconsin, Iowa, North Dakota, Minnesota, South Dakota, Illinois and Missouri all had DON levels of less than 2 ppm. Likewise, Poet’s testing in the Western Corn Belt found about 1 ppm DON and little to no DON in Missouri. ZEA testing showed slightly less than 0.2 in Michigan and 0.1 or less ZEA in the remaining states on the list.
Why did Nutriquest conduct the survey? Although it’s not something the company does routinely, the company is frequently asked about mycotoxin levels, Purser said, adding that it’s probably the second most common question. The company decided to look at DON levels due to a lot of interest in that mycotoxin, as well as the fact that it was a problem during the 2009 crop year.
Ohio did have a mycotoxin problem last year, Paul confirms, however, it was localized and occurred in fields planted and harvested late under wet conditions. “There is no reason to believe that Ohio is prone to having any greater mycotoxin problems than any other state,” he clarifies. “In any given year, these same set of conditions are equally likely to occur in any other state.”
In Iowa, the mycotoxin survey under way by the state’s ag department showed 2011 probably wasn’t a big year for mycotoxins, Knight says. What they are finding, however, is that it’s fairly common to find detectable levels of all four types of mycotoxins, especially in the ethanol coproduct samples. Part of the reason for that is the fact that the ELISA testing method used is very, very sensitive, he adds. The detection limits for aflatoxin were the most sensitive, at greater than 3 parts per billion (ppb) and the ZEA detection limit was at greater than 20 ppb. On the other end of the scale, DON and fumonisin detection limits were set at greater than 0.2 ppm.
While there weren’t many corn samples that contained detectable limits of aflatoxin and ZEA, the majority of the corn samples contained detectable limits of DON and fumonisin. On the other hand, virtually every sample of both wet and dry distillers grains and corn gluten contained detectable limits of all four. The lowest level of incidence was for the ZEA found in wet distillers grains, which showed up in 17 of the 25 samples. Aflatoxin, DON and fumonisin showed up in every sample of wet gluten. In addition, DON was found in every sample of distillers grains and wet distillers grains. Still, there weren’t very many samples that contained mycotoxin levels that were high enough to cause health problems to animals. “We’re not finding anything that looks very alarming,” Knight said. “In general, there’s not a problem with the amount of mycotoxins.”
For this study, the ag department collected samples on farm, before the corn or coproducts were fed to animals. The goal was to have a more “real world” look at the product animals are actually consuming. “Our numbers might be slightly higher than the numbers you would take if you were to sample [coproducts] directly from an ethanol plant,” he says.
Testing Inbound Corn
Although mycotoxins are a concern, testing all the time, every time at ethanol production facilities just isn’t practical, Hurburgh says. The 10 minutes it takes to complete beta tests and cost of the tests are two reasons for that. Instead, ethanol producers should step up testing as needed. “I have suggested that in every season, the plants keep a running composite for the day and test those for a while in new crop, to see if there is a problem,” he says. “If not, then stop testing.”
Early this year, Charm Sciences Inc. received approval from the USDA’s Grain Inspection, Packers and Stockyards Administration (GIPSA) for a new 5-minute test kit that detects DON in corn and other grains. That’s half the time of previously approved test kits. The enzyme linked immunosorbent assay (ELISA) test utilizes rapid one-step assay (ROSA) technology and requires fewer steps, helping to prevent user errors, says Mark Tess, mycotoxin product manager for Charm Sciences. Unlike other testing methods that require a standard curve be run for each sample to calibrate the system, this test uses a lateral flow methanol that allows for single or batch testing using a calibrated reader. “The ROSA FAST5 DON Quantitative Test has been manufactured to reduce the assay time and meet the new GIPSA specifications required to quantitate DON in the field.” Tess says.
The new tests take advantage of high volume output with batching. In other words, the ROSA incubators can run four test strips at a time and multiple incubators can be used. Another benefit of the test is that it utilizes water for mycotoxin extraction, rather than ethanol or methanol used for extraction by other testing methods.
Testing time is a barrier for farmers, as well, confirmed Charles Ring, a Texas farmer and vice chair of the NCGA Mycotoxin Task Force. The task force met in April in Corpus Christi, Texas, and watched an on-farm demonstration of aflatoxin testing at his farm. “It was interesting to find out what farmers thought after watching a standard test for mycotoxin,” said Ring. “The group expressed their surprise at the amount of time the test requires, about 15 minutes on average. To those outside of farming, this might not sound burdensome, but, during the busy season, it can add a difficult delay into already rushed schedules. While the test is certainly important, it is vital that we continue research on mycotoxin to improve the ways we both manage and test for it.”
NCGA’s Mycotoxin Task Force evaluates the problem, searches for solutions, compares testing procedures and analyzes available research on mycotoxins, Ring says. The group also works with the Aflatoxin Mitigation Center of Excellence, a coalition of southern land grant universities and producer organizations that pool funding sources to study the aflatoxin issue. “We funded six proposals for 2012 with pool money of close to $400,000,” he says. “Unfortunately that was less than half of what was requested. New funding will be one of our goals.”
The task force also follows the labeling of products such as Aflaguard and AF36, a biological control approved by the U.S. EPA for fighting aflatoxin spread in Texas, which it would like to see approved for use elsewhere.
Aflatoxin is a big problem for corn producers. Finding a solution could save millions in crop insurance money that is paid out almost every year in the southern states. “The more northern states have less of a frequency problem, but even then an isolated case could cause alarm with our foreign buyers such as Japan,” Ring says. “Storage problems and long distances will make the problem worse.”
Author: Holly Jessen
Associate Editor, Ethanol Producer Magazine