Mycotoxins in Grains: Identifying and Mitigating Risks in the Milling Process

The significance of mycotoxin testing in maintaining the safety of food and feed grows increasingly evident as the seasons shift and harvest time approaches. Mycotoxins are toxins produced by organisms categorized as fungi, including mushrooms, yeasts, and molds. Fungi of one species or another, or their spores, can be found virtually everywhere. When the growth conditions are right for specific fungi, they will rapidly grow into colonies, and produce toxins specific to that fungus as a by-product. Specific growth conditions, including temperature, humidity, and available organic food sources, can affect whether or not a particular fungus will grow and the characteristics of the mycotoxin it may produce.

Mycotoxins can be produced wherever favorable fungi growth conditions exist, for example, in grains, preharvest in the field, and postharvest in storage. In any case, damage from insects, mishandling, and environmental stress can enable the fungi to invade the grains' seeds. According to the World Health Organization, exposure to mycotoxins can happen either directly by eating infected food or indirectly from animals that are fed contaminated feed, especially from milk.

What are mycotoxins?

Researchers have identified thousands of mycotoxins thus far and continually identify new mycotoxins. Subtypes of numerous mycotoxins have also been identified. Within the identified mycotoxins and their subtypes, a relative few have been determined to pose a significant threat to the health of humans and animals. Those proven to threaten health include aflatoxin, deoxynivalenol (DON or vomitoxin), fumonisin, ochratoxin, T-2/HT-2 toxins, and zearalenone.

Aflatoxin is a toxic and carcinogenic substance produced by certain strains of the molds Aspergillus flavus and A. parasiticus. There are four principal types of aflatoxin: B1, B2, G1, and G2 in grains. Aflatoxin B1 is the most frequently encountered of the group and the most toxic. The commodities most affected by aflatoxin are corn, peanuts, cottonseed, milo, and the majority of tree nuts.

DON is most commonly produced by the pink mold Fusarium graminearum. DON, a member of the trichothecene family, is produced by fungi living on cereal commodities such as wheat, corn, barley, and ensilages. The toxicological effects attributed to DON include nausea (vomiting), feed refusal, gastroenteritis, diarrhea, immunosuppression, and blood disorders.

Discovered in 1989, fumonisins are a family of mycotoxins produced by different species of the mold Fusarium. These molds commonly infect corn (in fact, they are considered ubiquitous in corn) and rice, hence the potential for fumonisins to be found in feed and foodstuffs is high. Fumonisins affect various animals differently and have been linked to esophageal cancer in humans. The Environmental Protection Agency classifies fumonisins as Category II-B carcinogens.

Ochratoxin, commonly produced by the molds Aspergillus ochraceus and Penicillium viridicatum, can be found in corn, barley, green coffee, and various dried fruits. Ochratoxin may be present in conjunction with aflatoxin, one of the most potent naturally occurring carcinogens. In fact, ochratoxin is a suspected carcinogen.

Zearalenone is primarily produced by the mold Fusarium graminearum, which also commonly produces DON. Hence, there is evidence that if zearalenone is detected, there is a high probability that other fusarial mycotoxins may be present. Zearalenone is classified as an estrogenic mycotoxin because it frequently causes estrogenic responses in animals.

T-2/HT-2 toxins are trichothecene mycotoxins produced by several species of Fusarium molds. As T-2 toxin is readily metabolized to HT-2 toxin, and the toxins have been shown to produce numerous adverse effects on many animals, these two mycotoxins are frequently evaluated together.

What are the risks of mycotoxins?

Health Risks to Humans and Animals

• Toxicity: Mycotoxins can cause various health issues in humans, including liver damage, kidney damage, immunosuppression, and even cancer. Animals can suffer from severe liver and kidney damage, gastrointestinal distress, and neurological effects.
• Chronic Exposure: Long-term exposure to low levels of mycotoxins in food can lead to chronic health conditions like liver disease, immune system suppression, and increased risk of cancer in humans. Animals can experience weakened immune systems, reproductive issues, reduced growth, lower milk production, or lower weight gain in livestock.

Economic Risks

• Product Contamination: Mycotoxin contamination can lead to entire batches of grain being deemed unfit for consumption, resulting in significant financial losses.
• Regulatory Compliance: Many countries have strict regulations regarding acceptable levels of mycotoxins in food products. Non-compliance can lead to product recalls, fines, and loss of market access.
• Reduced Yield: Contaminated grains may be rejected or downgraded, reducing their market value, and leading to economic losses for producers and millers.
• Livestock Impact: Mycotoxin contamination may lead to reduced feed intake or poor weight causing decreased productivity, increased veterinary costs to treat mycotoxin-related illnesses, and widespread feed contamination affecting animal products, like milk, eggs, and meat.

Operational Risks

• Processing Challenges: Mycotoxins are resistant to many milling processes, meaning that contaminated grains can carry over into the final product, even after processing.
• Equipment Contamination: Mycotoxins can stick around in milling equipment, leading to cross-contamination of otherwise clean batches of grain.
• Storage Risks: Improper storage of grains can intensify mold growth, leading to increased mycotoxin production. High humidity, poor ventilation, and insect infestations can all contribute to the problem.

Reputational Risks

• Brand Damage: Recalls or reports of contaminated products can damage a company's reputation, leading to loss of consumer trust and a decline in sales.
• Legal Liability: Companies that distribute mycotoxin-contaminated products may face lawsuits from consumers or business partners, leading to legal costs and further damage to reputation.

How can you identify mycotoxins in grains?

Identifying mycotoxins in grain involves a systematic approach that combines visual inspection sampling, rapid testing, and lab analysis. The process typically begins with a visual inspection, where grains are assessed for physical signs of contamination, such as visible mold, discoloration, abnormal odors, or damaged kernels. While these signs alone don't confirm the presence of mycotoxins, they can suggest potential contamination. Dust and debris might also imply poor storage conditions, possibly contributing to fungal growth.

Sampling is a crucial part of determining potential contamination. Grain samples should be collected from various locations within a batch to ensure a thorough analysis, as mycotoxin contamination is often unevenly distributed. Composite sampling, where multiple samples are combined, offers a more accurate assessment of overall mycotoxin levels.

Rapid test kits, such as Lateral Flow Assays and Enzyme-Linked Immunosorbent Assay (ELISA) kits, provide quick and effective on-site testing. Lateral Flow Assays are simple to use and deliver results within minutes, making them ideal for preliminary screening. ELISA kits, while slightly more complex, offer greater sensitivity and are commonly used in laboratory settings for quantitative analysis.

Lab analysis methods like High-Performance Liquid Chromatography (HPLC) are often used as a confirmatory method due to their accuracy and reliability, especially when dealing with complex matrices or multiple toxins.

Sampling is a crucial part of determining potential contamination. Grain samples should be collected from various locations within a batch to ensure a thorough analysis, as mycotoxin contamination is often unevenly distributed. Composite sampling, where multiple samples are combined, offers a more accurate assessment of overall mycotoxin levels.

What are aspects of successful mycotoxin mitigation?

Mitigating the risks of mycotoxins requires a comprehensive approach that includes preventive measures, monitoring, and best practices. Regular testing of incoming grains and final products is essential to detect and monitor mycotoxin levels, ensuring that contaminated batches are identified and removed from the food supply. Good storage practices, such as maintaining optimal temperature and humidity levels, are crucial to preventing mold growth and mycotoxin production. Additionally, regular cleaning and maintenance of milling equipment can help prevent cross-contamination and reduce the buildup of mycotoxins so that products remain safe for consumption.

Addressing these risks requires a combination of preventive measures, regular monitoring, and adherence to strict regulatory standards to ensure the safety and quality of grain-based products. Being proactive with weekly mycotoxin crop reports and staying at the forefront of growing information, trends, and analysis can help producers create early incidence reporting of crop concerns. It can also help with planning tools for mycotoxin risk management and provide tips to assess grain quality quickly. These aspects can help protect both consumers and animals and help protect producers minimize losses.

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