Ask the Expert: Mycotoxins & Grain Grading
With over two decades in the grain inspection industry, Cheryl Muse, Rail Manager at Eurofins Grain Inspection, has developed a sharp eye for detail and a deep understanding of the complexities behind grain and rail inspections. Her experience spans thousands of samples, countless harvests, and a wide range of commodities, making her a trusted voice in the field.
Cheryl’s expertise ensures that clients receive fast, accurate results, even when unexpected challenges arise. In this blog, she shares firsthand observations, practical tips, and the subtle signs inspectors look for when evaluating grain quality and potential mycotoxin risks.
Let’s dive into the nuances of grain grading and explore how Eurofins Grain Inspection tackles the tough questions with precision and care.
Can there be a correlation between commodity grade and mycotoxin prevalence?
While certain grading factors like mold and cob rot can suggest the presence of mycotoxins, the relationship isn’t always direct. Mold may be present without measurable mycotoxin levels, and conversely, mycotoxins can exist even when visual indicators are absent.
At Eurofins, with nearly 50 years of grain inspection experience, we’ve seen cases where visual cues during grading, such as kernel discoloration or surface texture, prompted us to recommend further testing, even when environmental conditions didn’t suggest elevated risk. Grain grading is both science and art, and trained inspectors often spot subtle signs that warrant a second look.
Which commodities are most affected and why?
Corn and wheat are the most susceptible to mycotoxins due to their vulnerability to specific fungi:
- Aflatoxin in corn
Caused by Aspergillus ear rot, which appears as olive-green mold, often at the ear tip. It thrives in hot, dry conditions and affects stressed plants which are those impacted by drought, nutrient deficiencies, or insect damage. - DON/Zearalenone in corn
Linked to Gibberella ear rot, which produces pinkish mold. It’s more common in cool, wet weather during early silking and worsens with delayed harvests. - DON/Zearalenone/Fumonisin
Associated with Fusarium ear rot and head blight. These molds appear as scattered or patchy damage and are triggered by warm, wet conditions and physical damage to ears.
Understanding the environmental triggers and visual markers of these molds is key to anticipating mycotoxin risk.
What grading factors are most relevant to mycotoxin risk?
- Type and extent of damage
Mold-related damage is a strong indicator. Many fungi responsible for ear rots also produce mycotoxins. - Broken Corn and Foreign Material (BCFM)
While BCFM can suggest increased risk, since broken kernels are more vulnerable to mold, it’s not always a direct correlation. BCFM levels can rise due to harvesting practices or drying methods, not necessarily fungal contamination. - Odor Mycotoxins themselves are odorless. However, molds that produce them may emit musty or earthy smells. Still, not all musty odors indicate mycotoxins, and not all mycotoxin-producing molds smell.
Are specific mycotoxins linked to certain grading observations?
Yes, and this is where expert eyes matter most.
- Pink Mold vs. Pigmentation
Some corn varieties naturally have pink pigmentation. Trained inspectors know how to distinguish this from Gibberella mold, which can signal DON or Zearalenone contamination. - Dirt vs. Damage
Dirt is common and not inherently harmful. However, it can be mistaken for mold. Proper inspection techniques help differentiate between harmless debris and actual fungal damage. - BGYF (Bright Greenish Yellow Fluorescence)
This black light test is a quick field method to screen for potential aflatoxin contamination. While useful, it’s not definitive, mold may be present without producing toxins, and vice versa. - Foreign Material vs. Damage
Not all discoloration or irregular shapes are damage. Damaged kernels have a clear definition. Just because it is misshapen, elongated, discolored, or “ugly” does not. make it damaged. Trained inspectors rely on visual references and experience to make accurate calls.
When should mycotoxin testing be recommended?
Grain inspectors consider several factors before suggesting mycotoxin testing:
- Growing Conditions
Hot, dry seasons raise aflatoxin risk; cool, wet conditions during silking increase DON and Zearalenone potential. - Visual Indicators
Presence of olive-green (Aspergillus), pinkish (Gibberella), or cottony white to salmon-pink (Fusarium) mold during grading can trigger testing recommendations. - Sampling Accuracy
Mycotoxin levels can vary dramatically from kernel to kernel. A representative sample is essential—poor sampling can lead to underestimating contamination.
Did you know? Mycotoxins can develop in the field, during harvest, or in storage. Temperature, humidity, and rainfall all play a role in their formation.
Final Thoughts
Grain grading is more than checking boxes. It is about interpreting subtle signs, understanding environmental context, and knowing when to dig deeper. Mycotoxins are invisible, odorless, and dangerous. That’s why experience, training, and a sharp eye are essential in protecting the integrity of the food and feed supply.
Partner with our experts to maintain the highest standards of grain safety and quality from field to storage.
