Mycotoxins in cereals are toxins made by moulds in the field or in storage, and they decide whether a lot can be sold as food, as feed or not at all. The EU sets the limits in Commission Regulation (EU) 2023/915 for food and Directive 2002/32/EC for feed, and the sampling rules in Regulation (EU) 2023/2782. Most disputes, however, start with the sample, not the laboratory.
Key takeaways
- Each toxin has a typical crop and weather pattern; test for the ones the season predicts.
- Food limits sit in Regulation (EU) 2023/915, feed limits in Directive 2002/32/EC.
- Regulation (EU) 2023/2782 prescribes the sample, because toxins are unevenly spread.
- Rapid strip tests screen at intake; LC-MS/MS confirms.
- Cleaning lowers some toxins, and bran concentrates them.
The main toxins and where they come from
| Toxin | Main crops | Typical driver | Instrument (food) |
|---|---|---|---|
| Deoxynivalenol (DON) | Wheat, barley, maize, oats | Rain at flowering, Fusarium head blight | Reg. (EU) 2023/915 |
| Zearalenone | Maize, wheat | Wet late season | Reg. (EU) 2023/915 |
| T-2 and HT-2 toxins | Oats, barley | Fusarium in cool, wet conditions | Reg. (EU) 2023/915, as amended by 2024/1038 |
| Fumonisins | Maize | Heat, insect damage | Reg. (EU) 2023/915 |
| Ochratoxin A | All cereals | Poor drying and storage | Reg. (EU) 2023/915 |
| Aflatoxins | Maize | Heat and drought | Reg. (EU) 2023/915 |
| Ergot sclerotia and alkaloids | Rye, wheat, triticale | Cool, wet flowering | Reg. (EU) 2023/915 |
| Tropane alkaloids | Millet, buckwheat, sorghum | Datura weed seeds | Reg. (EU) 2023/915 |
Tropane alkaloids come from weed seeds rather than moulds, but they are controlled in the same instrument and the same intake routine.
Food and feed instruments
Commission Regulation (EU) 2023/915 sets maximum levels for food, with different levels for unprocessed cereals, milled products and foods for infants. The level that applies depends on the stage, so a lot of unprocessed wheat for cleaning and a bag of flour are judged differently. For feed, Directive 2002/32/EC sets maximum contents for aflatoxin B1 and ergot sclerotia, and Commission Recommendation 2006/576/EC gives guidance values for DON, zearalenone, ochratoxin A, T-2 and HT-2 and fumonisins. Guidance values are not legal limits, but buyers write them into contracts. All of these are amended from time to time; reference the consolidated text in force at shipment.
Why the sample decides
Mycotoxins are not spread evenly. A few heavily infected kernels can carry most of the toxin in a lot. A small sample drawn from one spot may miss them or catch them by chance. Regulation (EU) 2023/2782, which replaced Regulation (EC) No 401/2006, therefore prescribes the number of incremental samples, the size of the aggregate sample, how large lots are split into sublots, and how the sample is ground and mixed. It also sets performance criteria for the analytical method and a decision rule that takes measurement uncertainty and recovery into account.
Commercial sampling under GAFTA sampling rules or ISO 24333 serves the contract. It is not the same as official sampling, so the contract should say which applies to mycotoxins. See how grain is sampled for export.
Screening and confirmation
At intake, rapid lateral flow strips and ELISA kits screen trucks in minutes. They are good at sorting clearly low from clearly high. Results near a limit need confirmation by a laboratory using LC-MS/MS, which can measure several toxins in one run. Ask for accreditation to ISO/IEC 17025 for the toxins in scope.
What milling and cleaning change
Cleaning and optical sorting remove broken, shrivelled and discoloured kernels, which often carry more toxin, and they remove ergot sclerotia and weed seeds. Milling then concentrates DON and other surface toxins in the bran, so bran and wholemeal can test higher than white flour from the same wheat. That is why wheat flour, rye flour and bran-rich products need their own results.
Building a seasonal plan
Read the harvest. A wet flowering season in Ukraine raises the DON and ergot risk in wheat, rye and barley; a hot, dry summer raises aflatoxin and fumonisin risk in maize. Increase the testing frequency for the toxins that season predicts, and ask suppliers for their own intake data.
Interpreting a result
A mycotoxin result is an estimate of the lot, not a fact about every kernel. Toxins are unevenly spread, often concentrated in a small share of kernels, so two samples from the same lot can give different results. That is why the official sampling rules set the number and size of incremental samples and why a single result close to the maximum level should trigger a second sample rather than a quick decision.
Read three things on every report: the method and its limit of quantification, the measurement uncertainty, and the sample description. A result reported as below the limit of quantification is not zero; it means the method cannot measure lower. Compare results only when methods and units match.
Responsibilities along the chain
The food or feed business placing a product on the market is responsible for its compliance. In practice, the buyer sets the toxins and the instruments in the contract, the supplier tests at intake and before shipment, and the buyer verifies a share of deliveries. Agreeing the laboratory and the reference method before the season avoids disputes when a result is borderline.
For individual toxins and terms, see ochratoxin A, DON in wheat and oat flakes for the T-2 and HT-2 toxins.
Common mistakes
- Testing a handful of kernels and treating the result as the value for the lot.
- Comparing a rapid strip result with an accredited laboratory result as if they were equivalent.
- Naming a toxin in the contract without the instrument and the version in force.
- Forgetting that cleaning and milling move toxins into by-products such as bran and screenings.
Keep the reports, the sampling records and the contract clauses together for each lot, so a later question from a customer or an authority can be answered from the file.
Checklist
- Toxins in scope chosen by crop and season
- Food or feed instrument named; buyer limits added where stricter
- Sampling basis stated: Regulation (EU) 2023/2782 or contractual rules
- Screening method at intake and confirmatory laboratory named
- Separate results for bran and wholemeal products