Mycotoxin testing for agricultural products is a fundamental food safety control that identifies and quantifies toxic fungal metabolites—such as aflatoxins, deoxynivalenol, zearalenone, fumonisins, and ochratoxin A—in cereals, nuts, fruits, spices, dairy products, and animal feed. Accredited third-party laboratories apply HPLC, LC-MS/MS, and immunoassay techniques in accordance with ISO, EN, and GB standards to verify compliance with statutory maximum limits in domestic and international markets. This guide explains the major mycotoxin classes, relevant sample types, analytical methods, regulatory thresholds, and practical applications across the agri-food supply chain.
Technical Overview
Mycotoxins are low-molecular-weight secondary metabolites produced by filamentous fungi belonging mainly to the genera Aspergillus, Penicillium, Fusarium, Alternaria, and Claviceps. Contamination of agricultural products can occur in the field before harvest, during drying and transport, or during storage, and is promoted by high moisture content, warm temperatures, and physical damage to kernels, seeds, and fruits. Because most mycotoxins are chemically stable and survive typical processing operations such as milling, heating, and extrusion, contamination present in raw commodities frequently carries through into finished foods and feeds.
The toxicological significance of mycotoxins drives strict global regulation. Aflatoxin B1 is a potent liver carcinogen classified as Group 1 by the International Agency for Research on Cancer (IARC), while ochratoxin A and fumonisin B1 are classified as Group 2B possible carcinogens. Deoxynivalenol causes gastrointestinal and immunological effects, zearalenone is estrogenic, T-2 toxin is highly immunotoxic, and patulin is a concern in fruit-based products, particularly infant foods. Regulatory maximum levels in most jurisdictions are set in the microgram-per-kilogram (parts per billion) range, demanding highly sensitive and selective analytical methods.
China regulates mycotoxins under the national food safety standard GB 2761, with corresponding method standards in the GB 5009 series; the European Union enforces maximum levels under Regulation (EU) 2023/915; and internationally harmonized methods are published by ISO and EN. Because mycotoxin contamination is typically distributed heterogeneously in "hot spots" within a bulk lot, representative sampling and rigorous laboratory quality control are as decisive to a valid result as the analytical measurement itself.
Testing Samples
Cereals, Pulses, and Milled Products
Wheat, maize, rice, barley, oats, rye, sorghum, and millet, together with flour, semolina, bran, starch, and breakfast cereals. Key hazards include deoxynivalenol and zearalenone in small grains, fumonisins and aflatoxins in maize, aflatoxin B1 in rice, ochratoxin A in stored cereals, and T-2/HT-2 toxins in oats and other cereals.
Nuts, Oilseeds, and Derived Products
Fresh and Dried Fruits, Juices, and Beverages
Apples, apple juice, and cider are monitored for patulin from Penicillium expansum rot; dried figs, raisins, dates, and apricots are tested for aflatoxins and ochratoxin A; wine and beer are screened for ochratoxin A; and tomato products are increasingly assessed for Alternaria toxins.
Spices, Herbs, and Botanical Ingredients
Chili, paprika, black pepper, turmeric, ginger, nutmeg, and cinnamon show elevated aflatoxin and ochratoxin A prevalence due to open-air drying and tropical storage conditions, and are subject to some of the strictest limits in spices-importing markets.
Coffee, Cocoa, and Tea
Green and roasted coffee, cocoa beans, cocoa powder, and chocolate are tested primarily for ochratoxin A, which is formed by Aspergillus carbonarius and related species during fermentation, drying, and storage.
Dairy Products
Raw milk, milk powder, yogurt, and cheese are tested for aflatoxin M1, the hydroxylated carry-over metabolite of aflatoxin B1 that appears in milk within hours of contaminated feed ingestion by dairy animals.
Animal Feed and Feed Ingredients
Compound feed, maize silage, dried distillers grains with solubles (DDGS), soybean meal, and grain by-products are tested to protect livestock health and to prevent transfer of mycotoxins into meat, milk, and eggs.
Special-Diet and Infant Foods
Cereal-based and fruit-based infant foods are subject to the lowest statutory limits, reflecting the higher vulnerability of infants, and therefore require methods with the lowest achievable quantification limits.
Testing Items
Testing programs for agricultural products typically cover the following regulated mycotoxins and mycotoxin groups:
- Aflatoxins B1, B2, G1, and G2, regulated both individually (B1) and as the sum of the four analogues.
- Aflatoxin M1 in milk and dairy products.
- Deoxynivalenol (DON, vomitoxin), including acetylated derivatives such as 3-Ac-DON and 15-Ac-DON.
- Zearalenone (ZEN/ZEA) and its modified forms, including zearalenone-sulfate and zearalenone-glucoside.
- Fumonisins B1, B2, and B3, regulated individually or as a sum, particularly in maize and maize products.
- Ochratoxin A in cereals, coffee, cocoa, dried fruit, wine, and spices.
- T-2 and HT-2 toxins, regulated individually and as a combined sum in many jurisdictions.
- Patulin in apples, fruit juices, and apple-based products.
- Ergot alkaloids and ergot sclerotia in rye, wheat, and triticale.
- Alternaria toxins, including alternariol, alternariol monomethyl ether, and tenuazonic acid.
- Emerging and masked mycotoxins such as citrinin, sterigmatocystin, and DON-3-glucoside.
Representative maximum levels illustrate the scale of these controls. Under GB 2761 in China, aflatoxin B1 limits range from 5 to 20 micrograms per kilogram depending on the commodity, deoxynivalenol is limited to 1000 micrograms per kilogram in staple cereals, zearalenone to approximately 60 micrograms per kilogram in wheat and maize products, and ochratoxin A to 5 micrograms per kilogram in cereals and legumes. European Union limits for aflatoxin B1 in ready-to-eat cereals and nuts are in the single-digit microgram-per-kilogram range, fumonisin limits in maize extend up to 4000 micrograms per kilogram for raw maize destined for processing, and aflatoxin M1 in milk is controlled between 0.05 and 0.5 micrograms per kilogram depending on the jurisdiction and product category.
Testing Methods
Sampling and Sample Preparation
Because mycotoxins occur unevenly within lots, sampling follows structured protocols such as ISO 24333 for cereals and corresponding national practice under the GB system, involving multiple incremental samples, thorough comminution, and careful sub-sampling to obtain a representative laboratory portion. Extraction is typically performed with aqueous acetonitrile or aqueous methanol, followed by filtration. Cleanup and concentration are achieved using immunoaffinity chromatography (IAC) columns for single-analyte determinations, solid-phase extraction (SPE) cartridges, QuEChERS-type protocols, or dilute-and-shoot workflows for LC-MS/MS. Isotopically labeled internal standards and matrix-matched calibration are used to compensate for matrix effects and ensure quantitative accuracy.
Confirmatory Chromatographic Methods
High-performance liquid chromatography with fluorescence detection (HPLC-FLD), combined with immunoaffinity cleanup and post-column photochemical or electrochemical derivatization, remains a reference technique for aflatoxins, ochratoxin A, and zearalenone. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) has become the preferred platform for confirmatory multi-analyte analysis, enabling simultaneous quantification of dozens of regulated and emerging mycotoxins at sub-microgram-per-kilogram levels, with identification confirmed by retention time and ion-ratio criteria. Method performance is aligned with the GB 5009 series, including GB 5009.22 for aflatoxins B1, B2, G1, and G2, GB 5009.24 for aflatoxin M1, GB 5009.96 for ochratoxin A, GB 5009.111 for deoxynivalenol, GB 5009.235 for zearalenone, and GB 5009.118 for T-2 toxin, as well as with international references such as ISO 16050 for aflatoxins in cereals and pulses, ISO 15141 for ochratoxin A, and EN 14123 for aflatoxins in nuts and derived products.
Immunoassay and Rapid Screening Methods
For high-throughput and on-site screening, enzyme-linked immunosorbent assays (ELISA) offer microgram-per-kilogram-level sensitivity with 96-well throughput, while lateral-flow immunochromatographic strips, optionally read by portable fluorescence or colorimetric readers, deliver qualitative or semi-quantitative results within minutes at grain intake points, silos, and buying stations. Fluorescence polarization immunoassays and biosensor-based platforms provide further rapid options. Positive or over-limit screening results are confirmed using chromatographic reference methods before regulatory or contractual decisions are made.
Method Validation and Quality Assurance
Accredited third-party laboratories operate under ISO/IEC 17025 quality systems and validate methods for linearity, limit of detection, limit of quantification, recovery (typically 70 to 120 percent), repeatability, and measurement uncertainty, ensuring that quantification limits are comfortably below applicable statutory maximum levels. Ongoing quality control relies on certified reference materials, spiked recovery samples, control charts, and regular participation in interlaboratory proficiency testing schemes.
Applications
Mycotoxin testing services for agricultural products support compliance, trade, and safety management throughout the value chain:
- Regulatory compliance testing and market surveillance of domestically produced and imported foods and feeds.
- Grain procurement and intake screening at mills, malting plants, oilseed crushers, and food processing facilities.
- Export certification and import clearance, including certificates of analysis demonstrating conformity with destination-market maximum limits.
- Storage and supply chain monitoring to verify the effectiveness of drying, moisture control, and warehouse management practices.
- Feed safety programs protecting livestock health and preventing carry-over into milk, meat, and eggs.
- Verification of HACCP plans and food safety management systems at critical control points for incoming raw materials.
- Assurance testing for infant foods and other sensitive product categories subject to the strictest limits.
- Applied research, dietary exposure and risk assessment, and investigation of contamination incidents.
By combining statistically sound sampling, validated analytical methods, and interpretation against the applicable regulatory framework, mycotoxin testing enables producers, traders, and processors to segregate or reject non-conforming lots, safeguard consumers, and maintain access to regulated markets.
FAQ
What are mycotoxins, and why are they tested in agricultural products?
Mycotoxins are toxic secondary metabolites produced by molds such as Aspergillus, Fusarium, and Penicillium that grow on crops in the field or during storage. They are tested because many are carcinogenic, immunotoxic, or hormonally active, they persist through processing, and their concentrations in foods and feeds are strictly limited by law.
Which mycotoxins are most frequently regulated?
The core regulated groups are aflatoxins (B1, B2, G1, G2, and M1), deoxynivalenol, zearalenone, fumonisins, ochratoxin A, T-2 and HT-2 toxins, and patulin. Alternaria toxins and ergot alkaloids are increasingly regulated as well.
How do ELISA screening and LC-MS/MS confirmation differ?
ELISA and lateral-flow tests are antibody-based rapid tools suited to screening large numbers of samples cheaply and quickly, but they are semi-quantitative and can be affected by matrix cross-reactivity. LC-MS/MS is a confirmatory technique that separates, identifies, and quantifies multiple mycotoxins simultaneously with high specificity and very low detection limits, and it is the method of choice for regulatory decisions.
Why is sampling so critical in mycotoxin testing?
Mycotoxin contamination is extremely heterogeneous; a single highly contaminated kernel can dominate the result of a poorly sampled lot. Sampling and sample preparation can contribute the largest share of total measurement variability, which is why standardized incremental sampling, thorough grinding, and proper sub-sampling are essential prerequisites for a defensible result.
What detection limits can be achieved?
Confirmatory HPLC-FLD and LC-MS/MS methods routinely achieve limits of quantification at or below 0.1 to 1 microgram per kilogram for aflatoxins and ochratoxin A and in the low microgram-per-kilogram range for deoxynivalenol, zearalenone, and fumonisins, comfortably below statutory limits in all major jurisdictions.
How should samples be shipped and stored before testing?
Laboratory samples should be drawn from a representative aggregate sample, sealed in airtight containers, protected from moisture and heat, and shipped promptly with cooling where appropriate, in order to prevent further mold growth and secondary mycotoxin formation between sampling and analysis.