How Coffee Is Tested for Mycotoxins (And What Third-Party Testing Really Means)

At a Glance

• Mycotoxins are chemical compounds produced by certain molds during growth and storage.

• Coffee testing measures specific toxins, not “mold” in general.

• Roasting kills mold organisms but does not reliably eliminate mycotoxins.

• Third-party testing varies in frequency, scope, and detection limits.

• Moisture control and storage conditions play a larger role than marketing labels.

Coffee is grown in warm, humid regions where mold can develop during harvesting, drying, and storage. While roasting eliminates living mold organisms, it does not reliably destroy mycotoxins, which are chemically stable compounds produced by certain species of mold under specific conditions.

Because of this, some coffee companies promote “third-party tested” or “mold-free” claims. Understanding what those claims actually mean requires looking at how mycotoxins are tested and what laboratories are measuring.

This article explains how coffee testing works, what labs look for, and how handling practices influence contamination long before beans reach your cup.

What Labs Are Actually Testing For

When coffee is tested, laboratories are not testing for mold in a broad sense. They test for specific chemical compounds.

The mycotoxins most commonly associated with coffee include:

• Ochratoxin A

• Aflatoxins

These compounds form under particular combinations of moisture, heat, and storage stress. Not all mold produces mycotoxins, and not all coffee contains them.

Testing identifies the presence and concentration of these compounds, typically measured in parts per billion.

How Mycotoxins in Coffee Are Tested

Testing generally involves several steps.

1. Sample Collection

Green coffee beans may be sampled:

• At origin

• After drying

• During storage

• Before roasting

• Or after roasting

Where and when testing occurs matters. Contamination can develop during storage even if earlier tests were clear.

2. Laboratory Analysis

Most commercial labs use methods such as:

• ELISA screening tests

• High-performance liquid chromatography

• Mass spectrometry

More advanced methods provide greater sensitivity and accuracy, though they are more costly.

3. Detection Limits

Every laboratory test has a limit of detection. Results may be reported as:

• Non-detectable

• Below regulatory threshold

• Or quantified at a specific concentration

“Non-detectable” does not mean absolute zero. It means the compound is below the test’s measurable range.

What Third-Party Testing Really Means

Third-party testing means an independent laboratory conducted the analysis rather than the company testing its own product.

It does not automatically indicate:

• How often testing occurs

• Whether every batch is tested

• Which toxins were included

• What detection limits were used

• How samples were selected

Two companies can both claim third-party testing while applying very different standards.

Some test every lot. Others test periodically. Some test only green beans. Others test finished roasted product.

Understanding these distinctions is more useful than relying on a label alone.

Roasting and Mycotoxins

Roasting eliminates living mold organisms.

Mycotoxins, however, are chemically stable compounds. Heat may reduce levels slightly depending on roasting conditions, but it does not reliably eliminate them once present.

For that reason, prevention during:

• Harvest

• Drying

• Storage

• Transport

is more impactful than relying on roasting as a corrective step.

The Role of Moisture and Storage

Moisture control is one of the most important variables in mycotoxin development.

After harvest, coffee beans must be dried to precise moisture levels. If moisture remains too high, mold growth can occur during storage.

Important variables include:

• Humidity

• Temperature

• Air circulation

• Storage duration

• Packaging method

Nitrogen flushing and vacuum sealing can reduce oxygen exposure, but they do not replace proper drying at origin.

Prevention earlier in the supply chain tends to have a greater effect than downstream adjustments.

Batch Testing vs Lot Testing

Testing frequency also varies.

Some companies test:

• Random samples at intervals

Others test:

• Each lot upon arrival

A smaller number test:

• Every batch before release

More frequent testing increases the likelihood of identifying variability between shipments, but it also increases operational cost.

Frequency and transparency are often more meaningful than marketing language.

Interpreting Marketing Claims

Terms such as:

• Mold-free

• Toxin-free

• Clean coffee

are not regulated categories.

More informative indicators include:

• Clear explanation of testing methods

• Disclosure of detection limits

• Description of sourcing practices

• Transparency about storage protocols

• Consistent batch monitoring

Companies that explain their process in detail provide more clarity than those relying solely on product claims.

Coffee in the Broader Context of Mold and Food Exposure

Food-based mycotoxin exposure differs from airborne mold exposure in buildings, which we explain in more detail in our overview of mold and mycotoxins.

Food exposure involves ingestion of chemically stable compounds rather than inhalation of spores. The two pathways operate differently and require different strategies for reduction.

Our Coffee Insights page explores how sourcing, storage, and testing practices influence overall coffee quality.

Final Thoughts

Testing for mycotoxins in coffee is about understanding where contamination can occur and how companies monitor it.

The most meaningful control points occur before roasting:

• Proper drying

• Moisture management

• Controlled storage

• Transparent batch testing

Third-party testing can provide useful information, but its value depends on how and when it is applied.

Understanding the process makes it easier to evaluate testing claims and ask informed questions about sourcing and quality control.