If you've spent any time in wellness circles, you've probably heard concerns about mycotoxins in coffee, toxic compounds produced by mold that can contaminate food products, including coffee beans. Some brands have built entire marketing campaigns around "mold-free" coffee. So what's the real story?

Here's our take as roasters: mycotoxins are real, the science is nuanced, and the fear is often overblown. Let's walk through what the research actually shows, no panic, no dismissiveness, just the facts you need to make informed choices about your coffee.

What Are Mycotoxins (And How Do They Get Into Coffee)?

Mycotoxins are toxic compounds produced naturally by certain molds. They can grow on various agricultural products, grains, nuts, dried fruits, and yes, coffee beans, particularly in warm, humid conditions.

The two mycotoxins most relevant to coffee are:

Ochratoxin A (OTA): The primary concern in coffee. Produced by Aspergillus and Penicillium mold species, OTA is classified by the International Agency for Research on Cancer as a Group 2B carcinogen, meaning "possibly carcinogenic to humans" based on limited evidence.

Aflatoxins: Less common in coffee but more toxic. Aflatoxin B1 is a Group 1 carcinogen (established evidence of carcinogenicity). It's more of a concern in grains, nuts, and improperly stored foods.

How does contamination happen? Mostly during post-harvest processing:

• During drying: This is the critical window. If coffee cherries aren't dried quickly and properly, mold can develop and produce toxins
• During storage: Warm, humid storage conditions encourage mold growth
• Processing method: Dry-processed (natural) coffees spend more time with the fruit on the bean, creating more opportunity for contamination than wet-processed (washed) coffees

What the Research Actually Says About Health Risks

This is where things get important, and where the nuance lives.

Yes, mycotoxins can cause serious health problems at high exposure levels. Research published in PMC documents that ochratoxin A is nephrotoxic (damages kidneys) and potentially carcinogenic. Aflatoxins are even more concerning, with established links to liver cancer.

But here's the critical context: the levels found in coffee are generally not harmful.

A 2024 worldwide systematic review analyzing over 3,200 coffee samples concluded that "the OTA content of coffee is not toxic to consumers worldwide." The study found that even regular coffee drinkers stay well below the provisional tolerable intake thresholds established by both the WHO/JECFA and EFSA.

To put it in perspective: drinking four cups of coffee daily provides approximately 2% of the ochratoxin A exposure deemed safe by the FAO and WHO. That's a substantial safety margin.

How Roasting Reduces Mycotoxins

Here's some good news if you're concerned about mycotoxins: roasting destroys most of them.

Studies show that the roasting process reduces ochratoxin A levels by 69% to 96%, depending on roasting conditions. By the time green coffee becomes roasted coffee, only about 16% of the original OTA remains.

The mechanisms at work:

1. Thermal degradation: At temperatures above 210°C (410°F), OTA breaks down rapidly, in less than a minute at typical roasting temperatures
2. Physical removal: Some OTA is removed with the chaff (silverskin) that separates during roasting
3. Chemical transformation: OTA undergoes isomerization starting at temperatures as low as 120°C

This is one reason we're fans of proper roasting. Beyond flavor development, thorough roasting serves as a safety mechanism that significantly reduces any mycotoxins present in the green beans.

What About Brewing? Does That Matter Too?

Interestingly, yes. Not all brewing methods extract mycotoxins equally.

Research published in PMC measured how much OTA transfers from roasted coffee into your cup across different brewing methods:

The pattern is clear: more water and longer contact time = more extraction. Quick brewing methods like espresso and ristretto leave more potential contaminants behind in the grounds.

The "Mold-Free Coffee" Marketing Question

Let's address the elephant in the room. Some coffee brands charge premium prices for "mycotoxin-free" or "mold-free" coffee, implying that regular coffee is somehow dangerous.

Here's our honest assessment: most quality coffee tests clean without any special processing.

The regulatory systems in the US and EU already screen for mycotoxin contamination. The European Union has specific limits, 5 μg/kg for roasted coffee, and coffee exceeding these limits can't legally be sold.

Healthline's research review puts it bluntly: paying extra specifically for "mycotoxin-free" marketing is likely unnecessary for most consumers. Quality matters. Processing matters. But the mycotoxin angle is often more marketing than meaningful health protection.

That said, if minimizing any potential exposure gives you peace of mind, there are legitimate factors that can help.

How to Choose Cleaner Coffee (Practical Tips)

While the overall risk is low, here's how to minimize mycotoxin exposure if it's a concern for you:

Choose Quality Coffee

• Arabica over Robusta: Research shows OTA is more commonly detected in Robusta beans (37% of samples) compared to Arabica (26%)
• Wet-processed (washed) coffee: Lower contamination risk than dry-processed. The fermentation step and shorter drying time reduce mold opportunity
• Specialty grade: These beans undergo stricter quality control and are dried to proper moisture levels (10-12%)
• Fresh, small-batch roasted: Better traceability and quality control than mass-produced coffee

Store It Right

• Keep coffee in airtight containers in cool, dark, dry places
• Buy whole beans and grind only what you need (less surface area exposed)
• Don't store coffee for extended periods, freshness matters for flavor and safety
• Empty wet grounds from your filter promptly after brewing

Consider Your Brewing Method

If you want to minimize extraction of any potential contaminants:

• Espresso and ristretto transfer less than drip or French press
• Avoid leaving coffee sitting in contact with grounds (like a French press left to steep too long)

Be Aware of Higher-Risk Products

• Instant coffee tends to have higher mycotoxin levels (EU allows 10 μg/kg vs. 5 μg/kg for roasted)
• Decaf may be slightly higher in mycotoxins because caffeine naturally inhibits mold growth

What This Means for Your Coffee Choices

Let's bring this back to practical reality.

The research is clear: mycotoxins in coffee exist, but at levels that don't pose meaningful health risks for the vast majority of consumers. The roasting process eliminates most contamination, regulatory systems provide oversight, and quality coffee from reputable sources tests clean.

Should you think about it? Sure, it's worth understanding what you're consuming. Should you panic? No. Should you pay a huge premium specifically for "mold-free" marketing? Probably not.

What actually matters for minimizing any potential risk:

1. Buy quality coffee (specialty grade, from transparent sources)
2. Choose wet-processed/washed beans when possible
3. Buy from roasters who care about sourcing (freshness indicates good supply chain practices)
4. Store your coffee properly

At Ember, we source organic, specialty-grade beans and roast in small batches. We do this because it produces better-tasting coffee, but it also happens to address the factors that matter for mycotoxin concerns. Clean sourcing, proper processing, careful roasting.

Frequently Asked Questions

How common are mycotoxins in coffee?

Studies show that 54-58% of coffee samples contain detectable levels of ochratoxin A, with an average concentration of about 3.2 μg/kg globally. However, "detectable" doesn't mean "dangerous", these levels are generally well below regulatory limits and safe intake thresholds.

Does organic coffee have fewer mycotoxins?

Not necessarily. Organic certification addresses pesticide use, not mold contamination. However, organic coffee often comes from smaller, more careful producers with better quality control practices, which can indirectly reduce contamination risk.

Can I taste if my coffee has mycotoxins?

No. Mycotoxins are odorless and tasteless at the levels found in coffee. However, moldy, stale, or poorly processed coffee often tastes bad for other reasons, and those quality issues can correlate with higher contamination risk.

Is decaf coffee higher in mycotoxins?

Potentially slightly higher, because caffeine has natural antifungal properties. But the difference isn't dramatic enough to be a major concern if you prefer decaf for other reasons.

Should I be worried about the mold in my coffee maker?

That's a different issue from mycotoxins in beans. Keeping your coffee maker clean is good hygiene practice, but the mold that might grow in a neglected machine isn't the same as the fungi that produce mycotoxins in coffee during processing.

The Bottom Line

Mycotoxins are worth understanding, but not worth fearing. The science shows that coffee consumption, even multiple cups daily, exposes you to a tiny fraction of what's considered safe. Quality sourcing, proper roasting, and good storage practices address the factors that actually matter.

We believe in transparency about what goes into your cup. That's why we source carefully, roast properly, and ship fresh. Not because we're scared of mold, but because doing things right produces coffee that tastes better and gives you more confidence in what you're drinking.

Shop our air-roasted coffees →