Mold In Coffee Beans: How To Save Your Brew!

For many, instant coffee is perfectly fine for their morning brew, but for real coffee lovers, freshly grinding your own beans for each cup is the only way to go.

So what if you open the container you store your beans in, only to find them with a layer of mold? Is the mold dangerous? Why did they get moldy in the first place, and can they be saved?

This article will be answering all of these questions and more, so keep reading!

clean mold on coffee beans

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Why do coffee beans go moldy?

Mold will grow anywhere as long as the circumstances are right, and your coffee beans are unfortunately no exception to this rule.

Mold only needs the following in order to grow and breed:

  • A source of nutrients
  • Humidity levels greater than 55%
  • An ambient temperature between 60 and 80 degrees Fahrenheit
  • A lack of natural sunlight

When we look at how most coffee beans are stored, we can see that these requirements are nearly always met.

In the majority of households, coffee beans will be stored in a cupboard or on the countertop in the kitchen, usually in an air-tight container. Whilst this is usually good practice, should any moisture find its way into the container, you would be giving the mold exactly the moisture that it needs.

Once this container is closed and put back in its place, any mold spores that may have either been in or on the beans already, or any spores that may have landed on them whilst on the countertop can begin feasting on the coffee beans and the nutrients they provide.

The lack of natural sunlight the beans come into contact with as a result of being stored in cupboards or tins protects the mold from the sun’s UV rays. The UV rays would deteriorate the flavor of the beans, so this is an entirely understandable practice, however, the UV would also nearly instantly kill any mold spores.

And finally, the average American thermostat is set to between 68-76 degrees. And although this may be a very comfortable temperature, (as you may notice from above), this also provides the perfect temperature for mold to thrive.

What type of mold grows on coffee beans?

The three most common molds found within the home (and most likely the ones enjoying your coffee beans), are Cladosporium, Penicillium, and Aspergillus.

These strains can be seen in white, green, black, and even blue color variations, and often have a texture that can be described as “fluffy”, but can also be velvety and in some cases, even slimy in appearance.

The strains listed above are just three of the most commonly found molds, but there are literally thousands of others out there, so without testing, it would be very hard to precisely determine the strain you may have in your kitchen.

Is the mold that grows on coffee beans dangerous?

As you will struggle to be able to determine exactly what strain of mold you are dealing with (and going by color alone is not always a good indication), you should always be cautious when attempting to clean or throw away items with mold.

Many strains are entirely harmless, but some have the capacity to create mycotoxins as a defense mechanism whenever they feel threatened. Breathing in any of these toxins from airborne spores can cause breathing difficulties and even attacks in those with allergic asthma.

For others, headaches, nausea, skin irritation, gastrointestinal discomfort, and potential liver damage is documented in cases of prolonged exposure. For these reasons, you should always wear protective equipment if you are planning on coming into direct contact with the mold for cleaning or removal purposes.

How can you tell if your coffee beans have become moldy?

If you open your container of coffee beans and see a white, green, or blue coating on the outer casings of the beans, you can be fairly certain that they have succumbed to mold.

However, this may not always be the case, as mold may be developing deeper down in the container. In this case, rather than sight, you would be more likely to notice mold growing by its scent. The scent of mold is often described as “musty”, and it may remind you of the smell inside a basement or old attic.

And finally, if you couldn’t see it or smell it, the last way you may notice that mold is growing in or around your coffee beans is the taste. If coffee beans have become moldy, they will often have a distinct and unpleasant taste or near complete loss of flavor profiles. So, if you notice a sudden, rapid decline in the quality of your morning coffee, mold may be to blame.

How to clean mold off coffee beans

In most cases, it is advised that upon finding mold in your coffee beans, you should throw the whole batch away to avoid accidentally consuming the mold or its spores, which could lead to the health issues listed above.

If, however, you are truly determined to save your batch, you do have the option to clean the mold off the beans if you are willing to accept the risk involved, and the good news is that the process is fairly simple.

Make a solution of 1 part tap water, to 1 part distilled vinegar and pour the beans into the solution, making sure they are entirely covered. Leave them to soak in this mix for five minutes. After five minutes have passed, you can remove the beans from the solution and wash them thoroughly with tap water.

The vinegar is powerful enough to kill most molds on contact, so it will effectively clean the beans. Ensure that the beans are completely dry before you put them back into their container, or you may find mold growing quickly.

White vinegar isn’t always the easiest thing to get your hands on, so I’ve added a few links to the Amazon store below to make life a little easier. The good news is that vinegar is not only great in sauces and marinades, but it’s also a great mold killer and antibacterial and can be used to clean kitchens and bathrooms too. Clicking on the links below will take you directly to the Amazon store.

Iberia All Natural Distilled White VinegarOpens in a new tab. (US)

Hexeal White VinegarOpens in a new tab. (UK)

Is it dangerous to drink formally moldy beans?

Ok, so you’ve washed your coffee beans, they’ve soaked in the vinegar solution and you’re confident that you’ve killed off all the mold, but could you still get sick from drinking beans that were previously moldy?

The bad news is that, yes, there is a chance that some of the mold on the outside of the beans may have penetrated deeper into the bean itself, so there is a possibility that some small amounts of mold could remain in the middle of the bean.

However, the amounts would be very small and fairly unlikely to cause any real issues unless you were severely allergic to a particular strain.

An important consideration would be that by soaking your coffee beans in a vinegar solution, you may well be removing and killing the majority of the mold that had grown, but you will also be destroying the delicate flavor profiles of the beans you have purchased.

In most cases, if you have found mold growing on your coffee beans, your best bet really is to throw them away and buy a replacement packet. What you are saving in money, you are certainly losing in taste.

How to prevent mold from growing on coffee beans

Prevention is the best cure, so rather than needing to try to rescue moldy coffee beans, you are much better off storing them properly in the first place so they don’t have a chance to become moldy.

In order to keep your coffee beans fresh for as long as possible and with the smallest chance of them growing mold, use the following tips.

  1. Keep your beans as dry as possible (preferably under 55% humidity).
  2. Purchase beans grown at high altitudes, as they have less mold generally.
  3. Store your beans in an airtight container to prevent spore infestation.
  4. Freeze them if you need to, mold will not be able to grow on beans that are frozen.

Are there coffee beans that don’t have mold?

All coffee beans are susceptible to mold, but there are varieties that are grown in higher altitudes that will naturally have a lower amount of mold growing within them to start with.

Arabica beans are grown at a height between 1,800 – 6,300ft, making them one of the varieties that tend to have a slightly naturally lower level of mold growth. Despite this, if you do not store your beans correctly, and ensure you have taken the steps listed above, your coffee beans will still become moldy.

Keeping your beans stored in as dry a location as possible, whilst in an air-tight container and periodically checking on them is your best bet against moldy coffee beans.


Moldy coffee beans can be saved for later use as long as you get to the mold and remove it quickly. If it has been growing for a considerable amount of time, it may have penetrated deep into the center of the beans, making them unfit for consumption. Using the method above may affect the taste of your brew slightly, but it will at least allow them to be used.

Chris Walker

Chris Walker has struggled for several years with mold after buying his own property. After finding the solutions to several issues around his home, he decided to create this site in order to answer as many questions about mold and mildew as possible to help others dealing with the same problems.

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