Coffee enthusiasts everywhere can attest to the fact that they love walking into a coffee shop or kitchen and finding the delicious aroma of coffee. It’s a warm and relaxing smell to wake you up in the morning or get you through a midday slump. Coffee not only tastes delicious and provides you a boost; it’s an entire experience. If that aroma isn’t right, it can really throw things off.
The fishy smell of coffee beans is due to the chemical reactions that take place during the roasting process. Dark roast coffee is more susceptible because it has a longer roasting process and more exposure to heat.
Some people love a coffee shop for studying or getting their work done. It creates a very diverse and welcoming environment. Now imagine expecting your usual pleasant, peaceful aroma while opening up your bag to start your coffee or walk into a coffee shop and immediately being assaulted with a smell that is rank and fishy. Surprisingly, it does happen. Whether at home or at a café, that characteristic coffee smell is an important part of it all. So, if a fishy aroma has ruined your scene, maybe we can help put your mind at ease.
Why Do Your Coffee Beans Smell Fishy?
Nothing’s worse than expecting the usual pleasant aroma of coffee and instead, being assaulted with a smell that is rank and fishy. Surprisingly, it does happen. And it’s nothing to worry about! The smell is due to the chemical reactions that take place during the roasting process. Dark Roast coffee is more susceptible because it has a longer roasting process and more exposure to heat.
Again, back to the culprit – chemical reaction. In the process of drying and roasting coffee, chemical reactions occur. When the outcome of the process is a fishy aroma, there are three common contributing factors. It could be:
- The result of immature green beans used in the roast
- Oxidation during storage
- The hygroscopic nature of coffee beans
- Improper storage
- Unclean equipment
No matter which one has led to you experiencing the unpleasant smell of fishy coffee beans, there is no cause for alarm. The smell happens and is nothing that should concern you. If the smell doesn’t bother you, then the beans are fine to use. However, if you find any mold or rancid beans, be sure to get rid of those.
Let’s take a closer look at some reasons behind that shady smell.
Immature Coffee Beans
The flavor of your cup of joe can be greatly affected if beans aren’t properly matured. Immature beans can result from 4 things:
- Harvesting underripe fruit
- Growing in an unsuitable environment
- Lack of fertilizer
- Drought or rust disease affects the coffee tree
To give you an idea of the difference between a mature and immature bean, consult a chart like this one. The problem is after the coffee’s been roasted and takes on the characteristic brown hues, you won’t be able to tell if the bean was immature. Not until you taste the coffee brewed from it, that is!
Oxidation During Storage
Heat and moisture exposure can cause oxidation to occur. This results in stale coffee. It can affect taste and smell. To avoid this, once you bring the coffee home, practice good storage habits. Unfortunately, if the roaster didn’t store the coffee appropriately between roasting and bagging, you may still end up with some oxidation and fishy coffee.
We’ll talk a little more about this later when we discuss the right way to store your beans.
The Hygroscopic Nature of Coffee Beans
Coffee beans are sundried, which significantly reduces their moisture content, and then they are further dehydrated throughout the roasting process. The water extraction quickly leads to what is termed the ‘first crack’ in the wall of the bean, and a ‘second crack’ can later occur in the process. This leaves the coffee beans wanting to reabsorb moisture.
Hygroscopic means that they absorb moisture from the air and aromas from their surrounding environments. Coffee beans are hygroscopic, and ground coffee beans are extremely hygroscopic. If you left your beans exposed to unsavory flavors, well – that could end up in your morning coffee.
On the flip side: This hygroscopic ability may be why coffee beans are often recommended as natural air fresheners and deodorizers. Just throw some coffee beans in your fridge if you need to deodorize.
Improper Coffee Storage
Storing your coffee is very important to keep it fresh and flavorful. You should use an airtight container. Vacuum sealed is even better. Since coffee is so hygroscopic, proper storage is imperative for the integrity of your beans. Do not keep coffee in the refrigerator – ever. They will take on the odor and flavor of what’s around them: onions, fish, tuna salad – you get the idea.
Also, keeping smaller batches on hand is essential in maintaining fresh coffee. Try to use your coffee within a week of breaking the airtight seal. And keep them tightly sealed in the meantime.
Your Coffee Equipment Needs Cleaning
Over time, if you don’t clean your coffee equipment, those coffee oils build up and hang around. No matter how fresh your beans, if they encounter stale coffee oils during the brew, your flavor is going to be off.
One way to keep the taste and aroma of your coffee at their best is to make sure you clean and maintain your brewing and grinding equipment regularly.
Cleaning Your Coffee Maker
Begin by taking off the removable parts and wash them using soap and water. Depending on your manufacturer and their care instructions, you may be able to run these pieces through your dishwasher. The dishwasher is my preferred method. Unplug your machine before wiping down the outside.
To further clean and descale your coffee maker run equal parts of water and white vinegar through the machine. After this has gone through your coffee maker, run the next cycle with just water to clean all the water and vinegar solution out. Then you are good to go. Ideally, you should aim to do this monthly.
Cleaning a Single-Use Coffee Pod Brewer
| Daily | Rinse your pot after each use. Don’t let coffee grounds sit for hours. A quick rinse of the water reservoir, coffee carafe, and reusable filter every time you use it will go along way toward fighting stale coffee oil build-up. |
| Weekly | If you use a single-use brewer, such as a Keurig, the weekly cleaning schedule should include washing all of the removable parts such as: - The water reservoir and lid - Mug tray - Coffee pod holder - Don’t forget to unplug your machine and wipe down the sides. |
| Monthly | Replace the water filter |
| Every 3 or 4 months | Descale your machine using a cup of white vinegar or descaling solution through your device. Do this two times. Follow this by running a cup of water through the machine. Then you are done. |
Don’t Forget the Coffee Grinder!
If you prefer buying coffee beans or you roast your beans, then you probably use a grinder. To clean the grinder, you need to run ¼ cup of dry, uncooked rice through the machine. Then unplug and wipe it clean with a damp cloth.
The Basics of Coffee Roasting
Since we mentioned how the darker the roast, the higher the possibility for a fishy smell, let’s just cover a very high-level overview of the coffee roasting process.
Coffee is made by first removing the outer skin, pulp, and inner parchment skin. After that, the remaining part is the inner seed, otherwise known as the dried coffee bean. During roasting, moisture moves out of the bean. There are natural sugars converted to CO2 gas and other sugars caramelize to create unique, complex flavors. That green bean from the beginning transforms into a brown bean. These are those chemical reactions we talked about.
Some coffee lovers, in their search for the perfect flavor, decide to take matters into their own hands. Home roasting can be done in small batches right in your kitchen – and it doesn’t have to require expensive, specialized equipment.
How You Can Roast Your Coffee Beans at Home
If you want to try to roast coffee beans yourself because you just love coffee or want to find the perfect flavor profile, here’s how to get started.
- Begin by purchasing green coffee beans.
- Next, pick your roaster: sauté pan, stovetop popcorn maker, or cookie sheet/oven.
- The roasting temperature is between 370℉ to 540℉, and the beans must be continually moving to avoid burning them. So, a spatula and oven mitt are essential!
- This process must take place in a very well-vented area.
The beans are going to go through numerous stages: yellowing, first crack, first roasting stage, caramelization, the second crack, and the darkening roast. Many light roasts stop at the caramelization phase. The darkest roasts go all the way through.
You can experiment to see where you prefer to stop roasting and, through the process, control your beans flavor profile. Learning to roast may take a little trial and error. If you want to avoid fishiness, stay away from the very darkest roasts.
This is one way to get fresh, flavorful coffee. There are plenty of coffee aficionados who have tried this out on and shared the results on YouTube. Check out videos like this one to get an idea of whether this idea is right for you! The National Coffee Association also has a lot of great information about roasting.
Expert tip: To avoid getting a fishy aroma in your DIY beans, consult a chart to ensure you are using mature beans and store your coffee properly to keep it smelling fresh.
No Need to Worry About Fishy Smelling Beans
The smell is a normal occurrence, and it doesn’t even bother many people. It happens naturally during the roasting process. Look for brands and roasts that you love. If you are sensitive to the fishy smell, opt for a lighter roast, since they are less likely to be affected.
If the smell is due to stale beans or gunked-up coffee equipment, do a thorough cleaning, purchase fresh beans, and try again. You’re bound to be happier with the results.
If you feel so inclined, try roasting your own. One way or another, you’re sure to find something that suits your taste buds and makes every cup taste and smell great!