Coffee addicts around the world are turning to brew their coffees at home. You might have picked up your favorite batch of beans from your local roaster, only to bring them home and notice they are oily. Is there something wrong with your coffee beans, and should coffee beans be oily?
Coffee beans should be oily if they are dark roast beans. The oil comes from the beans themselves. It is either released during the roasting process or from extended storage, and dark roast beans will have released oils during roasting. However, medium and light roasts should be dry.
Learn what the oil on coffee beans is, why it’s there, and where it comes from in this article. You’ll also learn what a normal amount of oil is for specific coffee beans and when it could be damaging to your coffee machine.
Why Are Coffee Beans Oily?
The oil on your coffee beans comes from the beans themselves. The oil is not an additive to preserve the beans or alter their flavor. Oil is released from the coffee beans naturally during extended periods of roasting and storing.
Beans roasted for a long time will release more oil during the process, therefore making the finished product oily. Beans that are only roasted lightly will not have time to release many oils, and the finished product will be dry. Over time, if the beans are stored for a long period, they will slowly release and become oily.
What Is the Oil on Coffee Beans?
As mentioned, the beans themselves release the oil that you see on their surface. This oil is a natural product and comprises lipids, the molecular component found in many fats and oils. As the coffee beans are heated, the lipids are forced outward, but only if they are roasted for a particularly long time.
Where Does the Oil on Coffee Beans Come From?
When coffee beans are first put in the roaster, they have a light, off-white color. As the steam increases the coffee beans’ pressure, the sugars and amino acids react to the pressure, and the beans turn light brown. The structure of the bean begins to break under pressure, and the beans eventually crack. This moment is known as the “first crack,” and light roasts are pulled soon after this moment.
Medium roasts stay under pressure and continue to deepen in color. The darker brown beans can be pulled whenever the roaster desires to create their signature flavor. If the beans are destined to become a dark or french roast, they will stay under pressure until the infamous “second crack,” releasing many of the lipids stored inside. This second crack is why dark roasts are oily as soon as they are finished roasting.
Are Oily Beans Good or Bad?
There is no blanket answer to whether oily beans are good or bad. The oil on certain beans is perfectly normal, but it can signify an old bean on others. Coffee beans should be ground and brewed as close to their roasting date as possible; this ensures freshness and flavor.
As roasted coffee beans age, they release more oil, and their flavor changes, becoming increasingly acidic and stale. Therefore, oily beans can signify old beans that have been sitting around for too long. Some beans are oily as soon as they are roasted, though, and even fresh beans will be oily.
Light Roast Beans vs. Dark Roast Beans
To put it simply, if your dark roast or French roast beans are oily as soon as you buy them, then that is perfectly normal. They could be old beans, but it’s more likely that they are fresh. If the beans seem excessively oily, then you might want to be a little warier when you take the first sip of coffee; the beans could be stale.
However, medium and light roast beans have not gone through the “second crack” when roasting and should be mostly dry. If your lighter roasts are oily as soon as you’ve brought them home, then you may have gotten an older batch, and your coffee won’t taste as fresh. However, if the coffee tastes fine, then the beans are okay, and no harm will come from continuing to use up the bag.
Oily Coffee Beans and Espresso Machines
As noted, there’s nothing wrong with drinking an oily dark roast. These coffee beans are coated in a naturally-released oil that usually doesn’t signify an older roast. However, there are times when you want to avoid an oily bean– even if it’s fresh.
If you have an espresso machine, then oily beans are something to avoid. Most espressos are medium or medium-dark because they create a rich crema and great flavor profile. You must use the freshest beans possible, especially if you’re using a medium-dark roast espresso.
The oil from coffee beans will build up over time in your espresso machine, gumming up important parts and causing expensive repairs. In the bean hopper, the oil will cause stickiness and discoloration and can eventually delay the bean’s flow into the hopper.
Grinders used to crush the beans will slowly be coated in oil, and the components will become sticky and dirty. They will be decreasingly effective, and the oil can build up into a gummy glue. This build-up will also alter the grind’s continuity, which results in less than optimal espresso shots.
In your home espresso machine, this build-up may happen so gradually that you don’t notice a huge disruption to your appliance. However, in a commercial setting, the amount of use that the espresso machine sees will increase the build-up rate and damage dramatically.
If you want to take care of your espresso machine, then be sure to stick to medium or medium-dark roasts at the darkest. Check that your beans are fresh and as dry as possible, and use espresso machine-specific cleaners that contain the specific components necessary to break down coffee oils without harming the expensive device.
Should I Wash My Coffee Beans if They Are Oily?
You may think that you can correct overly oily beans by washing them, but this is not true. If a bean is oily, it’s a sign of either the roast or the bean’s length of storage, and washing them will not alter these facts.
When dark roasts are oily, this is perfectly normal, and the oils are part of the coffee’s flavor profile. Washing these beans would change the taste of the coffee and the consistency of the grind. When medium and light roasts are oily, these beans are likely old and stale, and washing them won’t help save the actual beans’ flavor.
Not only will washing the beans help at all, but it will also be very difficult to do. Think of how difficult it can be to get bacon grease off of a frying pan; coffee beans would be just as stubborn, and you would not want to use soap to break down the grease either. Drinking coffee oil is much more pleasant than drinking dish soap!
Don’t trust everything you read about banishing oily coffee beans to the compost. While it’s sometimes true that oil is a bad sign on coffee beans, it’s not true all the time.
It is perfectly normal for dark roast beans to be oily. The oil is released during the long roasting process. However, medium and light roasts should be nearly dry. If these roasts are oily, you might have a stale bean on your hands.
- Espresso 101: What is Crema
- NCBI: Fats and Other Lipids
- Bean Poet: Oily Coffee Beans Explained
- Espresso Canada: How Oily Coffee Beans Can Ruin Your Espresso Machine and Coffee Taste
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