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Oily Coffee Beans: An Explainer on Why It Happens
Is oily coffee a good thing or a sign of bad coffee? Let’s break down the science!
Published January 7, 2022
Asharita D'Silva
Coffee experts@Era of We
The next time you go out to buy whole coffee beans, take some time and notice if the beans are oily. Most of the time, you’ll find dry beans but every once in a while, you’ll come across some dark and shiny beans. This sheen is characteristic of oily coffee beans and the debate over oily coffee can really divide the coffee community. So, is oily coffee good or bad? Let’s take a look at the issue and I’ll let you decide.
Why Are Some Coffee Beans Oily?
Oily coffee beans are all about chemistry. As heat is applied during roasting, the coffee bean begins to split and release carbon dioxide and other compounds present inside the beans. This reacts with the air to produce an oily sheen. The longer the beans are roasted, the more likely they are to be oily.
You need to remember that coffee beans are essentially seeds, which means they’re packed with amino acids, carbohydrates, and lipids. The release of these lipids, whether through roasting or slowly over time, gives you oily coffee beans. Does this mean oily coffee beans are bad or good? It’s all relative. Dark oily coffee beans could be oily because it’s been freshly roasted, which would be good. But a light-roasted coffee with an oily sheen? That could mean it’s going stale.
Many coffee lovers consider oily coffee to be inherently bad- after all, those oils contain a lot of flavor and they start to oxidize and degrade as soon as they come in contact with air. Dark oily coffee beans like an Italian or French roast may also taste smoky or like charcoal, something not everyone can stomach. And if you see light or medium roasts with an oily sheen, stay away- it's probably going stale.
Are Oily Coffee Beans Bad?
Now we know that oily coffee beans are most commonly because of a longer roasting time, so no, it’s not always a bad thing. If you like darker roasts, then oily coffee is an expected effect of the roasting process. However, many baristas and other coffee professionals prefer not to work with darker roasts or oily coffee since by roasting for so long, the natural flavors in the coffee are completely changed. It’s almost seen like you’re roasting away all the flavor by letting the coffee oils escape to the surface.
Dark roasts gained popularity as the demand for coffee rose. It became convenient to take sub-par coffee and roast it to a dark roast in order to disguise the taste. Consumers would either only taste the smokiness of the roasting process or it would be used to make espresso, which naturally brings out strong and oily flavors. Certain Brazilian and Colombian coffees do well as dark roasts, but for the most part, chain cafes would use dark roasts the most in order to push cheaper coffee.
Despite being popular for espressos, dark oily coffee beans can actually be harmful to automatic espresso machines. The oil can collect in the machine and grinder causing the components to jam. If the buildup is left unchecked, it can stop the machine entirely. This is most commonly seen in smaller machines, like those used in local cafes and at home.
Non-Oily Coffee Beans: Is It Possible?
Of course! As we’ve been discussing, oily beans are the result of a long roasting interval. If you prefer non-oily coffee beans, simply choose a light or medium roast which has a shorter roasting interval, meaning the oils don’t reach the surface of the bean. Choose the freshest beans while you’re at it since oiliness can also result from beans begin left out too long and going stale.
How To Avoid Oily Coffee
Here are a few tips on how to avoid oily coffee:
1. Pick light or medium roasts instead of dark roasted coffee. Dark roasts are inherently oilier.
2. Choose the freshest beans. Coffee beans can get oily when exposed to air for too long. This makes it go stale.
3. Avoid decaf coffee, as this tends to be oily in general.
Roast profiles are a matter of personal preference, so some people may actually like oily coffee. However, if you use an espresso machine, it’s always a good idea to switch to non-oily coffee beans so that you don’t ruin the machine. Overall, oily beans can mask the natural flavors of the coffee so you could miss out on some unique flavor profiles if you select dark oily coffee beans. There’s really no way to get rid of the oil once it’s released from the bean, so be careful about the roasts you pick. And if you like oily coffee, always check the roasting date so that you know the coffee is not oily because of time. Oily coffee may not always be bad, but stale oily coffee is never a good thing!
About the author
Asharita D'Silva
Join me in discovering the wonderful world of coffee! As a writer, coffee is my fuel and newfound passion. I love writing about new coffees, sustainability, and coffee culture around the world. I'm always discovering new things about coffee and the industry, which I share with the great community here at Era Of We.
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