The quality and roasting of coffee beans make a huge difference in your drinking experience. Coffee beans are green when picked from the plant and change color, flavor, and texture during roasting. And you may have wondered why some coffee beans are oilier than others and what that means for your cup of coffee.
Some coffee beans are oilier than others because the natural oils of coffee beans are released during roasting and storage. If coffee beans go through a long roasting process, a chemical reaction causes the natural oils to release to the bean surface. This can also happen when storing coffee beans.
If you’ve ever wondered why there’s an oily substance on the surface of your coffee, then read further. This article will explore why some coffee beans are oilier than others and what impact (if any) it has on the taste.
How Do Coffee Beans Get Oily?
Not many people put much thought into the process of making coffee. They just grind the beans, scoop them into the machine, and hit brew. Then, quickly rush out of the door to head to work, sipping their coffee along the way.
But, there’s a science to pretty much everything.
And when it comes to the process of making coffee, from roasting to brewing, some reactions take place to create the taste and texture of your cup of joe.
Not all coffee tastes the same due to the type of coffee beans used, how they’re roasted, and how they’re brewed.
The Roasting Process
Coffee beans start out as green and dense seeds from coffee cherries. Once the beans are harvested, they undergo a roasting process that livens the rich and unique bean flavors. During this process, the moisture is forced out, and the structure of the bean begins to change.
The roasting temperature and time have a lot to do with the end result of your coffee flavor.
Very high temperatures are used during the coffee roasting process. The temperatures used are typically between 350℉ and 540℉ (177℃ and 282℃). The roasting time varies depending on the desired roast type and the temperature used.
The following chart represents a general reference of roast times at the temperature of 430°F (220°C) when roasting your beans in a coffee roaster:
|Color, Texture, and Flavor
|YellowishLight and airy textureRich flavors of the beanStrong aroma from the natural flavors
|Medium brownMore density due to the release of moistureMixture of natural and roasting flavors and aromaSome natural oils are released
|Dark brownSmall and dense textureBold, smokey roasting flavor and aromaOily
|Note: Times and temperatures can vary depending on your roaster. This is meant to be a general reference. Check your roaster for the suggested time and temperature to reach your desired roast level.
Roasting the beans at high temperatures eventually cause a cracking sound, indicating the internal shell is broken. The cracking sound is similar to the sound of popcorn popping. This is when the Maillard reaction comes into play and creates a sweet and caramelized taste from the sugars in the beans.
During the Maillard reaction, there’s a chemical reaction with amino acids and reducing sugars occurring between the temperatures of 280°F and 330°F (138°C and 166°C). The reaction creates browning from the caramelized sugars while releasing the flavor and aroma of the roasting process. As the beans roast longer, the natural flavoring dissipates, and the oils continue to release, along with more sugars, creating a different taste overall.
The Maillard reaction begins during the first crack of the roasting process. Roasting only up to this point is called the “Cinnamon Roast.”
This is just one of many types of roasts you can go for depending on your taste preference.
Light roasts are coffee beans roasted to the first crack to keep as much of the natural flavoring as possible. Medium roast is reached after the second crack has occurred. And dark roasts have the longest roasting times with more natural oils, caramelized sugars, and less natural flavor.
Storing Your Coffee Beans
With the rising prices of pretty much everything, you may be inclined to buy coffee in bulk when there’s a good deal. However, you should take into consideration that coffee beans can become oily and stale the longer they’re stored, waiting to be consumed.
It’s the natural process of the coffee bean to eventually crack on the inside after a certain period and release natural oils.
And as with most stored foods, factors that compromise freshness are the following:
So, keeping your coffee beans in an airtight container in a dark and cool room will help preserve them longer.
There is controversy among those in the coffee community about freezing beans to preserve their fresh state for longer storage life. But, if you decide to go that route, seal your beans with a vacuum sealer to store in the freezer. Vacuum sealers will remove all the air and create an airtight seal that will hold during storage.
Again, no matter how you store them, the natural oils will eventually release when stored for more than a few weeks.
As a result, its a lot better to buy coffee beans in small amounts, keep them in an airtight container and only grind what you’re immediately consuming to get the full effect of the bean’s freshness.
Do the Natural Oils in Coffee Beans Affect Taste?
The taste of your cup of coffee will be altered by the natural oils that are released. Longer roast times and high temperatures encourage the release of the natural oils. The sugars also undergo caramelization so you’ll taste more of the roasting flavor versus the natural bean flavor.
The longer the roast time, the darker the bean and deeper the flavour. Over time, it develops a bold, smokey, and sometimes chocolaty flavor.
Depending on the brand of coffee, some darker roasts almost taste burnt.
How Do Oily Beans Affect Grinders and Coffee Machines?
Oil sticks and creates a coating on anything it touches. So, using oily beans in your grinder and machines can cause build-up over time.
This oiliness makes cleaning your equipment regularly crucial to keep them sanitary and effective.
How Oily Coffee Beans Affect Your Grinder
The natural oil coating on the bean surface will cause the grounds to stick together and clump in your coffee grinder. The oil will also leave residue on the grinder walls and parts. To prevent build-up, clogging, and damage to your grinder, always clean it after use.
The small brush that comes with many grinders will help remove the build-up around the parts. You can also use an old toothbrush or a small paintbrush, as shown in the manual grinder cleaning video below.
Some people have even used rice in their burr grinder machine to help clean the parts.
Here’s a popular video on how to clean a burr grinder using rice:
Here’s another video explaining how to clean a manual grinder:
How Oily Coffee Beans Affect Your Machine
The oil from coffee beans can also compromise the condition of your coffee machine by creating oil residue and ground build-up. This is especially true for espresso machines since espresso is made from darker coffee beans with more oil.
A great coffee machine isn’t cheap, and espresso machines can be even more expensive. So, to keep them in top-working condition, you’ll need to ensure they are regularly cleaned and maintained.
Here’s a popular video explaining the effects of using oily beans in a Superautomatic Espresso Machine:
What Coffee Beans Are Less Oily?
Many have believed oily coffee beans result from staleness, but as you’ve already learned, that’s not entirely true. Most of the time, it’s due to the roasting time, with more natural oils released as the beans roast for longer.
While some don’t mind the oily texture of coffee beans, it can cause issues with your grinder and coffee machine from build-up.
So, to find less oily coffee beans, go for the light and medium roasts. These roasts will not only be less oily, but they’ll also pack more of the natural flavors and aroma offered by the beans.
Contrary to popular belief, dark roasts aren’t necessarily more potent or less strong than light and medium roasts. There is minimal change in the caffeine content during the roasting process.
However, the different roasts offer different flavors to your cup of joe.
The lighter the roast, the less oily your beans will be, with less of the smokey flavor from the caramelized sugars from longer roasts.
As previously mentioned, it’s better to buy the amount of coffee beans you can consume within two weeks because once they start going stale, you’ll notice the oily residue occurring on the surface of the beans.
Unfortunately, once they’ve become oily from staleness or if they’re bought oily, there’s no way to fix it without altering the taste of your coffee.
Oily coffee beans can create a different experience for a coffee lover, from the grinding to the brewing and the overall taste. Coffee beans naturally release their oils either during roasting or storage. The longer the beans roast, the more oily they’ll become, and the same applies to the length of storage.
The oily residue can cause issues with manual and machine grinders and automatic coffee and espresso machines. The oils and grounds build up along the walls and parts of these tools. Oily beans will also alter the taste, lessening the natural bean flavor.