How To Avoid Oily Coffee Beans

Oil on the surface of coffee beans is normal, especially in beans that are darkly roasted. But some people might not enjoy the texture created by oily coffee beans, and high levels of oil can even cause mechanical issues in bean-to-cup coffee machines. Beans that are too oily will not taste good in coffee, either.

When coffee beans are roasted, oils within the beans are released. This results in coffee beans with an oily surface. The longer beans are roasted for, the more oils come to the surface and the oilier the beans will be. The roasting process also causes coffee beans to lose carbon dioxide, which reacts with oxygen in the air and forms oil on the surface of the bean.

Even lightly roasted beans can become oily if mistakes are made during the roasting process. Oil migration is usually the result of moisture changes that occur during roasting to the outer and inner layers of the bean. Common mistakes include not heating the roasting drum enough or overheating it.

Roasters trying to avoid oily coffee beans can opt for a lower roast level. Medium roast coffee beans are usually significantly less oily than dark roast coffee beans, although it’s also possible to roast darker beans without creating too much oiliness.

Other factors that can cause oily beans include storage methods, humidity, and temperature. Beans that are stored for a long time, especially beans stored in humid or warm conditions, will become oily. It’s important to store coffee beans in a cool, dark environment where they will stay dry and fresh.

Coffee beans are oily because coffee beans are composed partly of fats and oils. Coffee beans are actually the seeds of the coffee fruit, and these seeds must contain everything needed to grow a fruit, which includes the fats in coffee oil.

Most coffee beans are actually composed of between 7 and 17% fat . Some coffee beans are naturally more oily than others. Continental, Java, and Old Brown coffee beans are all examples of beans that have high natural oil levels.

Unroasted coffee beans are very dense. As they’re roasted, they become lighter. This is why light roasted beans are denser and heavier than dark roasted beans. Moisture from inside the bean evaporates during the roasting process, releasing carbon dioxide and producing a thin, oily film on the surface of the bean.

Because dark roast beans are roasted for longer than light and medium roast beans, more oils migrate to the surface of the bean during the roasting process. Oiliness is not always a sign of quality; often, it simply indicates roast level.

Coffee beans also become more oily over time, even when they’re stored properly. One study demonstrated that both Arabica and Robusta coffee beans became significantly more oily when stored for nine months or longer.

Often, light roast beans will have a dry, matt appearance while dark roast beans will have a shiny, oily surface. The longer roasting process involved in dark roast beans will draw more oils to the surface of the bean. If your coffee beans are shiny, it’s likely caused by oil on the surface of the bean.

Oily coffee beans are not necessarily better than dry beans, unless the coffee beans are dry because they’re old. Old coffee beans can become dry if stored for too long, because oils will seep out of the beans over time and slowly evaporate. Coffee beans stored in warm, humid environments can also become too oily.

Oiliness is closely related to roast level. Most people think that shiny coffee beans are a signifier of freshness. While oiliness can indicate freshness, it’s not the case that dry beans are necessarily stale. They could just be very lightly roasted.

The coffee roasting process can lead to oily surfaces because natural fats and oils are drawn out of the coffee beans during roasting. CO2, or carbon dioxide, also seeps out of coffee beans during the roasting process, and this reacts with oxygen in the air and creates more oil on the surface of the bean.

This is why darker roasted coffee beans, which are roasted for longer at higher temperatures, are oilier than light roasted beans. The longer roasting process draws more oil and CO2 from coffee beans and creates a bean with a shinier texture. Dark roast coffee beans taste different to light roast beans, but neither is objectively better than the other.

Oily coffee beans can present challenges during grinding, and they can also be difficult for coffee machines to handle. The oil in very oily coffee beans can even clog certain mechanisms in bean-to-cup coffee machines.

It’s important to dismantle all grinders properly between use and clean them thoroughly. This prevents residue from oily beans from building up and causing mechanical errors during grinding.

Grinding oily coffee beans with a blade grinder can be very difficult. The oil in the coffee beans can cause clumps of grounds to form, creating hard lumps that blade grinders will struggle to cut through. This creates inconsistencies in grind size and may clog the blade grinder.

However, even burr grinders can be clogged by oily coffee beans. Some burr grinders are designed for use with oily beans; these may offer better performance than a standard grinder, especially if you enjoy making coffee with very oily, dark roasted beans.

Oiliness can also impact the flavor, texture, and longevity of coffee beans. Oily coffee beans won’t stay fresh for as long as dryer beans, because oils go stale and rancid more quickly than dry produce. Rancid coffee beans will produce unpleasant, bitter-tasting coffee.

Coffee beans that are less oily will produce coffees with a smoother, more consistent taste and texture profile. However, if you want to enjoy the classic taste of dark roasted coffee, you’ll have to put up with at least some oiliness. Medium roast beans can offer a balance between full body and taste without the oiliness of dark roasts.

Yes, it’s possible to dry oily coffee beans to reduce oil levels across a batch of roasted beans. You can try various methods to dry out oily coffee beans if you want to make them easier to grind, or if you want to change the taste of your coffees.

Mixing oily coffee beans with dry coffee beans is one way to reduce oil levels. You can do this by, for example, mixing oily dark roast beans with dry light roast coffee beans. Leaving a mixture of the two together in an airtight container will allow the lighter roast beans to soak up some of the oils from the darker roast beans.

Another way to dry out oily coffee beans is baking oily beans in the oven. Spread oily coffee beans across a baking sheet and bake them at around 200F just for a few minutes. Remove them from the oven as soon as they reach the level of oiliness that you’re looking for.

You can also dry out oily coffee beans by air drying them at room temperature. This method takes a little longer, and it’s important not to leave coffee beans out for too long or they could go stale and lose a lot of their flavor. However, with this method you’re not risking scorching or burning your beans.

Finally, never try drying out coffee beans by rinsing them under water or patting the oil off them with a paper towel or napkin. Both of these methods will dry your beans out and strip them of their natural flavors and aromas, resulting in bland, tasteless coffee.

You can remove the oil from coffee beans after roasting by oven baking, air drying, or mixing oily beans with dry beans. These techniques can balance out oiliness in very oily beans without impacting flavor and aroma content.

It’s also important to store coffee beans correctly to avoid them becoming more oily over time. Always store freshly roasted coffee beans in an airtight container in a cool, dark place. Coffee beans should always be stored in a dry area, away from any moisture or humidity that could cause the beans to sweat and become more damp or oily.

Whole beans will stay fresh for longer than pre-ground beans. The smaller surface area of whole beans compared to ground beans slows down processes like oxidation and maximizes the lifespan of your beans.

By choosing less oily varieties of beans that have been light or medium roasted, you can minimize bean oiliness. Storing your beans properly - and using appropriate drying techniques when necessary - can further help to keep oil levels low.

You can prevent coffee beans from getting oily over time by storing them properly and taking steps to reduce oiliness when necessary. Consuming coffee beans when they’re fresh will also prevent oiliness from forming.

Coffee beans can become more oily over time if they’re not stored in an appropriate way. If you store coffee beans somewhere warm or humid, this can draw oils out of the beans and increase oiliness. It’s best to store coffee beans in an airtight container in a cool, dark place, and use them as soon as possible after opening to prevent oiliness from building up.

Oiliness in coffee beans occurs slowly over time, no matter how well your coffee beans are stored. It’s usually advisable to consume freshly roasted coffee beans within around three weeks of their roast date. As well as enjoying all of the fresh flavors of your coffee beans, this will stop them from sitting long enough to become more oily.

Oiliness isn’t always something to be avoided. Experiment with different coffee beans, brewing methods, roast profiles, and grind sizes to find combinations that you enjoy. While some oily beans might make your coffee taste too bitter, other coffees brewed with oily beans will carry bold, complex flavors.