If you are a coffee lover and like to grind the beans yourself, you might have noticed that some beans are often oily. There’s debate about whether it’s good or bad for the beans to be oily, but the question remains: why are some coffee beans oily?
Seeing oil on the surface of roasted coffee beans is normal, as it’s a normal byproduct of roasting. Beans have oils and gases inside them, and roasting releases them outside. So the longer you roast the beans, the darker they will get and the more oil they’ll dispense.
The type of bean also plays a significant part in how oily the beans will be after roasting. For instance, Robusta beans contain much more oil and fat than Arabica. Generally, though, seeing oil on beans is a good sign – it means they are freshly roasted. The longer they sit, the less oil they have on the surface.
What Causes Oily Coffee Beans?
Oily coffee beans are a common occurrence when coffee is roasted. To understand better how and why oil appears on the surface of your roasted beans, I’ll walk you through the roasting process.
Coffee beans are green at the beginning of the process. When you crack up the heat, the drying period starts, turning the beans yellow. Continuing the roast further will gradually turn the coffee brown, which is when the first crack happens. After that, the walls inside the bean’s core cells crack and start letting out gases and oil from them.
You can stop here and get a light roast. It doesn’t have the time to release a considerable amount of oil by then, so an oily surface is rarely seen on lightly roasted beans. They also have more caffeine than more thoroughly roasted beans, although they produce a much milder taste and fragrance.
If you continue roasting, you’ll progress to a medium roast. The color of the beans gets a darker shade of brown, and an oily surface may be present a few days after roasting and throughout the next three weeks or so.
I love a medium roast the most because it’s the most balanced – a decent amount of caffeine while releasing enough fragrance and the characteristic bitter taste of coffee. However, you avoid that pungent, smoky taste that comes with the final stage – the dark roast.
One would think that dark roasted beans contain the most caffeine because they have the most robust taste. The reality is the opposite, though. Due to the longer roasting process, more oils, gases, and nutrients get extracted from the beans, including caffeine. That’s why dark roasted beans are usually the oiliest, even immediately after roasting.
The large amount of oil on the beans creates the perfect crema on espresso, which is why some baristas use it, but I don’t recommend it in any way. When using dark roast beans for espresso, you’re getting the smoke, burnt fragrance instead of authentic, delicate coffee flavor. You’ll know what I’m talking about when you try a medium-roast espresso.
To conclude, roasting causes oil on the beans. The lighter the roast, the less oil the beans produce. Avoid dark roast beans that aren’t oily because not only are they smoked out of caffeine and true coffee taste, but no oil also means they aren’t that fresh. Some say that ground coffee can sit for two years, but It loses its best qualities after a month.
So, every coffee bean will be at least a bit oily. But, one more factor comes into play – the type of beans you use. Robusta beans are commonly used from creamier, denser types of coffee because they are “fatter,” producing more oil. Arabica is the most common type, though, with less oil and longer shelf life.
Are Oily Coffee Beans Good or Bad?
I won’t say straightforwardly that oily coffee beans are good, but I will tell you this: they are better than completely non-oily beans. If there’s oil on the beans, it means they are still fresh. After three to four weeks, the oil evaporates on dark roasted beans and even sooner on lighter roasts (because they release less oil, to begin with).
If you see a dark roast bean with no oil on it, skip the coffee break. It means it’s stale and probably tastes like that, too. That doesn’t mean it will taste great if the beans are oily, though, especially on dark roasts. Mass producers like Starbucks and other coffee shops with massive traffic look to make their business as profitable as possible.
Their beverages tend to have many other ingredients, so they buy cheaper coffee beans and then dark roast them to enhance the taste as much as possible. Don’t get me wrong, I love their coffee, but if you want a finer taste of authentic coffee, go for an old-school, traditional coffee shop.
Therefore, oily beans indicate fresh coffee, but too much oil means a lot of bitterness in your coffee. Aim for a medium roast if you want the perfect balance between taste and strength.
Oily Coffee Beans – What Does It Mean to You?
So, you got freshly roasted beans, and you noticed they are pretty oily – what does that mean to you?
First of all, it means the taste will be a lot stronger and bitter. Depending on the roast level, it will also influence the density of your coffee after brewing. But, when it comes to cleaning your appliances or cups, that’s where you’ll feel the most significant difference.
I have a fantastic espresso maker at home. It’s not an industrial espresso machine that you could mass-use in a coffee shop, but a high-quality domestic version of it. So, a friend recently recommended a new brand of coffee beans to me. I got it, and the beans were somewhere between medium and dark roasted but had a lot of oil on them.
Indeed, it was fine coffee all around: great texture, incredible aroma, and crema to die for. However, it took only one bag to clog the grinder in my espresso maker entirely. What is more, it was tough to clean, so I had to say bye-bye to my newfound brand.
Oily beans indicate a fresh roast but dictate your brew’s taste, texture, and overall quality later. Also, it can be a pain to clean your appliances after regular use of oily beans, so it’s a matter of finding the perfect middle ground.
Oil and Coffee Roasts
By now, it should be clear that the roast level will heavily determine the amount of oil on the beans. If you’re still unsure about what properties each roast level has, here’s a quick reference guide you can always turn to.
The lightest color of the beans, usually being the least oily. While the short roast time keeps the most caffeine inside the beans, it also keeps the most aroma and taste trapped too, meaning a milder coffee when brewed. It has the shortest shelf life, too.
The medium roast is a balance between the strength in taste and the strength in caffeine. It has a moderate amount of oil on the beans, giving a rich crema and extracting the best qualities of the coffee but not allowing the smoky bitterness to kick in if the beans are burnt further.
The dark roast is also the oiliest. While it tastes the strongest, it has the least caffeine out of all three roast types. The long roasting time extracts it out of the beans, but the oil gives the most crema, where the bitter taste and intense aroma lie. If a dark roast isn’t oily, it means it has to be stale and not freshly roasted.