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Does oil on coffee beans affect the taste?

At a certain stage in the roasting process, coffee beans give off oil naturally. This means that if you see coffee beans sitting in a hopper and they are oily, it is likely that they have a dark roast and have spent a long time being roasted.

Does this really affect the taste? Should you stay away from oily coffee beans or is it something that you may enjoy?

Before we get into some of the technicalities of coffee and coffee beans, and the roasting process that helps to create the coffee we all love, you should understand that it has a lot of nuance to it.

Coffee beans that are oily may be one person’s favourite, while another would never even consider touching them. And that’s okay!

Coffee beans
Coffee beans

Photo: pexles.com

The roasting process

A little bit of an understanding of the roasting process can go a long way. It can get complicated, but to boil it down to the very basics, there is a “first crack” and a “second crack” which are to do with the bean shell opening to allow some of the compounds inside to come out, including gas.

This usually happens at the “second crack” and you may also hear oil sizzle, a bit like in a hot pan. This is because the oil within the bean has come closer to the surface and therefore it is exposed to heat, and some of the oil can even leak.

The oil formed during the roasting process is much more likely to be visible if you have gone for a dark roast, taking longer over roasting. The level of roast is definitely linked to the oil, and it is more likely you’ll get an oily result with a dark roast, but actually the light and medium roasts can contain plenty of oil, and once ground this can also get released.

Roast profile and taste

The level of coffee bean roast makes a huge difference to the taste, but is the oil the culprit?

Well, that depends on your opinion. This is something of a “chicken and egg” situation, but in general, the more oil you can see, the more likely it is that there is a dark, bitter taste to your coffee.

Lighter roasts tend to keep the oil within the bean and this can give you a much sweeter and more subtle taste, rather than the overpowering flavour that we can sometimes see when it comes to heavy, dark roasts.

Darker, oily roasts may also destroy some of the natural flavours of the coffee, and take away the subtle differences in the varieties of coffee you can buy. If you are going to purchase a really high-quality, single origin coffee, then a light roast can be a good way to ensure you are getting a true reflection of the taste.

In dark roasts, the coffee oils that have so much flavour inside have come up and out of the bean and reacted with oxygen, this leads to a dark and bitter taste.

Coffee beans
Coffee beans

Photo: pexles.com

Oily beans can be stale beans

This isn’t always the case, but generally, dark roasts with lots of oil around them tend to get even more oily and they can also oxidise much quicker. This way there won’t be much oil that remains in the beans when it is time to use them, and this means the flavour has gone.

They probably won’t do you any harm, but they can definitely lose a lot of what makes coffee great. Basically, by going to a further level of roasting the beans have already started to oxidise, and this can mean a much quicker process of going stale. This is certainly not something that you will want for your beans in an ideal world.

If you are going to go for darker beans with a heavy roast, then you should make sure you are going to use the beans quickly enough that they don’t have time to go stale.


Coffee is always a matter of personal preference. A lot of people actually settle on something that is in the middle, and a medium roast can make sure you’ve got freshness and flavour in your coffee rather than settling for something either too oily, or that hasn’t really had its flavours unleashed in the roasting process.

Overly oily beans definitely come with a number of downsides, and they can even put extra strain on your equipment. For instance, getting a lot of oil on a grinder can quickly degrade the quality or mean you need to clean it much more so that you don’t get blockages or dirt building up inside.

Everyone has their own opinions when it comes to coffee beans, and the beauty of coffee is that there is no right or wrong. Asking someone’s favourite type of coffee is like asking what kind of food they like, everyone will have their own answer.

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