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The Impact of Oily Coffee Beans on Espresso Machines: Cleaning Tips and Maintenance

Understanding Oily Coffee Beans

Coffee is a staple beverage for millions of people worldwide, and its popularity has grown over the years. You may have noticed that some coffee beans have a shiny, oily surface, while others lack this characteristic.

Have you ever wondered why this is so? In this article, we will explore the reasons why coffee beans become oily, the impact of oily beans on coffee characteristics, how to brew oily coffee at home, and the role of roasting in coffee bean oil production.

So, grab a cup of coffee, and let’s dive in.

Why Coffee Beans Become Oily

The roasting process is responsible for giving coffee beans their characteristic flavor and aroma. During roasting, coffee beans undergo a series of chemical changes, including the Maillard reaction, which is the interaction between amino acids and sugar.

This process leads to the formation of complex flavor compounds that determine the taste and aroma of the coffee. However, as the coffee beans continue to roast, they undergo a process called pyrolysis, where they start to break down and release oils.

The amount of oil that is released depends on the roast level the darker the roast, the more oil is produced. This explains why dark roasts are typically oilier than light roasts.

Oily Beans on Fresh vs. Old Coffee

When coffee beans are roasted, they undergo a degassing process, where they release CO2.

This process can take several days to a week after roasting. Freshly roasted coffee beans will typically have more CO2 and fewer oils on their surface.

However, as the coffee beans age, they continue to release CO2, leading to the migration of oils to the surface. Therefore, older coffee beans tend to be oilier than fresh coffee beans.

The impact of oily beans on Coffee Characteristics

The presence of oil on coffee beans can affect the flavor and quality of the coffee. For one, it affects the longevity of the coffee beans.

Oily beans tend to go rancid faster than non-oily beans, which can lead to a stale flavor. Oily beans can also cause issues with some coffee machines.

For instance, espresso machines can become clogged when using oily beans, leading to poor quality shots.

Brewing Oily Coffee at Home

Brewing oily coffee at home requires some adjustments to ensure you get the best flavor. For starters, you will want to use a coarser grind, which prevents the oils from clogging the coffee filter.

Additionally, you want to use a lower water temperature and a longer brewing time to extract the flavor fully. Finally, cold brew works well with oily beans, as they require less heat and a more extended extraction time.

Roasting and Coffee Bean Oil Production

The amount of oil produced during coffee roasting depends on the roast level. Dark roasts have more oil than light roasts because the beans are roasted for a longer time.

During the roasting process, the outer shell of the coffee bean becomes more porous, allowing the oils to ascent more easily. That is why the surface of darker roasts is more oily than light roasts.

The type of oil produced varies depending on the coffee bean variety, roast level, and country of origin. One of the primary types of oil found in coffee beans is lipid, which mainly consists of triacylglycerols, tocopherols, and sterols.

These oils have various health benefits and add to the flavor and aroma of the coffee.


Understanding oily coffee beans comes down to understanding the roasting process and its effects on coffee beans. The amount of oil produced depends on the roast level, age of the beans, and coffee bean variety, among other factors.

Oily beans can affect the flavor and quality of the coffee, but with the right brewing techniques, you can still enjoy a great tasting cup of coffee. Overall, oily coffee beans are a sign of well-roasted beans that have rich flavor compounds, making for a great cup of coffee.

Problems with Oily Coffee Beans

Coffee lovers know the value of quality coffee beans, which are key in producing delicious cups of coffee. One of the characteristics some coffee beans exhibit is their oily nature.

This oiliness gives a particular taste and aroma to the coffee. However, the oil that coats coffee beans also poses some challenges.

In this article, well discuss the problems with oily coffee beans, particularly their impact on coffee grinders, brew units, portafilters, and espresso machines.

Sticky Bean Hoppers and Machine Grinders

Storing freshly roasted oily beans in hoppers can result in bean hopper lids getting sticky, which can make it challenging to open the hopper. This happens because the oils coating the coffee beans produce a residue that sticks to the hopper wall and transport mechanism.

Also, the oil on the beans can lead to gumming up of grinder burrs and clogging of grinder chute or dosing chambers. This problem affects both commercial and home coffee grinders.

To keep the bean hoppers and grinders functioning optimally, it’s necessary to clean them regularly. A stiff bristle brush can help remove the stuck beans and oil residues.

Also, wipe inside the grinding chamber before installing the new coffee beans.

Clogging of Screens in Brew Units and Portafilters

Pouring oily beans into a coffee machine that has a built-in brew unit and portafilter can lead to clogging of the screens through which the coffee passes. Clogging is a common problem for oily beans, especially when the coffee maker is not cleaned after each use.

To avoid clogging, its essential to clean the brew unit and portafilter regularly and thoroughly. Removing the coffee oils that stick to the screens, valves, and rubber seals on the machine is necessary.

You can use a soft sponge or brush to clean up all areas, making sure to rinse multiple times to remove all soap residue.

Issues with the Espresso Machine

Maintaining your espresso machine with oily coffee beans is crucial to preserve its functionality. With time, oily beans can form a lacquer that coats the machine’s inner components, leading to poor steam, ruined shots, and machine failure.

The lacquer can cause problems like reduced pressure and clogging of the water tubes, resulting in leakages. To avoid issues with your espresso machine, it is essential to use proper cleaning techniques and products that can remove oily deposits.

Also, if you are not sure how to handle the cleaning process or face any problems, contact a licensed espresso machine service center.

Oily Coffee Beans and Espresso Machines

The quality of coffee contains compounds that make it delicious and irresistible. However, oily beans can cause problems with espresso machines, especially in commercial settings where the machine runs all day.

Oily beans produce more residue and lead to increased machine maintenance, which can impact the quality of the coffee.

Effect of Oily Beans on Espresso Taste

Oily beans brewed in an espresso machine can lead to over-extraction and a bitter-tasting coffee. The oil coats the coffee grounds, which can result in unevenly extracted shots that don’t taste pleasant.

As the espresso machine heats up, the oils on the beans can also become rancid, leading to an odd taste in the espresso.

Impact of Oil on the Espresso Machine

The oil produced by oily coffee beans can lead to a whole set of issues on the espresso machine. Over time, the oil can accumulate in the brew group, water lines, and in the coffee grinder, limiting the flow of water.

This can cause the machine to struggle to maintain optimal brewing temperatures and potential issues in delivering espresso shots.

How to Handle Exceptionally Oily Beans

If you stumble upon oily coffee beans that produce lacquer on your espresso machine components, avoidance of use is the primary solution. Discard the oily beans or use another method to brew them.

When brewing oily beans, clean your espresso machine more frequently than usual by backflushing, descaling, and desolventizing it. Its also essential to use cleaning products specifically designed for the coffee machine.

These products enable you to dissolve stubborn oily residues and conduct a thorough and complete clean-out of the machine.

Final Thoughts

The challenges with oily coffee beans are a way of life for coffee machines and coffee lovers. The oil produced during roasting is a result of the complex chemical changes that create the coffee’s flavor.

However, the oil produced can lead to clogging and machine issues. Regular maintenance, cleaning, and using quality and properly stored coffee beans can enhance the espresso-making experience.

Frequently Asked Questions

Coffee lovers have many questions about oily coffee beans. As a frequently discussed topic, its important to provide answers to some of the common questions people ask, particularly regarding the interaction of oily coffee beans with espresso machines, changes in beans during roasting, drying process and oil content in dark roast, among other topics.

Use of Oily Coffee Beans with Espresso Machines

Can I use oily coffee beans with my espresso machine? Yes, you can.

However, you should be aware that oily coffee beans can cause issues; clogging problems, difficulty in cleaning and maintenance, and producing bitter or rancid coffee. Oily beans can also leave residue in the grinder, portafilters, and brew units.

Regular maintenance may help prolong the life of the espresso machine and reduce the risks.

Changes in Oily Beans during Roasting

What happens to oily coffee beans during roasting? Oily beans undergo complex chemical changes as the roasting process progresses.

First, moisture escapes from the roasted coffee beans, then cellulose fibers start breaking down, and as the temperature increases, the beans turn tan or light brown. As further roasting continues, the outer shell of the coffee beans gradually becomes porous, releasing oils that coat the surface of the beans.

The beans then turn dark until they transform into charcoal.

Drying of Oily Coffee Beans

How do you dry oily coffee beans? Beans that have some moisture but produce natural oil can take much longer when it comes to the drying process.

After roasting, coffee beans have to cool to room temperature before packaging. To dry oily coffee beans correctly, spread them across a flat surface, allowing them to dry evenly.

Its crucial to move them around every few hours for uniform drying. Never stack oily coffee beans on top of one another to avoid trapping moisture between them.

Oil Content in Dark Beans and Dark Roasts

Do dark roasted beans contain more oil than light roasted beans? Yes, they do.

As the beans roast, the oils in the beans migrate to the surface, giving it a shiny oily appearance. Dark roasted beans contain more oil compared to light roast due to the extended roasting time and higher temperatures used to roast them.

Type of Oil Present in Coffee Beans

What type of oil is present in coffee beans? Coffee beans contain various types of oil, including fatty acids, lipids, tocopherols, and sterols.

Lipids are the primary fats present in coffee beans – Triacylglycerols, the main component of coffee oil, make up over 80% of the lipids found in coffee beans. Tocopherols function as antioxidants, providing protection against cellular damage, while sterols are similar to cholesterol.

Clogging of Grinder by Oily Beans

Why do oily beans clog the grinder? The oils present in the coffee beans can stick to the interior of the burrs, impeding the grinding process.

Over time, the machines grinder can become gummed up, which can cause issues with grinding the beans and dispensing grounds or tamping. When using oily beans, it’s recommended to clean the grinder regularly by running a small amount of rice or bread in the machine, which helps break the oil residue.

Final Thoughts

Several challenges come with using oily coffee beans, but with the right approach, coffee lovers can have a seamless experience brewing using them. From properly drying to roasting and ensuring regular maintenance for the coffee machine, there is much to consider.

Through awareness, coffee aficionados can take the necessary steps to optimize oily bean experience with their espresso machine, making sure to get the best out of every cup. In conclusion, understanding the nature of oily coffee beans and their impact on espresso machines is crucial for coffee enthusiasts and professionals alike.

Oily beans can lead to clogging, maintenance issues, and potential flavor problems when used with espresso machines. It is important to take preventive measures such as regular cleaning, using appropriate cleaning products, and avoiding excessively oily beans to maintain the functionality and flavor quality of the espresso machine.

By being knowledgeable and proactive in handling oily beans, coffee lovers can continue to enjoy the rich and aromatic experience that quality coffee provides. So, remember to clean, maintain, and choose your beans wisely for a truly exceptional cup of coffee.

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