How Coffee Beans Are Decaffeinated: A Complete Guide

“Decaf coffee is weak,” “it’s just regular coffee with a decaf label,” and “decaf coffee has more caffeine than regular coffee” are among the things I have heard about decaf beans and the coffee they produce. Decaf coffee is produced through a predictable method that ensures the removal of at least 95% of the caffeine.

Coffee beans are decaffeinated by boiling green coffee in water, removing all the coffee extract, and adding methyl chloride. The solution is heated, so the caffeine evaporates, and then dehydrated beans are put back in the solution so they can soak back the coffee flavor and oils.

In this article, you will learn about the process, its alternatives, and what happens at each one of the following stages.

  • Coffee cherries are collected
  • The cherries are dried 
  • Parchment coffee is removed from the cherries
  • The green coffee (inner bean) is removed from the pit
  • The green coffee is boiled in water
  • The water is decaffeinated with methyl chloride
  • The coffee beans are added to the decaffeinated extract
  • The beans are packaged and shipped
  • Roasting of the coffee is done before retail packaging

Step 1 – Coffee Fruit Is Harvested

The first step in decaffeinating coffee beans is collecting them. This starts with getting enough coffee berries. The pits of these berries are the coffee beans we are so familiar with. When coffee fruit is removed from its respective plant, it isn’t immediately hacked to extract the beans. That’s because the most stable a coffee bean can be is inside the berry.

So the initial step features harvesting with emphasis on fruit ripeness. This entails strip-picking the entire batch of coffee cherries by ‘stripping’ the branch. Then, the cherries are sorted to separate the ripe ones from the ones that don’t seem to be in ideal condition (i.e., aren’t the right color). 

Getting the berries on time means the bean has the ideal coffee flavor, but there is a problem! The fruit itself can spoil and impact the bean’s health. This is where the second step is executed almost immediately.

Step 2 – The Fruit Is Dried to Prevent Spoilage

Once the coffee berries are removed and sorted for maximum flavor, they are dried on large sheets, so they are semi-wet. The drying process puts the cherries in a drastically different environment from what they’re used to. Coffee plants are raised in shaded nurseries while their cherries are dried in the sub. The berries are turned by hand (using a stick), so all sides get even exposure to the sun.

Step 3 – The Core (Parchment Coffee) Is Removed From the Fruit

The entire coffee fruit is not shipped by the barrel because, despite being sun-dried, the cherries take up significant transport space. In some instances, the beans are removed from the cherries and then dried. In most cases, though, the entire fruit is dried so the rind can be removed by a machine. 

The beans that are extracted are not roast-ready because they have a protective layer over them. This is called parchment coffee. It can be best imagined as a pistachio shell over a coffee bean instead of actual pistachio. This shell is not removed immediately because it protects the coffee beans from the environment and doesn’t take up enough space to affect shipping costs.

Step 2 – Parchment Coffee Is Transported to the Treatment Facility

This stage is a pretty straightforward one, where the beans (still inside the protective pits) are transported to the treating facility. The “treatment” for regular coffee beans stays the same up until the extraction phase. After that, the process is quite different for decaf beans. The transport stage starts with the parchment being dumped into jute bags.

These bags have become an aesthetic in the coffee culture, and coffee bean packets at Starbucks are often displayed in similar bags. The jute bags full of parchment coffee are thrown into the back of trucks and transported to the ‘shipping point.’

For coffee beans coming via road, the shipping point is the facility where the parchment coffee is consolidated from multiple pickup trucks into a large container. In case the coffee crosses a body of water, the beans are loaded into a cargo container that is moved onto a cargo ship.

This step could be different in theory if the coffee farms were closer to the treating facilities. If America got its coffee from American farms, the shipping point would be unnecessary, and trucks could carry parchment directly from the farm to the treatment plant. 

The same would be true if the shelling facility were located inside a coffee-rich country like Columbia. However, all the bulk buyers of coffee beans like the milling step to be their responsibility. The steps prior to this are the responsibility of the wholesaler.

Step 3 – Coffee Beans Are Hulled

Here the regular coffee beans get a different treatment from the decaf ones. While regular coffee beans are milled, size-sorted, graded, and shipped for roasting, decaf ones are milled at a facility that is capable of decaffeinating the batch.

Coffee beans are decaffeinated at the green coffee stage, which follows hulling and polishing. The hulling stage is done by a machine that is capable of removing every layer that covers a coffee bean. In case the coffee beans are shipped within the dried cherries, the machine removes the rind as well as the pulp and the inner layer. 

For coffee pits removed from the fruit, the machine tears away the single layer that surrounds the bean. Either way, the resulting coffee bean is a green one, which contributes to the title ‘green coffee.’

Step 4 – Green Coffee Is Prepared for Decaffeination

Green coffee beans are already leaning towards decaffeination because they’re exposed to the elements. Where the producers of regular coffee beans have to worry about the temperature and its effect on the beans’ ability to hold their essence, decaf bean sellers don’t have to worry about much. The decaffeination is done at a nearby facility or at the same processing location where the beans are hulled.

There are four ways coffee can get decaffeinated. Here is a gist of the possibilities:

Decaffeination methodDescriptionHow often the process is used
Using a direct solventCoffee beans are exposed to an ethyl acetate solution for an average of 10 hours, then steamed to remove the solution.10% of the time. This method is popular because it is considered a natural decaffeination method.
Using an indirect solventCoffee beans are soaked in boiling water to remove their water-soluble contents. The caffeine is removed from the liquid using chemicals. The beans are reintroduced to the water to soak up the remaining flavor.80% of the time. This is the most widely used decaffeination method.
Through a supercritical carbon dioxide processHighly pressurized carbon dioxide is pushed through a chamber carrying green coffee, and the caffeine absorbed by the gas is removed by activated charcoal.5% of the time. This method is quite expensive and requires 3 to 6 extra hours per batch.
With the swiss water processJust like the indirect solvent method but features water as the main solvent and activated charcoal as the caffeine removing agent.5% of the time. While this method is popular among the organic coffee businesses, the small number of operators in that space account for the “cleanest decaffeination method” being used less frequently.

Because we are following the beans’ journey in chronological order, it is important to pick one of these methods and continue describing the steps moving forward. For the purpose of this post, we will continue with the most widely used method: indirect solvent decaffeination.

Step 5 – Green Coffee Is Soaked in Boiling Water

At this stage, the coffee beans are essentially brewed to remove their “water-soluble” contents. These contents include coffee acids, flavor, and caffeine. The beans are decaf in a sense at this stage, but they are also free of oils and coffee acids. 

If these beans are dried and roasted, they produce coffee that tastes like boiled water. It is essential to “put back” the oils and the coffee acids into the beans. But the obstacle is the fact that caffeine is mixed with oils and acids.

Step 6 – Green Coffee Extract Is Decaffeinated With Methyl Chloride

Methyl chloride is added to separate the caffeine from the rest of the green coffee extract. This chemical essentially latches onto the caffeine and makes it ‘steamable.’ When the extract is boiled after adding methyl chloride, the caffeine evaporates alongside the methyl chloride. This leaves behind coffee oils and flavors with as little as 0.01% caffeine (in some cases)

Step 7 – Coffee Beans Are Reintroduced to the Green Coffee Extract

Finally, to add coffee ‘flavor’ back to the ‘technically decaf’ beans, the green coffee is added back to the solution. The beans are left to soak in the juices and, because they have been cured out of any liquid content, absorb the extract. It takes a few hours for the beans to have enough liquid content to be safely dried without losing flavor.

Step 8 – Green Coffee Is Packaged and Shipped

This is the step where green coffee beans are packaged for individual retailers to remarker or are bagged by the barrel for wholesale. In some cases, the beans are roasted soon after and sent directly to warehouses for retail, but because roasting coffee requires different expertise, it is more feasible to simply decaffeinate beans and sell them in their green state.

Step 9 – Green Coffee Is Roasted

Finally, the coffee beans go through the stage where they go from an unrecognizable green to a familiar brown/black color we all associate with coffee. There are three main roast settings: light roast, medium roast, and dark roast. 

While novices assume the darker coffee has more caffeine, you can see that the opposite is the case. The more a bean is roasted, the more caffeine it loses. However, with decaf beans, the only thing roasting affects is the coffee’s taste. Here are the roasting options and their effects.

Coffee RoastEffect of flavor
Light roast The coffee tastes mellow and sweet, with a more complex flavor. There is some bitterness in the profile because of the acidic soils. You can even tell the region of the beans and assess their processing conditions based on the desired taste.
Medium RoastThis is the sweetest roast of coffee as it balances the removal of acidic oils with avoiding the charring of its inner contents. It is also the most bought and used roast in decaf and regular coffee.
Dark RoastIt has a chocolatey flavor with an emphasis on bitterness. While most of the bitter acids leave the beans because of extended exposure to high temperatures, the beans produce bitter coffee because they are essentially charred. 

Alternative Decaffeinating Methods

Having covered the main method of coffee decaffeination in detail, let’s go over the alternative methods in a little more detail. This section will explore the three other ways in which green coffee is decaffeinated.

The Direct Solvent Method

You may have noticed that boiling coffee to remove its ‘juices’ and then decaffeinating the extract before putting the beans back in the juice seems a little long-winded. The direct solvent method cuts the process shorter with the following steps:

  • Beans are soaked until soft 
  • Ethyl acetate solution is added to the water
  • The beans soak for 10 hours
  • The rest of the solution is evaporated by steaming.

The Activated Charcoal Method

Activated charcoal can also remove caffeine from a liquid and is used in 2 ways for decaffeination. The carbon dioxide method entails pressurizing CO2 until it starts behaving like a liquid despite being gaseous and running it through the beans to extract their contents. The ‘liquid’ is then blown over activated charcoal and liquified around the coffee beans. Water can also be used for the same process but takes a lot longer.

Final Thoughts

Decaffeinating coffee beans is a lengthy process with industry-set practices. Attempts to decaf at home are less likely to be successful because any process that extracts caffeine also removes flavor. And unless you have a reliable method of removing caffeine from ‘coffee juice,’ it is more practical to get decaf beans directly from producers.

Tim S.

Tim loves roasting, brewing, and experimenting with coffee. After years of perfecting this craft, working as a barista, and owning a small coffee service in college, he has decided to share his knowledge with the world.

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