How is coffee decaffeinated?

Most people are aware that decaf coffee is quite simply coffee without the caffeine. However, have you ever wondered, how is coffee decaffeinated? If so, you’re in luck!

In this article, Joe Borg, Royal New York Senior Coffee Trader, will walk you through the four most common decaffeination processes that we carry. In house roasting expert Mike Romagnino, also roasted up four offerings from Colombia that were processed in each of these different methods. He roasted 9 lb. batches on our Diedrich IR-5, roast analyses and curves are included below!

What is decaf coffee and how is coffee decaffeinated?

Decaf coffee is the removal of caffeine from coffee beans during a process that may consist of either a solvent or non-solvent-based process.  Here at Royal New York, we’ve seen an uptick in trendy requests of higher quality decaf coffees as consumers are more interested in knowing more about where their coffee is coming from.

In this article we’ll highlight some of the decaf coffees we source and the different methods of decaf processing. We have sample roasted 4 decaf coffees from Colombia. The 4 decafs processes showcased include Mountain Water (Descamex processed in Mexico), Swiss Water® (processed in Vancouver, Canada) Methyl Chloride (processed in Canada), and Ethyl Acetate (processed in Colombia). Decaf processing removes approximately 99.9% of caffeine content, leaving very little caffeine trace.

Descamex Mountain Water Decaf Processing

Mountain Water Process

The first type of decaf processing we’re looking at is Descamex Mountain Water Decaf Processing. For this process, when coffee first arrives at the plant, they send coffee samples to their laboratory for evaluation. They evaluate these samples not only for caffeine content but also levels of other compounds so they can prepare the appropriate processes for that particular coffee. By doing this, when they finish the coffee decaffeination, they ensure that the final product meets the correct specifications. 

After evaluation, they separate the coffee into batches for processing. In this process, a standard batch size is 5,000 kg.  They then send the coffee to the maximizer, where they treat it with steam under pressure to soften and enlarge the beans. This makes the caffeine easier to remove from the beans.  After the beans are ready, the caffeine extraction process can begin. 

During caffeine extraction, they submerge the beans in a caffeine-free solution of coffee solids under precise pressure, flow, and heat levels in a vacuum. This process selectively removes the caffeine through osmosis.  For coffees with a higher caffeine content, multiple applications of this step may be necessary to reach optimal caffeine content.  Then, they filter the caffeine out of the solution using specialized cellulose and activated charcoal filters so they can reuse it. 

Finally, they then move the coffee through 3 different dryers: a drum dryer like you might find in a wet mill, a horizontal fluid bed dryer, and a vertical “waterfall” dryer. They dry the coffee in these dryers until they reach 11% moisture, which takes around 12 hours. After drying the coffee goes to a polisher. The polisher removes the silver skin and dust to prepare it for export.  All told, this decaf coffee processing method generally takes between 48 and 60 hours.

Mountain Water Process Roast Analysis

Colombia Royal Select MWP Decaf, RNY # 52459, uses Descamex mountain water decaf processing. Check out the roast analysis from Mike Romagnino below:

The appearance of this Colombia Royal Select Mountain Water Process Decaf was dark brown and a little rough edged. I charged at 385 degrees Fahrenheit with 50% of heat applied. As I started moving through duration, the color remained the same and stayed consistent until browning, which came on later in the roast. Just under three minutes I increased heat application to 75% and adjusted airflow to 50% at five minutes of duration. Seven minutes into the roast, I began dialing back heat application.

This coffee took on heat well as I moved toward first crack. I reached the development phase at 8:28 into duration at 386 degrees Fahrenheit. First crack was light and subtle. Throughout development, there were aromas of brown sugar. I noticed momentum slowing at a rapid pace and needed a small increase in heat application as I neared the end of the roast. I finished with a development time ratio of 27.2% and with an end temperature of 403 degrees Fahrenheit.

Tasting Notes: Caramel, lemon and milk chocolate

Layered flavors of lemon, caramel, and milk chocolate with a smooth delicate body.

Shop this coffee below!

Shop RNY # 52459 Colombia Royal Select MWP Decaf

Swiss Water® Decaf Processing

For Swiss Water® decaf processing, once coffee arrives at the plant, it goes through 3 stages of cleaning. The first is to remove dust and debris, then a screen to remove any items or beans which are too small or too big. Finally, the coffee goes through a mechanical polisher to remove silver skin from the beans.  At this point, the coffee is rehydrated, enlarging and softening the beans in preparation for caffeine extraction.

It is at this point that the decaf process starts in full. First, the coffee must come into contact with a proprietary green coffee extract. This extract is only of water and the non-fibrous contents of green coffee, which selectively, through diffusion, removes only the caffeine from the coffee being processed. This is because the soluble solids in the beans and the extract are in balance, so only the caffeine migrates out of the coffee—not the flavor components.  They carefully monitor time, temperature and flow to optimize caffeine extraction. Then, they run the extract through a custom carbon medium designed to trap only the caffeine, and, filters the caffeine removed from the coffee out of the extract. They reuse this extract to decaffeinate the next lot of coffee, so it has to be free of caffeine. 

Once caffeine fully saturates this carbon medium, they incinerate it in a furnace. This destroys the caffeine and reactivates the medium so that they can use it again. 

But now, back to the coffee decaffeination process. They move the coffee to an evaporative mechanical dryer after processing where the focus is on minimizing water activity. Here it dries until it reaches 10% to 12% moisture and is ready for re-bagging and shipment to the buyer.  I find it interesting that the entire decaffeination process Swiss Water Decaf takes only around 10-12 hours! The Swiss Water team cups every batch of coffee decaffeinated to evaluate pre- and post-decaffeination likeness, and applies Six Sigma methodology to their process to deliver consistency across batches.

Swiss Water Process® Roast Analysis

Colombia Royal Select SWP Decaf, RNY # 50824, uses Swiss Water decaf processing. Check out the roast analysis from Mike Romagnino below:

This Colombia coffee was processed as a Swiss water decaf. The color was a brownish gray and uniform. I charged at 385 degrees Fahrenheit and came in with 50% heat applied. Close to three minutes of duration, I increased heat to 75%. Color change was consistent as it moved from a light tan to browning. Color change occurred at 5:28 into duration. First crack was barely audible, light, and gentle. I had to move in closer to hear first crack. I reached the development phase of the roast at 9:24 into duration.

As I moved through development, I had to slightly increase my heat application. Rate of rise started to dip too fast and needed to stay on top of it as I did not want to risk stalling out. Aromas of chocolate were present throughout the development phase. I finished with an end temperature of 395 degrees Fahrenheit and achieved over three minutes of development.

Tasting Notes: Brown sugar, lemon and milk chocolate

Full bodied with notes of milk chocolate and lemon with a cohesive, clean finish.

Try out RNY #50824 in the link below!

Shop RNY # 50824 Colombia Royal Select SWP Decaf

Sugar Cane or E.A. Processing

The next type of decaf processing we’ll look into is Sugar Cane or E.A. Processing. In this process, once they first receive green coffee at the plant, they sort it and prepare it for processing. A low pressure steam process for 30 minutes is used to open the pores of the coffee to allow for extraction of the caffeine. After this process, they then place the coffee in a solution of water and Ethyl Acetate (E.A.). The Ethyl Acetate is a naturally occurring compound and solvent, derived through the fermentation of sugar cane. During the E.A. process, the solvent naturally bonds to the acids within the coffee, allowing the caffeine to be extracted.

Once the coffee has soaked for sometime, they drain the tank and add fresh solution so that the process can continue. This can sometimes take up to 8 hours, pending the ability to remove enough caffeine from the batch. After they remove the last of the caffeine, they then remove the coffee from the tank and prepare the coffee for steaming. Steaming helps to remove any underlying traces of E.A. Finally, they dry the coffee and clean/sort to spec for bagging and export.

Sugar Cane E.A. Roast Analysis

Colombia EA Decaf, RNY # 53906, uses Sugar Cane E.A. decaf processing. Check out the roast analysis from Mike Romagnino below:

This offering from Colombia was processed as an EA or sugar cane process. To the eye, the coffee was different shades of brown and had an aroma of jalapeno. Within two minutes of duration, the coffee started to lighten up in color. It went from shades of brown to an olive green, then into a dark yellow. I marked color change at 5:25 into the roast. This coffee needed heat and applied more heat in the middle of the roast than usual. As I neared first crack, the color smoothed out.

I moved into the development phase of the roast a few degrees earlier than anticipated. First crack was audible and had an aroma of molasses. To keep rate of rise from not dropping too quickly, I had to keep 25% heat applied. I dropped this batch into the cooling tray at 12:28 into duration with an end temperature of 399 degrees Fahrenheit and had 3:20 of development time.

Tasting Notes: Milk chocolate and raisin.

Clean and balanced with a fusion of raisin and milk chocolate.

Interested in trying out a Sugar Cane or E.A. Processed decaf? Shop RNY # 53906 Colombia EA Decaf

Methyl Chloride or M.C. Processing

The final decaf processing method we’ll be looking into is Methyl Chloride or M.C. Processing. Methyl Chloride is a chemical solvent used for extracting caffeine from green coffee beans.

During this process, they soak the coffee beans in hot water to extract most of the caffeine. After that, they remove the beans from the water and add the M.C. solvent to bond with the caffeine. Once that reaction occurs, they remove the compound created from the surface of the mixture and return the beans to rehydrate. Finally, they remove the coffee and dry it to the desired spec, sort it and bag for export. This decaf process typically takes 21 to 22 hours to complete.

Methyl Chloride M.C. Roast Analysis

Colombia MC Decaf, RNY # 53296, uses Methyl Chloride decaf processing. Check out the roast analysis from Mike Romagnino below:

This offering from Colombia was processed using methyl chloride. Initial appearance of this coffee was non uniform and had a color of shades of tan and brown. Color change was an off yellow color and occurred just under six minutes into duration, which was staggered and slightly awkward.  Throughout the maillard phase of the roast, I left a higher percentage of heat applied than I normally would as I noticed my rate of rise was a little sluggish. As I approached the development phase, the roast gained momentum fast and had to dial back the heat application.

I reached first crack at 8:41 into duration with a bean temperature of 382 degrees Fahrenheit. There were aromas of dark chocolate, brown sugar, and cinnamon throughout development. I stretched out the development phase of this roast and wanted to achieve three minutes or more of development time. Historically, I always had better success with roasting decaf deeper and trying to stretch out development phase as opposed to a shorter development time. I finished this roast at 12:04 with an end temperature of 400 degrees Fahrenheit and I was able to achieve 3:23 of development time.

Tasting Notes: Almond and dark chocolate

A creamy texture with notes of almond and dark chocolate.

Shop RNY # 53296 Colombia MC Decaf

Now you know… how coffee is decaffeinated!

We hope that you found this article informative and helpful in learning more about the coffee decaffeination process. Now that you know all things decaf coffee, make sure you check out our decaf coffee offerings.

Shop all available decaf coffee