Decaffeinated Coffee: Everything You Wanted to Know

Coffee is one of the most popular drinks in the world, with over 1.6 billion cups of coffee consumed daily. And coffee is intricately associated with caffeine, the chemical that wakes you up and keeps you up. It’s a morning ritual for many folks, making the coffee while blurry-eyed, and taking that first sip of morning joe, waiting for the caffeine to kick in.

But for some folks, caffeine isn’t a friend. It makes them jittery, keeps them up at night, or is bad for their health. Thankfully, decaffeinated coffee  allows enjoyment of coffee’s aromas and flavors without most of the caffeine. And though decaffeinated coffee has a bad reputation for being flavorless, decaf has come a long way from the old-school Folgers green canister found on the grocery store shelf.

What Is Caffeine?

First let’s talk about the magical drug of caffeine! Caffeine, known by the chemical name methyltheobromine, is a stimulant drug, and the most popular drug in the world. It takes about 15 to 20 minutes to kick in, and after that it can last anywhere from 8 to 14 hours depending on the person and amount ingested.

Caffeine is naturally present in the coffee plant itself and can also be found in over 60 other plants like the tea plant and the cola plant. Caffeine is produced by the plants as a defense mechanism. The coffee tree’s leaves have toxic amounts of caffeine, repelling slugs and acting as a natural pesticide. It also encourages pollination as honey bees, like humans, are affected by the caffeine found in the nectar of flowers and will return to the plant over and over again because they enjoy the effects.

Caffeine works by binding to adenosine receptors in your brain. Typically, adenosine, a chemical found in human cells, binds to their receptors and slows down brain activity making you feel drowsy. When the caffeine is introduced into your system it attaches to the receptors instead, blocking the adenosine from binding and making your brain stay alert and awake.

What Is Decaffeinated Coffee?

Decaffeinated coffee is exactly what it sounds like, coffee that has most of the caffeine removed from it.

Wait. Most? Is decaffeinated coffee truly decaffeinated?

Though the name “decaffeinated” makes it sounds like all the caffeine has been removed from coffee, the decaffeination process doesn’t always remove all the caffeine from the coffee beans. 

By law, decaffeinated coffee has to have 97.5 percent of the caffeine removed. A typical cup of drip coffee has 95 to 200 mg of caffeine in it. That means the same cup of decaffeinated coffee could have somewhere between 2.4 mg to 5 mg of caffeine by law. In other words, decaffeinated coffee doesn’t always mean no caffeine. It just means it’s greatly reduced caffeine.

That said, some processes are better at removing caffeine than others. And some trademark processes, like the Swiss Water Process, have their own internal caffeine level audit, where the coffee beans need to have 99.9 percent of the caffeine removed before it goes to the roaster.

Is All Decaf Coffee Low Quality?

The process of decaffeinating beans (which always occurs in the early stage, when the coffee beans are green and unroasted) is an imprecise method of stripping out the caffeine. Coffee beans have over 1000 chemical compounds in them, and in the process of removing the caffeine, other flavor compounds inevitably are stripped out or damaged. 

Equally challenging is that decaffeinated coffee beans are difficult to roast. The process of decaffeination changes the bean, making them less saturated in color and moisture. The dull green (almost brown) beans roast faster and more inconsistently.

Thankfully the decaffeination options have improved immensely, with processes that are more selective about removing the caffeine and leaving the flavor compounds undamaged and intact. And commercial and independent roasters have become more savvy in roasting decaffeinated green coffee beans, producing higher quality decaf beans than ever before.

Methods for Decaffeinating Coffee

There are three industrial methods that can remove caffeine from coffee beans: the solvent method, the water processing method, and the supercritical carbon dioxide method.

Coffee decaffeination always occurs in the green coffee bean state, before it’s roasted. Green coffee beans are first soaked or steamed in hot water so they swell in size. This opens the pores of the beans and allows the caffeine molecules to become more mobile.

Solvent Method

The solvent method can be further broken down into direct and indirect methods. The solvent used in the decaffeination process is either methylene chloride or ethyl acetate. Neither are considered a health risk. FDA regulations allow up to ten parts per million of residual methylene chloride in the coffee, but industry practices usually end up closer to one part per million. Ethyl acetate is a naturally occurring chemical in ripening fruit in tiny quantities but can be synthesized or naturally produced in large batches. 

Both are volatile at low temperatures, with methylene chloride evaporating at 104°F and ethyl acetate at 170.6°F. Because coffee is roasted at a minimum of 400°F for at least 15 minutes, and then later brewed at home with water that is above 200°F, it’s pretty unlikely any solvent ends up in your coffee mug.

The direct solvent method has the steamed or soaked green coffee beans washed directly in the solvent for about 10 hours to remove the caffeine. Once the caffeine is removed, the beans are steamed or immersed in hot water again to remove any residual solvent, and then they are roasted and sold. The solvent typically used in this method is ethyl acetate and beans decaffeinated this way are sometimes labeled as “E.A. processing,” “naturally decaffeinated method” (because ethyl acetate is a naturally occurring chemical), “natural sugar method,” or “sugar cane processing” (where sugar cane molasses is fermented to create ethanol, which is then combined with acetic acid to create ethyl acetate).

The indirect solvent method has the green coffee beans soaking in hot water for several hours, which extracts both the caffeine as well as other flavor compounds. The beans are removed and then water itself is treated with a solvent, removing the caffeine. The water is heated to evaporate the solvent and caffeine, then the same beans are added back into the water without the caffeine. The beans then reabsorb most of the flavor compounds back, never having directly touched the solvent. This method uses methylene chloride and is popular in Europe. Beans decaffeinated this way are sometimes labeled “KVW method” which stands for Kaffee Vereduligs Werk, “European method,” “Euro Prep,” or “Methylene Chloride Method.”

About 70 percent of decaffeinated coffee is processed with the solvent method. If a process is not specified or named on the package, it’s probably decaffeinated using the direct or indirect solvent method.

Water Process Method

The water process method is sometimes referred to as the “Swiss Water Process” or the “Mountain Water Process,” or more rarely as the “activated charcoal decaffeination” process. Both the Swiss Water Process (SWP) and the Mountain Water Process (MWP) are trademarked names. The Swiss Water Process was developed in Switzerland, but the processing plant is actually in British Columbia, Canada. The Mountain Water Process plant is in Mexico. But they all use a similar process that does not involve solvents or chemicals of any type.

A first batch of green coffee beans is soaked in hot water to dissolve the caffeine as well as all the flavor compounds of coffee until the water is fully saturated. This initial batch of flavorless beans are discarded. Then the water is passed through an activated charcoal filter. The filter traps the caffeine molecules, leaving water with all the flavor compounds of coffee, but none of the caffeine. This water is referred to as the green coffee extract.

Now a second new batch of green coffee beans is introduced into the green coffee extract. The extract is already saturated with the coffee flavor compounds BUT it doesn’t have any caffeine in it. So, the extract dissolves the caffeine from the second batch of beans but doesn’t remove any of the flavor compounds, because it has already reached the maximum capacity of flavor compounds that the water can hold. The decaffeinated beans are then removed and sent to the roaster, while the green coffee extract is passed through the activated charcoal filter again to remove the caffeine and the process is repeated.

The Swiss Water Process facility is also the only one in the world to be certified organic, so if the decaf coffee is certified organic, it’s most likely been through the Swiss Water Process.

Supercritical Carbon Dioxide

Finally, the supercritical carbon dioxide method, also known as the “CO2” or “Carbon Dioxide Method,” is the most recently invented method of decaffeination and definitely the most mad-scientist sounding name of them all. 

Water-soaked green coffee beans are placed in an extraction vessel. The vessel is sealed and 88°F CO2 is pumped in at a pressure of 1000 pounds per square inch. Considering standard air pressure at sea level is 14.7 psi and a typical car tire is 32 psi, that’s a significantly high amount of pressure. This extreme pressure turns what normally would be CO2 gas into supercritical CO2 liquid that is nearly as dense as water.

The supercritical CO2 acts as a solvent and dissolves the caffeine from the beans. The CO2 is moved to a different chamber and the pressure is released, with the CO2 going back to being a gas and the caffeine being left behind. 

This method also has the advantage of being more selective in removing just the caffeine and not any of the other flavor compounds. The downside is the cost of this method. A plant needs to process over 3000 tons of coffee beans a year to make a profit, which means this process is often only used for large batches of coffee sold at grocery stores or other mass distribution outlets.

Finding the Best Decaf Coffee

In the end, like all coffee, what constitutes the best decaffeinated beans is a totally subjective topic. A great place to start is to find out if your favorite coffee roaster or company also sells decaffeinated beans.

Some folks prefer Swiss Mountain Process beans, because of the numerous certifications, including the least amount of caffeine present and the organic-certified and Kosher-certified facilities. Others are less particular and prefer to find the best tasting bean for the palate, which is often more dependent on the roaster than decaffeination processing. 

I personally avoid beans that look very dark or overly oily, as very dark beans will have roasted out a lot of the already potentially compromised flavor compounds in a decaffeinated bean. Where I live in San Francisco, my favorite local roasters like Andytown, Coffee Manufactory, Ritual, and Sightglass all produce medium-roasted excellent tasting decaf beans and are all available mail order. 

Other independent roasters like Stumptown, Blue Bottle and Counter Culture have national distribution and can be found in upscale grocery stores across the country like Whole Foods. Finally, there are coffee subscription services like Atlas Coffee Club, Trade Coffee Company, and Yes Plz that offer delivery of a variety of coffee beans, and most offer a decaf subscription option.