How Decaf Coffee Is Made

How Decaf Coffee Is Made

There is nothing like a warm cup of coffee to ward off all the tiredness and stress that our busy life inflicts us with. Nothing like that little rush you feel after a few sips, and the whole credit goes to the caffeine present in coffee. Caffeine is a stimulant that naturally occurs in coffee; it infuses energy into the body, making us feel more present, awake, and positive. But caffeine is still a drug, an addictive one, and these words are scary.

Lately, coffee's popularity has been slandered for the seemingly harmful effects of caffeine on health and skin. But, on the other hand, in all its caffeinated glory, coffee has also been linked to several other benefits! 

Such debate points have given way for decaffeinated coffee in the industry in which the caffeine content is minimal. But no matter the view, if you enjoy drinking coffee but want to reduce your caffeine intake for personal preferences or health reasons, decaffeinated coffee is a good alternative.

Decaf Coffee

Coffee itself has been around for centuries, but decaf has only existed for the last 100 years. Decaf is short for decaffeinated coffee. It refers to coffee from coffee beans that have had at least 97% of their caffeine removed. Most decaffeinated coffees have between eight and 14

milligrams of caffeine. Thus, if someone drinks five to 10 cups of decaffeinated coffee, the dose of caffeine could easily reach the level present in a cup or two of caffeinated coffee. Under European law, decaffeinated coffee must contain 0.1 percent or less caffeine in roasted coffee beans, and up to 0.3 percent, or less, in soluble/instant coffee. The coffee decaffeination process primarily involves water, organic solvents, or carbon dioxide, and is carried out at the green (raw) coffee stage. Our article today will take us through the decaffeination process. 

The invention of decaffeinated coffee

The German coffee merchant Ludwig Roselius invented the first commercially successful decaffeination process in 1903 and patented it in 1906. He was the head of the Kaffee-Aktien-Gesellschaft (Kaffee HAG), a cafe he founded in 1906 in "Überseestadt" district in Bremen. Roselius accidentally discovered the process in 1903 when a shipment of coffee was swamped by seawater in transit, leaching out the caffeine but not flavour. He worked out an industrial method steaming the beans with various acids before using the solvent benzene to remove the caffeine. The original Roselius method superheats the raw (green) coffee beans in brine (water saturated with salt) then floods them with benzol, an organic solvent. However, the heat negatively impacted the brew flavour, and benzene, a possible carcinogen, prompted the search for new techniques. The Roselius method is, thus, no longer in use.

Although those techniques from decaffeination's earliest days are still in use today, the process is not as straightforward as you'd expect. Chris Stemman, the executive director of the British Coffee Association, says that specialist decaffeination companies based in Europe, Canada, South America, and the United States carry out the process. 

How exactly do you take caffeine out of a coffee bean?

Today, four major processes are used for decaffeination, broadly categorized into two: Solvent-based processes (Direct-Solvent Process and Indirect-Solvent Process) and Non-solvent-based processes (Swiss Water Process and Carbon Dioxide Process).

In the solvent-based process, a chemical solvent such as methylene chloride or ethyl acetate removes the caffeine. Both agents are safe and approved by the U.S. Food and Drug Administration (FDA), and in 1985, stated that the likelihood of any healthy risk from methylene chloride was so low as to be essentially non-existent. Coffee decaffeination usually uses solutions with one part per million even though FDA rules allow up to 10 parts per million of residual methylene.

Direct solvent Process

In the Direct-Solvent Process, coffee beans are directly soaked in solvent, usually ethyl acetate or methylene chloride, removing the caffeine. Ethylene acetate is a natural fruit ether made from acetic acid, the building block of vinegar. First, green coffee beans steamed for about half an hour to release the caffeine, open their pores, making them more responsive to a solvent. They are then rinsed repeatedly for ten hours, typically in either methylene chloride or ethyl acetate, to bind the caffeine away (remove) from the beans. The caffeine-laden solvent is then drained away and the beans are steamed again to remove any residual solvent. Although that is disturbing to some folks, the likelihood of finding any traces of chemicals in a brewed cup of coffee is very low because coffee is roasted at 400+ degrees and brewed at about 200 degrees.

Some hail ethyl acetate to be more "natural" than other chemicals and safer than methylene chloride because it exists in minute quantities in ripening fruits, such as apples and blackberries. Thus, decaf coffee processed using ethylene acetate is often labelled as 'naturally' decaffeinated or ‘The Ethyl Acetate Method’ because the solvent occurs in nature. However, the ethylene acetate used for decaffeinated coffee could be synthetic because it's difficult and expensive to gather enough in nature. Ethyl acetate is produced commercially from ethyl alcohol and acetic acid from natural ingredients or petroleum derivatives.

Indirect solvent process

In the Indirect-Solvent Process, the beans are soaked in hot water (near-boiling) for several hours, which extracts the caffeine and other flavor elements and oils from the beans. Then, the caffeine-laden water is transferred to a separate tank and treated with a solvent; thus, the solvent never touches the beans. The molecules of the chemical solvent selectively bond with the caffeine molecules, and the resulting mixture is then heated to evaporate the solvent and caffeine.

Finally, the flavor-laden water is put back to the tank with the beans, which reabsorb most of the coffee oils and flavor elements. This process is prevalent in Europe, especially Germany, and primarily uses methylene chloride as a solvent. Hence, it's often referred to as 'KWV Method' (short for Kaffee Veredelugs Werk), 'The European Method,’ ‘Euro Prep' or 'Methylene Chloride Method.'

The Swiss Water Process

The Swiss Water Process (SWP method) is a chemical-free coffee decaffeination method pioneered in Switzerland by Jean Maclang in 1934. However, it wasn't until the late 1970s that scientists and engineers at Coffex developed it as a commercially viable decaffeination method. They modified the process to prevent the loss of coffee flavor using an activated carbon filter and then started a chemical decaffeination plant in Switzerland. The Swiss Water Process was later introduced to the market as a commercially viable process until 1988. The decaffeination processing plant, Swiss Water®, is headquartered in Burnaby, British Columbia, Canada. They are the only facility globally certified organic by OCIA and Aurora Certified Organic and certified Kosher by the Kosher Overseers Association.

The Swiss Water Process uses only water to remove 99.9% of the caffeine and entirely depends on diffusion, i.e., Solubility and osmosis principles. The original Swiss Water Process involved soaking green coffee beans in hot water to dissolve the caffeine and other water-soluble compounds found in coffee including flavor. The water then circulated through an activated carbon filter to remove the. The porosity of this filter is sized only to capture larger caffeine molecules while allowing smaller oil and flavor molecules to pass through it. Thus, we end up with beans without caffeine and flavor in one tank and a separate tank with caffeine-free but flavor-charged water, i.e., Green Coffee Extract. The water is concentrated in an evaporator while the beans are slowly half dried and then sprayed back with the flavor-charged water to reabsorb them.

Coffex refined this procedure in the mid-1980s by removing caffeine from the subsequent batches of beans using the flavor-charged caffeine-free water obtained after processing a batch of coffee. The caffeine-free water absorbs the caffeine from the new beans, but the flavor components cannot pass into the already flavor-saturated water. As a result, the original flavor components never leave the bean in the Swiss water process; thus, the decaf beans retain their original rich, full flavor and are 100% chemical-free.

The Carbon Dioxide Method

The most recent yet selective decaffeination process is the Carbon dioxide method discovered and developed by Kurt Zosel. It removes just caffeine and not the other flavor precursors from the coffee. The process was patented in the early 1970s and licensed to Cafe HAG and General Foods.

Carbon dioxide is usually a gas at normal atmospheric pressure and temperature but becomes a dense liquid-like fluid when compressed to a greater than 50 times atmospheric pressure. The solubility of caffeine in dry carbon dioxide is low but triples if water saturates the carbon dioxide. Thus, the process involves soaking beans first in water to bring the moisture to about 50%, then placing them in an extraction vessel made of stainless steel before sealing. As a result, the beans swell, pores open, and caffeine converts into a mobile form that can diffuse out of the bean.

 Liquid carbon dioxide is pumped in at the operating pressure of about 300 atms and heated to about 150°F. It dissolves and removes the caffeine in the beans in the extraction chamber before moving into the scrubber, where water extracts caffeine from the carbon dioxide. The re-circulation continues for 8 to 12 hours until the 0.08% decaf target is reached. The carbon dioxide is then pumped into a strong tank and recycled to the next batch while the beans dry in a separate tank. Although they still contain moisture and a trace of carbon dioxide, the drying process reduces the moisture to its original level and vaporizes the carbon dioxide.

The outcome of the decaffeination process

The decaffeination process removes between 97% and 99.9% of the caffeine from your coffee, depending on the method used. Thus, a typical cup of decaf coffee has about 2 mg of caffeine, while a usual cup of regular coffee has about 95 mg of caffeine. Most decaffeination procedures are repeated for 8 to 12 hours, depending on the initial caffeine content of the green beans. For instance, arabica beans are only about 1% caffeine, which requires a period nearer to 8 hours. But generally, the target caffeine content for the decaffeinated beans is usually 0.08%.

The intensity of flavour and aromas that remain in the decaf coffee also vary based on the method used. Essentially, coffee has more than a thousand components that contribute to the taste. The Swiss Water Process and Carbon dioxide methods, for example, retain most of the compounds initially found in the beans. With such information at your fingertips, it is now possible for you to choose decaf coffee that best suits your preferences!


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Gakii Mugendi