One of the big pieces of recent news at Royal is that we’ve elected to cease contracting Methylene Chloride decaf. The reasons are nuanced, but a recent conversation with founder Bob Fulmer made it clear to me that the decision was made at least in part in principle. While the impact of Royal Coffee avoiding Methylene Chloride may not have far-reaching consequences on its global production, our choice is one of millions of small decisions that together we believe will positively impact the health and well-being of our planet and the people, plants, and animals that inhabit it.
In light of this decision, I thought it might be fitting to take a close look at the details of the decaffeination process. While coffee can act as nothing more than a caffeine delivery route for some, there are many of us who drink it for more than its stimulant nature. It’s been suggested that none are more attune to the non-caffeic attributes than the world’s decaf drinkers, as they are free to enjoy the beverage undistracted by its psychoactive properties. This all sounds nice, but there is a problem intrinsic in decaffeinated coffee – the primary obstacle in crafting coffee without caffeine is that the process of removing the drug is detrimental to flavor.
Intro to Caffeine, its Effects, and the Origin of Decaf
Caffeine occurs naturally in more than 60 species of plants, primarily as a defense against insects. It is most commonly found in coffee, tea leaves, kola nuts, and cacao pods (though chocolate professionals are quick to point out the primary stimulant in cacao is theobromine). In coffee, the Robusta species produces roughly twice as much of it as Arabica. The Laurina variety (aka Bourbon Pointu) and the species Eugenioides (one of the probable parents of Arabica) are both naturally low in caffeine concentration; neither are widely commercially available due to their low productivity, both can taste sweet, have a naturally low acidity, and possess pointed, football shaped seeds.
Caffeine was first isolated and named by the German chemist Friedlieb Ferdinand Runge, after receiving a gift of coffee (presumably roasted beans from Yemen) from the prominent statesman-poet Johann Wolfgang von Goethe. Identified as an alkaloid – a class of naturally occurring and generally plant-derived, high pH compounds containing nitrogen – in its pure form caffeine is a bitter, white, water-soluble powder. Like most alkaloids (morphine, nicotine, cocaine, quinine, and strychnine, e.g.) it produces profound psychological effects in humans, but unlike most alkaloids its consumption is almost completely unregulated.
The amount of caffeine that makes it into an average cup of coffee can vary wildly. A recent study showed that a 16 oz cup from a Dunkin Donuts shop had 100 mg less caffeine than the same size cup from a Starbucks café. And the same blend, ordered from the same Starbucks store one day to the next also showed dramatic changes: one cup measured 250 mg of caffeine one morning, another cup yielded over 500 mg the following day. The effect of caffeine also varies significantly from person-to-person, and by method of consumption. I’ve developed a fairly high tolerance and have been known to inadvertently ruin coworker’s sleep pattern by asking them to taste an espresso in the mid-afternoon.
Caffeine’s effects on well-being are generally considered positive, increasing alertness, productivity, and sociability, e.g. However, the substance is moderately habit forming (in part due to your body’s increased dopamine production after ingestion) and over-consumption can result in anxiety, nausea, and in high doses can be lethal. To kill you, it would require you to consume about one cup of coffee for every kilogram of body-weight, a feat about as unlikely as ingesting a gallon of milk.
Decaffeinated coffee makes up about 12% of the current consumer market, but the desire to drink coffee without caffeine is nothing new: the first commercially successful decaf was produced over a century ago, by Ludwig Roselius. His brand, Sanka, produced by his company Kaffee HAG in Germany, appeared on the market first in Europe, then in the United States, sometime between 1906 and 1914. Roselius is credited with inventing the first major means of decaffeinating coffee via chemical solvents. Roselius’ chemical of choice was Benzene, now known to be highly toxic and very flammable, and its use has been discontinued for decaffeination. Today, the two most common chemicals used are Ethyl Acetate and Dichloromethane (aka Methylene Chloride, or DCM).
Chemicals Used for Decaffeination
While it’s easy to feel some concern about solvents like Ethyl Acetate and Methylene Chloride, in truth, the risk to the consumer is quite low. But there are some broader implications, especially for Methylene Chloride, that merit discussion.
Methylene Chloride (CH2Cl2) has been found naturally occurring in volcanic output and in oceans resultant from algae and other normal environmental processes. It’s volatile as a liquid at room temperature, readily evaporating in a matter of hours or days. It is not biodegradable, but as a vapor has a half-life of about five months, degrading in the presence of sunlight and the atmosphere’s abundant hydroxyl radicals.
Update 6/29/2017: Apparently the longevity of Methylene Chloride (aka dichloralmethane) and its escalated concentration in the atmosphere is now being considered a factor in slowing the healing of Earth’s ozone layer. More information from New Scientist here.
It cannot be harvested efficiently, so any industrial applications for the chemical are produced synthetically. Its production also results in the byproducts of two chemicals banned for regular consumer applications: chloroform (a known carcinogen) and carbon tetrachloride (a high potency liver toxin and probable carcinogen).
Methylene Chloride, itself a suspected carcinogen and hazardous waste, has known adverse health effects when inhaled or absorbed through the skin. Short-term (15 minutes) occupational exposure limits in the air are restricted by OSHA to 125 ppm, and the FDA regulates coffee to 10 ppm (though studies have produced results of no more than 1 ppm across numerous samples).
It’s important to restate that Methylene Chloride presents an extremely low risk to the decaf consumer. Even if residual solvent remained in the coffee, it is so volatile that it would either evaporate in storage or off-gas during the roasting process. Any danger related to Methylene Chloride is limited to the environmental impact of its production and the health of those handling the chemical during production and application.
Ethyl Acetate, by contrast, is common in nature and its synthetic replication is low impact, distilled from a heated combination of acetic acid and ethyl alcohol. It’s toxic to insects, and an irritant for humans, but at a much higher threshold than Methylene Chloride, at around 400 ppm, OSHA’s permissible exposure limit. Ethyl Acetate is lethal in very high concentrations at or above 20,000 ppm. Regarded by some as inferior in taste quality to MC decaffeination, its use is less common and was once more expensive. However Royal has recently contracted coffee decaffeinated using this chemical at a comparably priced level to Methylene Chloride.
Methods of Decaffeination
How do these chemicals remove caffeine? There are essentially two methods, known as direct (Roselius’ original process) and indirect. They both operate on the physics principle of diffusion: a substance will move from an area of high concentration to an area of low concentration.
In direct solvent decaffeination, coffee is hydrated (either via steam, immersion, or both) and then repeatedly rinsed with the liquid chemical. The coffee comes into direct contact with the Ethyl Acetate or Methylene Chloride, hence the term “direct.” On each pass, the solvent, now laden with caffeine, is distilled to remove caffeine. The process is repeated until the coffee is ready to be cleansed with water and re-dried.
In the indirect method, coffee is soaked in warmed water. The liquid is then drained, and chemical solvents are added to the liquid solution to remove the caffeine, but they never come into direct contact with the coffee itself. The decaffeinated coffee extract slurry is then reintroduced to the original coffee to re-saturate the beans with flavor. This is repeated until the coffee is sufficiently decaffeinated and ready to be re-dried.
In some cases, the indirect method will preload the warmed water with coffee solids (everything that makes coffee coffee except for caffeine). In this scenario, the water is so saturated with “coffee stuff” that the compounds in the beans being decaffeinated are not absorbed by the water – only caffeine is extracted. When this indirect method is employed, there is no need to re-saturate the coffee, as it will retain all its natural flavor.
Water-processed decaffeination starts out the same way as indirect solvent method using coffee solids, except that after the coffee extract water absorbs the coffee’s caffeine, the caffeinated liquid is simply passed through filters. In Swiss Water’s patented method, the filters are activated charcoal, for example. Note that because the caffeine extraction does not use synthetic solvents, it is less efficient, which has traditionally made it more expensive.
Full disclosure: Royal Coffee, Inc. purchases water process coffee from multiple sources. Our Royal Select decaf has been processed in Veracruz by Descamex’s Mountain Water Process for over a decade, but we’re also regular suppliers of coffees decaffeinated in Vancouver by Swiss Water. Shout out to Swiss Water’s Director of Coffee Mike Strumpf, who was instrumental in clarifying the information I’ve presented above.
There is one other decaffeination method, though traditionally it is viewed as qualitatively inferior and prohibitively expensive. Supercritical carbon dioxide decaffeination works by pressurizing CO2 to levels around 300 times that of normal atmospheric pressure. At this high pressure, the carbon dioxide acts like a liquid solvent, and can be passed through coffee to remove the caffeine, similarly in principle to the direct method.
In every method, there are a few constants:
- The coffee must be pre-hydrated, and then re-dried afterwards.
- Caffeine migrates (sometimes with the aid of solvents) from areas of high concentration (the coffee) to areas of low concentration.
- Less than 100% of the caffeine is removed; the US standard is 97%, meaning that an average 6 ounce cup of decaffeinated coffee may contain around 10 mg of caffeine.
- In most of these methods, the caffeine is recaptured for a secondary profit.
- The quality of the coffee is changed… but using good coffee to start with produces better results.
Royal Coffee and Decaf
Royal’s recent decision to lean more heavily on water process decaffeination comes after a decade of history with the method. In part, our affinity has to do with the fact that it is easy for us to pre-select green coffee in advance, buy it directly, and then have the lot processed for us. This allows us to choose great quality from our network of producers, and ensure that prices paid across the entire supply chain are fair. It also gives us full transparency of quality, and improvements in quality in the world of water process continue.
Additionally, there’s clearly much more enthusiasm from our customers for water process. Through the first nine months of 2016, a little over 75% of Royal’s purchases of decaffeinated coffee bags have been water process, compared to less than 20% Methylene Chloride (the other 5% is Ethyl Acetate). For some roasters water processed coffees are still prohibitively expensive, and we plan to continue offering Ethyl Acetate as a lower cost option. However, the difference in cost between any decaf method, and notably the price of water process, is at an all-time low.
Water process decaffeination has proven that chemical solvents are not necessary to decaffeinate coffee. We’re not abandoning Methylene Chloride because it doesn’t work, or because it’s commercially unviable. It’s simply not something that’s needed to do the job, and we have found reasonable alternatives that better conform with our mission.
So get ready to enjoy more coffee, guilt (and caffeine) free.