The how, the whys and a little of the history
"the decaf drinker is the top-tier coffee drinker, the purest of all coffee drinkers, because they are drinking it just for the taste"
—James Hoffmann
"I've never understood the "Death before Decaf" hate for decaf coffee. People dedicated to drinking coffee without the benefit of caffeine are simply in it for the taste- doesn't that mean they like coffee more than people in it for the caffeine? "
—some Redditor
For some people, coffee can be a troublesome drink, and this is largely down to the amount of
caffeine contained in it. Caffeine is a central nervous system stimulant, used to relieve feelings of drowsiness or to enhance alertness and cognitive processes. Its effects have been well known and popular for many years, and are a major reason why coffee is consumed. But there are downsides to this drug, notably that it can interfere with sleep and sleep patterns, and in high enough concentrations can cause
heart palpitations and increase blood pressure and hence the risk of having a
stroke. It's for the latter reasons that my docs have encouraged me to reduce my coffee intake. With this in mind I have changed my drinking habits, and now normally have a "proper" coffee first thing (a
cappuchino) and the remainder of my drinks are either decaffeinated or a 50/50 blend of my regular beans with decaf.
For normal, healthy adults, four or five cups a day is considered safe, but pregnant women are encouraged to reduce this to two or three. My cardiologist recommends this level of consumption for me, and because I really do enjoy the taste, I drink decaf after my first one or two cups each day.
So how does this magic happen?
There is a common element to all decaffeination methods. Firstly the whole "green" unroasted beans are steamed or treated with boiling water. This opens the pores of the beans to allow the solvent into the bean itself. Really, the solvent is the only variable.
In 1903, a German coffee merchant named Ludwig Roselius accidentally discovered a method to decaffeinate coffee beans while trying to salvage a shipment of coffee beans that had been soaked in seawater during transit. Roselius and his team found that the caffeine had been removed from the beans without significantly affecting their flavor. They patented this process, known as the "Roselius Process," which involved steaming the beans with a brine solution (often seawater) and then using benzene as a solvent to remove the caffeine. Despite the safety concerns associated with benzene, the Roselius Process was commercially successful and led to the production of decaffeinated coffee.
The original process, used to make the popular Kaffe Hag was to dissolve the caffeine out with benzene (which, while it removes caffeine nicely, can do Bad Things to the body) These days, the solvents used tend to be dichloromethane or ethyl acetate (the latter sometimes referred to as the sugar cane process because it sounds less "chemically" and more natural.), water and the amazing-sounding supercritical carbon dioxide. I will briefly outline the last two. In pretty much all cases, the extracted caffeien can be recovered for sale to (for example) soft-drink manufacturers.
The Swiss Water Method
Often described as "chemical-free", it does use a chemical solvent, that being water. Green (unroasted) coffee beans are soaked in hot water to extract caffeine and flavor compounds. The caffeine-rich water, called "flavor-charged water," is then passed through activated charcoal filters to remove caffeine while retaining flavor compounds. The now-decaffeinated beans are soaked in the flavor-charged water to reabsorb the flavor compounds lost during the initial extraction. This method produces decaffeinated coffee with a full flavor profile.
Supercritical Carbon Dioxide
In this method, water-soaked coffee beans are placed in a chamber filled with highly pressurized carbon dioxide (CO2). The CO2 acts as a solvent, selectively extracting caffeine from the beans.The caffeine-rich CO2 is then removed and passed through a charcoal filter to separate the caffeine from the CO2. The CO2 is reused in the process, making it environmentally friendly. This method is considered safe and produces high-quality decaffeinated coffee. It does seem to be geting more popular, partly because if its percieved environmental friendliness. I like it because it's more cool and "scienc-y".
Triglyceride Method
Here, green coffee beans are steamed to open their pores, and then soaked in a solution of water and triglycerides (usually derived from vegetable oils). The triglycerides selectively bond with the caffeine molecules, extracting them from the beans. The caffeine-rich triglyceride solution is then separated and treated to remove the caffeine, leaving behind the flavor compounds.
This method is less common than other solvent-based methods but like all others, is considered safe and effective.
And finally..
When roasting your own coffee, be aware that decaffeinated coffee beans tend to be denser and have a different moisture content compared to regular coffee beans. As a result, they may require slightly different temperature profiles and roast times. I've found success with lower temperatures and extending the roast time by about a minute.
One of my favourite coffees just now is a decaffeinated medium roast, and I encourage you to experiment with and embrace the decaf. You'll sleep better and posibly live longer. "Decaff before Death!", says I.
Manythanks to C-Dawg for tyop-spotting =]
James Hoffman's video on decaf
Wikipedia article
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