Whether you're looking for ways to reduce your caffeine intake for health reasons, or simply craving a cup of coffee late in the day, but don't want to be up all night, decaf might be the answer.
But what is decaf coffee? How is it made? And does it really have less caffeine than regular coffee?
What Is Decaf?
Decaffeinated coffee, known as decaf for short, is ordinary coffee that has had most of its caffeine removed from it before the beans are roasted.
According to the U.S. Food and Drug Administration, for a coffee to be marketed as "decaffeinated," it must have had at least 97 percent of its original caffeine removed.
Which, if you think about it, means a couple of things:
One, decaf is not caffeine-free. Decaffeinated coffee can retain up to 3 percent of its original caffeine content.
And two, there can be considerable variation in the caffeine contents of decaffeinated coffees.
How Much Caffeine Does Coffee Have?
It's easy to find an "average" caffeine content for a "cup" of coffee on the internet, with the most common figure being 95 milligrams of caffeine per 8-ounce cup.
Unfortunately, this isn't terribly meaningful, since hardly anyone actually drinks a literal 8 fluid ounces of coffee at a time. For comparison, a grande at Starbucks is 16 ounces, and a tall is 12 ounces.
Also, averages can be highly misleading. For example, in a roomful of people—half of whom are 50 years old and the other half are 10 years old—the average age in the room is 30 years. But of course, not one single person in the room is actually 30 or anywhere close to it.
To get around this problem, we'll just use Starbucks coffee as a yardstick. Everyone drinks it, we're all familiar with the sizes, and the info on its caffeine content is widely available. Packaged or canned supermarket coffees, like Folgers, will contain less caffeine per equivalent serving, and instant coffee even less.
How Is Decaf Made?
There are three main methods for removing caffeine from coffee. The most common is the direct contact method, which is the one Starbucks uses for almost all its decaf. In this method, the raw beans are treated with a solvent called methylene chloride which binds to the caffeine. When the coffee is roasted, both the solvent and the caffeine are burnt away. (The boiling point of methylene chloride is about 100 F and Starbucks roasts its coffee at 375 to 475 F.)
Fun fact: methylene chloride is also used in brewing beer—it helps to release some of the flavor compounds in the hops.
The Swiss water method involves soaking the raw beans in hot water, which extracts the caffeine from the beans. The water containing the caffeine is drained away, and the beans are then roasted. The drawback to this method is that in addition to the caffeine, it removes a great deal of the flavor from the beans as well. Which makes sense, since by soaking the beans in hot water, they're basically brewing a pot of strong coffee, then pouring it away and reusing the beans.
Finally, there's the so-called "natural" method, where the beans are treated with pressurized liquid CO2. Starbucks uses this method for its decaf Sumatra blend.
Caffeine Content of Decaf
The two main types of coffee are espresso and brewed coffee. A standard espresso drink, like a latte or cappuccino, will contain two shots of espresso, each with 75 milligrams of caffeine, for a total of 150 milligrams. This is true for grande and venti drinks at Starbucks. Tall espresso drinks (12 fluid ounces) contain a single shot.
A shot of decaf espresso contains about 10 milligrams of caffeine, so a grande or venti decaf latte will contain 20 milligrams.
Turning to brewed coffee, a grande blonde roast (16 ounces) drip coffee at Starbucks contains 360 milligrams of caffeine, and a Pike's Place blend contains 310. You might be surprised to learn that brewed coffee contains more caffeine per drink than espresso drinks, but it's true.
Note that darker roast coffees have less caffeine, as the roasting process burns some of it off. Conversely, because the decaffeination process also removes flavor, decaf coffees are roasted longer and darker to make up for the lost flavor.
That's why there is no such thing as a decaf blonde roast. But a grande decaf Pike's Place brewed coffee contains 25 milligrams of caffeine. One way of thinking about it is that it contains the equivalent caffeine of about two sips of a regular Pike's Place (assuming a "sip" is about a tablespoon).
Do Caffeinated Drinks Really Dehydrate?
One last fun fact. There's a piece of popular lore that says that drinking caffeinated beverages like coffee somehow results in a net dehydration to your body, but this isn't so. Coffee, both decaf and regular, is every bit as hydrating to your body as water.