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How can you tell if coffee is really decaf?


Has Daylight Saving Time messed with your bedtime? Or perhaps the tumbling stock market has you tossing and turning past lights-out. Or maybe, just maybe, you can't sleep because of that "decaf" you ordered at dinner.

A long-standing debate among the caffeine-wary is whether decaf served in restaurants is actually what it's billed to be—or is really a cup of the high-octane stuff? Are you among the wide-eyed skeptics? Read on.

Do-it-yourself caffeine detectors called D+caf Test Strips will tell you if your beverage is—or isn't—the real thing. Just stick one of the tiny strips into a spoonful of coffee or tea (sans any milk or sugar, which eliminates drinks like lattes and sodas) and you'll have your answer in less than a minute, according to Discover Testing, which makes the strips. If the line above "D" (decaf) on the strip is darker, you're good to go; if it's darker above the "C" (caffeine), beware—your drink probably contains more caf than you'd like.

All decaf tea and coffee contain a sprinkling of caffeine (less than a milligram per ounce), but these strips purport to alert drinkers if there are more than 20 mg in a six-ounce serving. For some perspective, a Starbucks "tall"  (12-ounce) decaf coffee contains about 20 milligrams of caffeine; its full-caf equivalent contains closer to 260 mg, according to the coffee purveyor's Web site. Discover Testing says that as many as a third of supposed decafs are phonies.

So how much will it cost you to sip in confidence? A box of 20 test strips will set you back $9.95 or just under 50 cents a cup. 

Image courtesy of zoonabar via Flickr

The views expressed are those of the author and are not necessarily those of Scientific American.

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