During a move I forgot which jar of ground coffee is decaf - usually I refer them by place they had. Is there any test I can perform at home to find out which jar is which type of coffee?

  • There were some test strips on the market but I am not sure if the are still available. You could send the coffee to a lab but the test would be more than the coffee.
    – paparazzo
    Jun 22, 2016 at 11:07

2 Answers 2


Only "Brew a pot and see if it wakes you up in the morning, or not." I can't think of any other test that is practical at home.

Other practical solutions -

  • Mix them and have half-caf until you buy new coffee.

  • Just buy new coffee, as if it was forgotten in the move.

  • And perhaps mark the containers in some way.

    In the overall cost of moving, it's a small expense.

  • "And perhaps mark the containers in some way." now you're telling me ;) I planned to do it but during whole move business I kept forgetting it.
    – Maciej Piechotka
    Jun 22, 2016 at 2:52
  • 1
    I would have thought brew and taste should work if you're familiar with the coffee you keep in.
    – Chris H
    Jun 22, 2016 at 6:59
  • Taste is unreliable if the roast is the same. The effect (or lack of one) over an hour or so is more reliable as an indicator.
    – Ecnerwal
    Jun 22, 2016 at 14:10
  • the Q specifies ground coffee, so many hours have already passed. If you buy nominally the same coffee, decaf or otherwise, ground the same, then yes. But there's much more choice of non-decaf, so if you've chosen your favourite there, you don't have much chance of getting it in decaf. On the rare occasions when I drink decaf I tend to go for a milder flavour and lighter roast so I could tell by eye (plus decaf is has almost always been kept too long in my house)
    – Chris H
    Jun 24, 2016 at 7:12

According to this empirical evidence, only two of the eight people can correctly identify the decaf. Not an academic study, but still shows that you cannot find it by flavor, in my opinion.

Otherwise, you should prepare a cup and go for caffeine test stripes. Still, those stripes will probably cost more than a few jars of coffee.

  • 2
    That is interesting but their analysis was unthoughtful. In one trial, a coin flip would "correctly identify" the decaf 1/2 the time on average, or about 4 of their 8 "tasters." They did 2 trials. If we pretend those 2 were the same (not one hot, one iced), then a coin flip would "correctly identify" 1/4 pairs on average, which is what they saw in their small sample of 8. So those two tasters weren't special. That's what you'd expect from random chance (the default hypothesis or "null hypothesis"). This supports your point "you cannot find it by flavor." See the Triangle Test.
    – Jerry101
    Jul 28, 2016 at 21:48
  • Thanks @Jerry101 for explaining how statistically unsound these results are. You have explained very neatly. I'm sure aware of the triangle test, but I have never heard that somebody tried that for regular coffee and decaf.
    – MTSan
    Jul 29, 2016 at 11:22

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