How to Test Coffee Freshness With a Zipper Bag

Most coffee connoisseurs agree that if you want to make the best pot of coffee you can possibly make, you should use the freshest beans you can get your hands on. But if you can't roast your own beans, you might be wondering how long ago the beans you just bought were roasted by the store. This handy and inexpensive trick can assist you on testing your coffee bean freshness.


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    Measure 1/2 cup of your coffee beans and pour it into a medium sized zipper bag. Make sure that there is enough room for the beans and for expansion.
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    Push all the air out of the bag. The fastest way to do this is to press down and roll the beans towards the bag opening. Be sure that there are no air pockets. Zip and seal the bag while it's still rolled up.
    • Another way to remove air from a bag is to zip the bag except for the last half inch, gently pinch each end of the half inch unzipped seam, push together slightly to open the seam, and use your lips/mouth to gently suck the air from the bag (it is easy if you use a straw to suck the air out), pinching and zipping the bag closed. You can actually get a good "vacuum" in the bag this way with practice.
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    Unroll the bag and leave it in room temperature spot away from sunlight. The ideal place would be next to your usual coffee containers.
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    Wait overnight and check.
    • If the bag is puffed up, the beans are within 7-10 days of roasting, signaled by the fact that they're still releasing carbon dioxide.
    • If the bag is still flat, the beans have passed their freshness peak.


  • Generally, it's recommended to use beans within 10 to 12 days of opening the bag.[1]

Sources and Citations

  1. "Cook's Illustrated"; Secrets to a Perfect Cup of Coffee; Keith Dresser; Sept/Oct 2009

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