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Thread: Espresso Re-extracted - Experimenting with CO2

  1. #1
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    Espresso Re-extracted - Experimenting with CO2

    Over the past year I spent quite a lot of time thinking (and writing) about carbon dioxide and its role in espresso extraction. I wondered if "re-charging" stale coffee with carbon dioxide could make it pour like fresh coffee.

    Yesterday I did a little experiment and the result was so astounding that I repeated it again today, on video.

    The experiment?

    I pulled a shot with some old pre-ground coffee that I was given by a friend. As expected, it was dark and thin - no crema. Without the benefit of flow control, it would have been messy...

    Take two.

    Next, I added a small amount of bi-carb to the spent puck and extracted it again. Hello thick syrupy pour and crema!

    It still smelled stale and nasty, but it poured almost like fresh coffee. Despite being at least several months old.

    Anyway, here's the video:

    https://youtu.be/aFeV8vxHVK4
    Last edited by MrJack; 28th August 2017 at 11:50 PM.
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  2. #2
    Senior Member flynnaus's Avatar
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    Interesting. Unfortunately the smell and taste are more important to coffee enjoyment than appearance of the pour.
    What if you added a small amount of bi-carb to the grounds rather than the spent puck? What if you added a very small amount of bi-carb to freshly ground coffee (ie does it affect the flavour)?

  3. #3
    Senior Member Magic_Matt's Avatar
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    So, did you drink it?
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  4. #4
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    Quote Originally Posted by flynnaus View Post
    Interesting. Unfortunately the smell and taste are more important to coffee enjoyment than appearance of the pour.
    What if you added a small amount of bi-carb to the grounds rather than the spent puck? What if you added a very small amount of bi-carb to freshly ground coffee (ie does it affect the flavour)?
    Absolutely! I am not proposing this as a method for resurrecting stale coffee

    The point was really to see how significant the loss of CO2 from coffee (as it ages and even post grinding) could be on the extraction process.

    Could it (and it alone) be the reason that the grind typically needs to be adjusted? Perhaps!

    Many people seem to think that coffee needs to be completely "de-gassed" post roast. Hopefully this goes some way to debunking that idea.
    Quote Originally Posted by flynnaus View Post
    Interesting. Unfortunately the smell and taste are more important to coffee enjoyment than appearance of the pour.
    What if you added a small amount of bi-carb to the grounds rather than the spent puck? What if you added a very small amount of bi-carb to freshly ground coffee (ie does it affect the flavour)?

  5. #5
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    Quote Originally Posted by Magic_Matt View Post
    So, did you drink it?
    I wouldn't have drunk it even if it wasn't pre-ground I imagine the bicarb may have been an improvement!

    Goes to show a great looking shot and a great tasting shot are not necessarily the same thing
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  6. #6
    Senior Member simonsk8r's Avatar
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    Awesome experiment, love seeing this sort of thing!

  7. #7
    Mal Dimal's Avatar
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    Maybe the next step is to rig up a small pressure vessel and try recharging the coffee using CO2 gas...

    Mal.

  8. #8
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    I have thought about it I have a bottle of CO2 in the garage...
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  9. #9
    Senior Member matth3wh's Avatar
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    Behmor Brazen - $249 - Free Freight
    Just wondering out loud ... would you suspect big corporations take advantage of this stuff and may have in some way used it to enhance the look of their products. 🤠
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