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Thread: French Press - why does extraction stop once grounds sink to the bottom

  1. #1
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    French Press - why does extraction stop once grounds sink to the bottom

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Currently reading The world atlas of coffee (James Hoffman)

    p77 French Press

    A couple of different things here compared to what you read elsewhere

    - medium grind rather than coarse
    - after 4 mins break the crust so it drops to the bottom, and then wait 5 mins so the finer particles sink to the bottom (then pour without plunging)

    It says:

    "Many people recommend pouring out the entire pot once the brew is done, to prevent grounds continuing to steep and start to overextract. If you follow the instructions above the coffee should not continue to brew or add negative flavours, so this is not necessary"



    Question

    Why do the grounds stop extracting once the crust is broken and the grounds sink to the bottom?

    What is the difference, in relation to extraction, if the grounds are at the top or at the bottom?

  2. #2
    Senior Member LeroyC's Avatar
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    Quote Originally Posted by johntropea View Post
    Currently reading The world atlas of coffee (James Hoffman)

    p77 French Press

    A couple of different things here compared to what you read elsewhere

    - medium grind rather than coarse
    - after 4 mins break the crust so it drops to the bottom, and then wait 5 mins so the finer particles sink to the bottom (then pour without plunging)

    It says:

    "Many people recommend pouring out the entire pot once the brew is done, to prevent grounds continuing to steep and start to overextract. If you follow the instructions above the coffee should not continue to brew or add negative flavours, so this is not necessary"



    Question

    Why do the grounds stop extracting once the crust is broken and the grounds sink to the bottom?

    What is the difference, in relation to extraction, if the grounds are at the top or at the bottom?
    It's not necessarily specific to where the grounds are, however the grounds sinking to the bottom could be an indication that they've reached or are close to reaching maximum extraction. There's only so much of the good stuff that you can get out of ground coffee so extraction will hit a ceiling at a certain point. Depending on the brewing method once you've reached that point you either get nothing more, or just negative flavour attributes.

  3. #3
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    The more contact the grounds have with the water the more they will extract. There is an optimal point of time to let any beans brew which will depend on time, temp and grind coursness - at a certain point in time you begin extracting the flavored you don't want to!

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    I followed the process in this video -https://youtu.be/eDasYv-IsiE

    and first try it gave very good results. So if what you're doing tastes good, keep doing it, or experiment with different ways.

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    Senior Member trentski's Avatar
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    Well he certainly looks authentic

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    This is mentioned again on p66 of the same book, in relation to "cupping":

    "To end the brewing process, the layer of floating grounds on top of the bowl, called the crust, is stirred. This causes almost all of the coffee grounds to fall to the bottom of the bowl where they stop extracting. Any grounds and foam that remain on top can be skimmed off and the coffee is ready to taste [..] coffee tasters use a spoon to get a small sample of coffee...."




    Quote Originally Posted by johntropea View Post
    Why do the grounds stop extracting once the crust is broken and the grounds sink to the bottom?

    What is the difference, in relation to extraction, if the grounds are at the top or at the bottom?

  7. #7
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    Keen to give this brewing process a shot rather than just a normal espresso

  8. #8
    Senior Member level3ninja's Avatar
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    Behmor Brazen - $249 - Free Freight
    Here is the same information in video form, by the man himself. https://youtu.be/st571DYYTR8
    johntropea likes this.



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