Why does coffee have to sit in a French press for like 5min to be strong enough, whereas with pour over the water is only in contact with the grounds for 10-15 seconds and produces a similar strength?



My first guess is that it has something to do with gravity pulling out the flavor as it narrows through the tunnel of Godly caffeination, my second guess is absolute fucking magic…

Edit: haha makes you pick a flair but I literally cannot think of a subject that doesn’t relate to coffee so we’ll go with “physics.”

In: Physics

Drip coffee still has long contact between grounds and water. The funnel forces the water to slow.

When you use a drip coffee machine each water droplet passes its way through the various layers of coffee grounds, absorbs from each part as it goes, and ends up decently strong. For a French press the grounds mostly float, then descend and circulate slowly through all the water. It’s all about contact with the grounds in the end, and both methods work well.

French is still better

I don’t know why the difference but the result is completely different. Say you take the same temp and quantity water, coffee and grind, you end up with two completely different flavors of coffee. To me French tends to be bolder flavor. But the biggest kicker I’ve learned. You can take drop coffee and make some great iced coffee out of it. If you try to make French press coffee into iced coffee it’s bitter as fuck. French press coffee becomes more bitter the colder it gets.

Ahh as a physics person that loves coffee, this just makes me happy.

This has less to do with physics but rather coffee preparation. If you take a look at any coffee brewing guide they will recommend that you grind coarser for french press, and finer for drip.

Coffee is made when water “washes” off the soluble material from your coffee beans. Larger pieces of coffee (like those that you’d use for french press) have less surface area than finer ground coffee (like drip coffee). So while contact time between French Press and Drip differ vastly, the amout of soluble material that the water extracts for each method is similar due to it’s grind size.

Similarly, that is why you need an insanely fine grind for espresso because all the extraction happens in 30 seconds.

It’s not as much about how long the water is in contact with coffee than how long the coffee is in contact with water.

I can speak to something people are missing, but I have no idea on the strength of impact it makes.

From a chemistry point of view, the amount of solvent you use changes how much you extract from a matrix. In this case, the water is the solvent, and the coffee is the matrix.

Since it’s ELI5, I won’t bother to look up the equation, but the gist is you’ll get a better extraction if you wash the matrix with the least amount of solvent multiple times, rather than one big wash once. If I want to use my solvent economically and most effectively, 3x washes with 15ml will extract more than 1x wash of 45ml.

The same happens with pour over vs steeping. The act of pouring over acts like washing the matrix more than once, thus extracting more from the coffee.

As to the actual amount of difference it makes, I have no idea. It’s probably the grind size that makes the most difference, like spsfisch says. But that’s a factor from the chemistry perspective.