Help for sour coffee


New member
Dec 28, 2019
I have been having an intermittent problem with sour coffee. According to my research, this is supposed to be due to underextraction. This does not seems to be the problem as far as I can tell. I've made so many changes, one at a time, but nothing solves the problem.

Currently, I use fresh beans directly from the roaster, grind them just before use in a burr grinder (just shy of course), and the beans are stored in an air tight container. I microwave bottled water to 205-210 degrees, then let it brew for 6:30 minutes in a French press. I then pour the coffee immediately into my cup.

Every couple weeks I get a different coffee, so it can't be the beans themselves. I generally start using them 4 days after roasting.

I'm really at a dead end


May 24, 2019
Also you want to try a different brewing method and buy an electric kettle because the microwave might be over heating your water!


Active member
May 11, 2014
Kansas City
I would say you are not using enough coffee... most people use between a 1:11 and 1:16 ratio for french press. 16oz water weighs 473g / 11 = 43g coffee to 473g/16 = 29g. Start in the middle around 35g. You are using around 25g of coffee in 1/3 cup.


New member
Mar 19, 2020
Sour coffee is usually under-extracted coffee. Essentially, the beans didn’t get brewed enough… and so not all the flavors are there to balance out the acids.
We break why this happens and the stages of extraction (the acids come first), if you’re curious.
Here’s how under-extraction tends to happen at home:

· Your beans are ground too coarsely. Fine grounds extract quickly, but large ones take longer because the water needs more time to get into the center of each particle (you know, science). An overly coarse grind size could simply mean each particle isn’t getting the time it needs for a balanced extraction.

· Your brew time was too short. You want to brew long enough to bring out the flavors that will calm down the acids and hit that sweet spot of flavor. With a french press, maybe you plunged the filter down too early. With a pour over cone, maybe you poured your water too fast and it drained too quickly.

· Your water is on the cool side. It’s been proved that the best water for coffee is between 195 and 205 degrees. If it gets below that, it won’t extract the good stuff from the coffee as quickly as it needs to, which can lead to under-extraction.

· You didn’t use enough water. Your coffee to water ratio matters a lot, and if you don’t give each ground the right amount of water it needs to extract a balanced brew, you’ll naturally end up with under-extracted coffee.