Experimenting-with-coffee-chemex-bonavita-gooseneck

Coffee Extraction: Sour vs Bitter & how to tell the difference

We recently added a feature to the Angels’ Cup coffee app that lets you record brew methods AND the results. angels-cup-coffee-app-brew-method-extraction-sour-bitter If you’re familiar with brew methods like the Chemex or Aeropress, recording the brew method is straight forward. As you can see in the screenshot to the left, you can record things like temp, grind, brew time, coffee, and water weight. When you have a coffee and water weight entered, the app shows you your brew ratio.

There are a few apps out there that let you record brew data, but if you really want to learn how to make better coffee, you should also keep track of the results. To help you do this, we built a 2-axis chart to record your coffee’s strength and extraction.

Coffee strength is easy to discern. It either tastes too watery or not watery enough. If your coffee is ever too strong, you can solve the problem by adding a little water to it!

Extraction is a little more challenging, and might take some practice to understand. Coffee people usually refer to extraction in terms of sour and bitter.

Sour

If coffee is under extracted it will taste sour because the fruity acidity comes out first. Think about the tart flavor of citrus fruit, or granny smith apples. Those flavors come from acidic compounds found naturally in fruit, and often can be quite pleasant. Candy is often loaded with the same types of acidic compounds, think about Jolly Ranchers or Starbursts. However, for these sour notes to taste good in a cup of coffee, they need to be balanced with the sweetness and even some bitter notes that develop later in the brewing process.

Bitter

If coffee is over extracted, it will taste bitter. Think about the flavor of really dark chocolate, garlic, or medicine. The bitterness in coffee takes longer to develop than sour or sweet notes, but can quickly come to overpower a cup.

Here’s a quick table to help you fix bad coffee:

Flavor  Brew Time Water Temp Grind
Sour  Increase Decrease Finer
Bitter Decrease Hotter Coarser

It’s easy to read about how something tastes, but how easy is it to pick up on in the cup? Understanding extraction, and training yourself to pick up on sour vs bitter, can be a challenge, but a fun one! The best way to really understand coffee is to deliberately brew multiple cups incorrectly, and try them side by side.

Experiment 1: Extraction through brew time

An easy way to mess up extraction is brew time. For this experiment, you will need a “submersion” brewer, one where the coffee grounds are suspended in water with no drainage (i.e. aeropress, french press, clever). A V60 can also work because the filters are thin enough to brew super fast if you want, but a Kalita or Chemex are bad options. You’ll also need good coffee beans with at least medium acidity.

You’re going to make three cups. For one, just follow your normal recipe. For another, cut your recipe time in half, and for another double your recipe. For most people, that will probably mean a 2-minute brew, a 4-minute brew, and an 8-minute brew.

When they’re ready to try them side-by-side, what do you notice? I like to think of it as treble and bass. The under extracted coffee will have all treble and no bass. The over extracted coffee will have the bass dialed up. What if the experiment didn’t work for you? Either a) your beans weren’t very good or were stale, and didn’t have treble or bass to begin with, or b) it just takes time to develop a palate, try again with 1, 4, and 12-minute brew times.

Experiment 2: Extraction through brew temp

This one is tricky, so buckle up. First, you need a variable temp electric kettle or a kettle with a thermometer. If you have that, make three cups of coffee, the first one at 210℉, the second at 195℉, and the third at 180℉. What you’ll probably notice is that temperature affects the sour/treble notes, significantly more than the bitter/bass notes.

Now here’s where it gets tricky. Temperature doesn’t simply increase or decrease extraction, it affects the rate at which specific compounds dissolve, namely acids and carbohydrates. The hotter the water, the more acidity and sweetness you will get, keeping all else equal. However, you will also taste a shift in the nuance of the acidity and sweetness, and this shift will be different for every damn coffee. Brewing a sweet coffee at lower temps seems to produce a beautiful candy-like sweetness. At higher temps we seem to get more of a starchy, bread-like sweetness. This might be acceptable if it’s the only sweetness a coffee offers, or if the coffee needs sweetness to balance some bitterness or sourness.

The basic rule of thumb I’ll offer is this. For sour coffee, decrease temp. Yes that will reduce extraction, but think about cold brew as an extreme example. It’s never too bright. If your coffee is bitter, increase temp. It won’t pull out more bitterness, but it might pull out more acidity and/or sweetness to balance the bitter.

And that’s the basis of ‘dialing in’ a coffee recipe! You start with strength, and then adjust brew time and temp to get the perfect balance of treble and bass for a given coffee. Hope that helps, and addresses some of the comments below. :)

Experiment 3: Extraction through grind size

This is actually the hardest variable to experiment with. On something like a French Press, grind options are limited by what will pass through the filter. For filter brewing, changing the grind size will greatly affect your brew time. The finer you grind, the slower your brew time will be. That being said, one of the best tricks to making great coffee is to figure out exactly how fine a specific method needs to be. Go very fine, see if the coffee comes out bitter, then re-try with coarser coffee and a shorter brew time.

At the end of the day, reading will only get you so far, you have to be willing to experiment. Don’t think of it as a waste of beans. Gulping coffee without paying attention to flavor is a waste, experimentation is the best possible use of good beans. So set aside some time this weekend to have fun with your coffee!

Want to try more coffee?

Angels’ Cup is an online coffee tasting club where subscribers get to blindly sample up to 208 different coffees per year, from over 100 top 3rd wave roasters. Small samples sizes mean you get to sample more coffees for less money. Tasting flights start at only $8.99!

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12 Responses to Coffee Extraction: Sour vs Bitter & how to tell the difference

  1. Cameron December 7, 2017 at 10:00 pm #

    Hey Mr. Borack!

    Thank you for your post; you said something that potentially opened my eyes to my problem: water temperature. Why did you recommend lowering the water temperature if your coffee turns out to be sour? Wouldn’t that increase its acidic taste because of the increased length of time it would take to extract the flavor from the coffee?

    • Jeff Borack June 21, 2019 at 3:22 pm #

      Sorry for the slow response, didn’t even realize the blog was getting visitors. I’ve updated the article to better explain brew temps. Thanks for the feedback!

  2. John December 29, 2017 at 4:51 pm #

    I was reading this article and I’m confused at the advice regarding the temperature of the water. The table suggests that to deal with sour coffee, the water should be decreased, and to deal with bitter coffee the temperature should be increased. Isn’t this the wrong way round? Wouldn’t hotter water extract more and help with sour (underextracted) coffee and cooler water would extract less, dealing with bitter coffee?

    • Jeff Borack June 21, 2019 at 3:22 pm #

      Sorry for the slow response, didn’t even realize the blog was getting visitors. I’ve updated the article to better explain brew temps. Thanks for the feedback!

  3. Jerry Morrison April 11, 2018 at 9:30 pm #

    This is very helpful! But is the “water temp” column reversed? One would expect hotter water to increase extraction and thus increase bitter tastes.

    Also note that the page is unreadable on a mobile screen because the pop-up is squeezed down small without content or a close button.

    • Jeff Borack June 21, 2019 at 3:23 pm #

      Sorry for the slow response, didn’t even realize the blog was getting visitors. I’ve updated the article to better explain brew temps. Thanks for the feedback!

  4. Nils January 16, 2019 at 1:51 pm #

    Hi, in the table it says:
    FLAVOR BREW TIME WATER TEMP GRIND
    Sour Increase Decrease Finer
    Bitter Decrease Hotter Coarser

    Shouldnt it be
    FLAVOR BREW TIME WATER TEMP GRIND
    Sour Increase Hotter Finer
    Bitter Decrease Decrease Coarser
    ?

    That is, if your cup is sour, go hotter?

    • Jeff Borack June 21, 2019 at 3:23 pm #

      Sorry for the slow response, didn’t even realize the blog was getting visitors. I’ve updated the article to better explain brew temps. Thanks for the feedback!

  5. Audrey March 11, 2019 at 9:53 pm #

    Thanks for the helpful article. Did you mean to say this in Article 3 – Extraction through grind size. “The finer your grind, the slower your brew time will be”? Should it be the hoarser your grind?

    • Jeff Borack May 9, 2019 at 7:45 pm #

      Nope, the finer you grind, the slower the brew. The fine particles sort of clog the filter a bit. A coarse grind will brew very quickly. Think about how potting soil drains vs gardening soil.

  6. Efren March 12, 2019 at 8:26 pm #

    Great article. Easy to understand, accessible to the average coffee maker. My coffee from the Aeropress is too weak so I’m going to experiment with longer steep times.

    • Walter June 18, 2019 at 2:54 am #

      if it is weak but balanced in terms of sourness and bitterness, you might want to increase concentration instead.

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