Sour coffee
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You’re looking forward to a tasty cup of coffee, but then... yuck! It tastes sour. Not fresh or fruity, but really unpleasantly sour. Sound familiar? Don’t worry, sour coffee is a common problem and luckily easy to fix.

The cause often lies in the grind, water temperature or the roast of your beans. We’ll explain exactly why your coffee tastes sour AND what you can do about it. That way you’ll soon be brewing a cup you can really enjoy again.

Why does my coffee taste sour?

Sour coffee can be a real disappointment, especially when you fancied a full, warm flavour. But what actually causes that sour taste? It all starts with balance: a good cup of coffee has a mix of bitter, sweet and sour. If that balance is disturbed? Then one sour note can take over.

Here are the most common causes:

  • Grind too coarse
    If your coffee is ground too coarsely, the water flows through too quickly. As a result the acids are released first, but the sweet and bitter notes don’t get a chance.

  • Water temperature too low
    Cold(er) water mainly brings out the acids. For most brewing methods, a temperature of 92–96°C is ideal. Cooler than that? Big chance of a sour cup.

  • Light roast
    Lightly roasted coffee beans (often with ‘third wave’ coffee) naturally have more fruity, sour notes. Not everyone is a fan of that, certainly not without the right brewing method.

  • Extraction time too short
    If the water flows through too quickly or your coffee brews too briefly, only the start of the flavour profile ends up in your cup, and that’s often sour.

Tip: sour isn’t always wrong. Some coffees actually have a fresh acidity that makes the flavour complex. It only becomes a problem when it gets unbalanced and unpleasant.

How do brewing method and grind affect acidity?

The way you brew coffee AND how finely you grind it have a huge influence on the flavour, and so on those annoying sour notes too.

Grind: coarse or fine makes the difference

Too coarse a grind lets the water flow through too quickly, so only the acids are extracted from the coffee. The result? A thin, sour cup. Choose too fine a grind and the water flows too slowly, which can give a bitter flavour. It’s all about balance.

Rules of thumb

  • Espresso: fine grind
  • Filter coffee: medium grind
  • French press: coarse grind

Adjust your grind to your brewing method, and you’re already well on your way.

Brewing methods and their effect on sour coffee

One brewing method isn’t the same as another. Every way of brewing coffee draws out different flavours, and therefore more or less acidity. In the table below you can see how different brewing methods handle sour notes, how sensitive they are to it, and what you can do to bring the flavour into balance.

Brewing method Characteristics Sensitive to acidity? Advice
Espresso High pressure, short extraction time, fine grind Yes, very sensitive Use fresh beans, precise grind and timing
Filter coffee Brew time of about 3-4 min, medium grind Moderately sensitive Get the right ratio and grind
French press Long brew time (4 min), coarse grind Yes, with too short brew time Use coarse grind and let it brew long enough
Moka pot Indirect pressure, medium-fine grind Moderate Don’t tamp, don’t use too high a flame
Cold brew Cold water, very long brew time (12–24 hours) Not very sensitive Use a light roast, coarsely ground coffee

Note: always use fresh water of good quality AND the right temperature (92–96 °C) for the best result.

What does the roast of your coffee bean say about the flavour?

The roast of a coffee bean has a huge influence on the flavour. It determines not just how bitter or sweet the coffee is, but also how sour it can taste. Especially with sour coffee, the roast often plays a bigger role than you’d think.

Light roast: fruity, sour and fresh

Lightly roasted beans (also called “light roast”) have a shorter roasting time and so keep more of their original acidity and fruity aromas. This can give a lively and fresh cup of coffee, but if your grind or brewing method isn’t right, that freshness quickly turns into unpleasant sourness.

Medium roast: the balance seeker

With a medium roast (the most common for filter coffee) the acids are already rounded out. You get a lovely balance between sweet, sour and a little bitter. Ideal for those who love an accessible and aromatic flavour without pronounced sourness.

Dark roast: full, bitter and little acidity

Dark roasted beans (“dark roast”) have a long roasting time. As a result, almost all acidity disappears, and a dark, intense flavour develops with chocolate and nutty notes. Perfect if you absolutely want to avoid sourness.

Tip: don’t know what you like? Start with a medium roast and taste from there.

How do you avoid sour coffee?

Avoiding sour coffee starts with paying attention to the basics: your beans, your grind, your water and your timing. Here are the best tips to banish that unpleasant sourness from your cup:

  • Adjust your grind

Using too coarse a grind? Then the water flows through your coffee too quickly and you mostly get acids in your cup. Experiment with grinding a bit finer until you get a rounded, balanced flavour.

  • Get the right water temperature

Brewing coffee with water that’s too cold (below 90 °C) means acids take centre stage. Use water at 92 to 96 °C, just off the boil, for better extraction.

  • Check your extraction time

Is your espresso done within 15 seconds? Or is your filter coffee done in 1 minute? Then the extraction time is too short. Ideally an espresso takes around 25–30 seconds and filter coffee 3–4 minutes.

  • Choose the right coffee beans

Lightly roasted beans are naturally more acidic. Want to avoid that? Then go for a medium to dark roasted bean. Blends are also often softer in flavour than single origins.

  • Use fresh water AND fresh coffee

Coffee beans that are old can lose their acidic flavours or develop nasty sour notes. Make sure your coffee is well stored and always use fresh, cold water from the tap or filter.

Café du Jour tip: coffee beans with a softer flavour

Want to be done with sour coffee for good and looking for a softer, rounder flavour? At Café du Jour we have a number of lovely coffee beans known for their mild character, low acidity and full body. Ideal if you love an accessible cup, without sharp edges.

Recommendations from our range:

Café du Jour 100% Arabica South America

Café du Jour 100% Arabica South America

A silky-soft coffee with only Arabica beans from South America. Subtle notes of caramel and nuts, low in bitterness and perfect for every day.

Piazza D'Oro Dolce

Piazza D'Oro Dolce

A refined blend with a soft body and a sweet finish. Perfect for lovers of a mild, accessible coffee.

Lavazza Qualità Oro

Lavazza Qualità Oro

An elegant and floral coffee with a medium roast. Combines fruity sweetness with a soft body — ideal for those who love finesse in the cup.

Frequently asked questions about sour coffee
Why does my coffee taste sour?
This is usually because your coffee is ground too coarsely, the water is too cold or the extraction time is too short. Lightly roasted beans can also naturally produce a sour taste.
How do you prevent sour coffee?
Adjust your grind size, use water between 92 and 96 °C, extend the extraction time, and opt for medium or dark roasted beans. This will bring more balance to the flavour.
Is sour coffee always badly brewed?
Not necessarily. Some coffees deliberately have a bright acidity, especially specialty coffees with a light roast. It only becomes unpleasant if the acidity dominates and pushes away other flavours.
Are acidic coffee beans of poor quality?
No, definitely not. Acidity can actually be a sign of good beans with complex flavours. But... the way you brew them determines whether that acidity is pleasantly fresh or unpleasantly sharp.