August 22, 2025 Nicolas Di Stefano

How To Fix Sour Espresso

Key Takeaways:

Why is my espresso sour? Sour espresso tastes sharp, tart, or acidic, often with notes reminiscent of lemon or green apple. It’s a clear sign of under-extraction.
Understanding under-extraction: This happens when the grind is too coarse or the brew time is too short, preventing proper contact between water and coffee.
How to fix it: To correct sour espresso, adjust your grind to be finer or increase your brew time to ensure proper extraction of balanced flavours.

We’ve all experienced those bad coffee days when we're excited about our espresso, but it turns out to be bitter, sour or burnt. Espresso should be deliciously rich and smooth and have an intense flavour and aroma.

In order to avoid sour espresso, you must know what causes it. Keep reading to learn what causes a sour tasting espresso so you never have to worry about this issue.

Why is my Espresso Sour?

Espresso flavours that are sour, bitter and burnt are mostly caused by over-extraction and under-extraction. When coffee is over-extracted, it overcooks and releases undesirable qualities, turning your coffee harsh, bitter, and burnt. Under-extraction results in weak and sour espresso flavours because not enough of the pleasant flavours make it into the cup.

Therefore, it is crucial to find the ideal brewing time if you want an espresso shot that tastes nice and smooth. The sour flavour in coffee is also caused by the tannic acid in the coffee beans. Tannic acid accumulates in the bean's outer skin.

Tannic acid must be extracted at greater temperatures and pressures since it is located in a harder section of the bean. The longer the extraction time, the more likely that bitter tannic acid will pour into your cup. When tannic acid leaks through, the crema will have a visible lighter brown colour rather than a rich thick crema.

How to Tell if Your Espresso is Sour or Bitter

Getting your espresso just right means understanding its flavour. Sour espresso will taste sharp, tart, like lemon or green apple, with a short, flat aftertaste. In contrast, bitter espresso has a harsh, astringent, or like over-steeped tea, with a dry, lingering sensation.

Characteristic	Sour Espresso	Bitter Espresso
Taste	Sharp, tart, acidic.	Harsh, astringent, lingering bitterness.
Aftertaste	Quick, tingling, and lacks depth.	Dry and lingers on tongue.
Crema	Lighter and fragile.	Denser and more rugged.

What Causes Bitter Espresso?

Wrong grind: You need a fine grind when producing espresso. A coarser grind will result in coffee that tastes bland and lacks richness. Your coffee grind should be slightly finer than salt.
Poor quality: Low-quality coffee beans will produce a bitter espresso flavour.
Wrong ratio: Espresso that is made with little coffee will be diluted and watery. On the other hand, if you use too much coffee, the espresso will taste burnt and bitter.
Brewing for too long: An espresso shot will turn bitter if it is brewed for too long.
Temperature is too hot: Overly hot water can result in a bitter espresso taste. Keep your water at 90°C to 96°C for the ideal coffee flavour.

What Causes Espresso to be Sour?

So, what does sour espresso mean and how can you correct your brewing method? You're likely dealing with under-extraction, which means not enough flavour has been pulled from your coffee grounds during brewing. Here's why this might be happening.

Inadequate tamping will result in uneven extraction and a sour taste.
You might not have enough coffee in the basket.
Your coffee is too coarse.
Bad quality of coffee beans or stale beans

How To Fix Sour Espresso

You need high-quality beans and the right grind size to brew smooth espresso with delectable flavours and aromas. Make sure your machine is clean as this is also a very important factor when making coffee.

Are you trying to find the best coffee beans to prevent sour espresso? Try our Primo Espresso Tazza D'Oro medium roast coffee beans, which translates to "the golden cup".

These Arabica coffee beans will produce a flavourful experience that begins with the aroma of sweet peaches and progresses toward subdued overtones of Brazil nuts.
Solve your sour espresso issues with the right coffee beans today!

Additional Reading

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About the Author

Nicolas Di Stefano is a third-generation Master Roaster and Director of Primo Caffe. With decades of family tradition behind him, Nicolas combines time-honoured Italian roasting techniques with a passion for quality, delivering delicious coffee that Australians expect.