Why Does My Coffee Taste Sour?

Wondering why your coffee tastes sour? Our perception of sour taste in coffee has a number of roots. Let's dig into some possible causes of sour coffee and how to prevent them. 

Causes of Sour Coffee

1. Under Extraction

One common cause of sour coffee is under extracting during the brewing process. This happens when not enough flavor is taken out of the coffee grounds while brewing. The longer your coffee brews, the more sugars are extracted from the grounds, making the coffee taste sweeter. But if you go too long, you'll end up with a bitter taste (over extraction).

If you think under extraction is the cause of your sour coffee, here are some ways to avoid it:

How to Avoid Under Extracting Your Coffee

• Pour Over: Try a medium grind size. If your grind size is too course, it can cause under extraction.
• Espresso or AeroPress: Try a fine grind size. Even a medium grind size can cause under extraction with a fast brewing method.
• French Press: You want a more course grind for a French press since the grounds steep in water for a long time. A more common cause of under extraction is steeping the grounds for too short of a time. Let the coffee steep for about four minutes before pushing the plunger down and serving. 

2. Over Roasting 

Over roasting can happen if your coffee is roasted too dark (if you use too many coffee beans, for example), or too fast (i.e. your grind needs to be refined). To avoid over roasting, be sure you have the right coffee-to-water ratio and the optimal size grind for your brewing method.

3. Lower pH

Water plays a major role in brewing, which means you might experience that sour coffee taste if the pH of the water you're using is off (less than 7). Use pH neutral, filtered water to avoid this. 

4. Overheating 

If coffee remains in a heated state post extraction (think heat plates on drip brewers), it might start to taste sour. You'll need to brew a fresh cup of coffee. 

5. Ultra Fresh Beans 

Believe it or not, coffee beans can be too fresh. If you brew too quickly after the beans have been roasted (or "settled"), your coffee will taste sour. Coffee beans need a few days to settle before serving. Some roasters will actually let their beans sit for up to a week!

6. Taste Preferences

The sour coffee taste you're experiencing may just be a matter of taste preference. If you're used to drinking dark roasts, you might associate the fruit notes of a light roast with a sour taste. (Case in point: we once heard someone say their fruity Ethiopian roast tasted like someone poured orange juice into it.) If the sour taste is a matter of taste preference, either stick with dark roasts or slowly work your way from dark to medium roasts and then Colombian/Brazilian to Ethiopian coffees. It's a great way to ease your palate into the full spectrum of coffee tastes.