You’ve brewed a fresh cup, taken that first sip, and—wait, why is it sour? If you've ever found yourself puzzled by this, you're not alone. Sourness in coffee can be a surprise, especially if you’re used to rich, smooth, or even bitter flavors. So, what’s behind that zing of acidity? Let’s break it down.
Coffee Bean Origin: The Role of Geography
Where your coffee comes from plays a huge role in its flavor profile. Coffee beans grown at high altitudes, like those from Ethiopia or Kenya, often have a bright, fruity acidity that some might interpret as sourness. But don’t let that throw you off! These acidic notes are actually prized in the world of specialty coffee, offering a vibrant and complex taste. 
Roast Level: Light vs. Dark Roasts
Have you ever tried a light roast and thought it tasted sour compared to your usual dark roast? That’s because lightly roasted beans retain more of their natural flavors, including their inherent acidity. If you're switching from darker roasts, that acidity can hit differently, often mistaken for sourness. It’s all part of the coffee’s natural character.
Want to explore more about the differences between roast levels? Check out our guide to roast profiles for a deeper dive into how roasting transforms your coffee.
Brewing Method: The Science Behind the Sour
The way you brew your coffee also matters. Sourness can sometimes be a result of under-extraction—when not enough of the good stuff (flavor compounds) is pulled from the coffee grounds. If your water temperature is too low, or your grind size is too coarse, you might end up with a sour cup. On the flip side, brewing too long or at too high a temperature can lead to bitterness. Mastering the balance of water, grind, and time is key to avoiding unwanted sourness.
For a step-by-step guide to perfecting your brewing method, check out our coffee brewing tips.
Appreciating the Complexity
Understanding why your coffee tastes sour can turn frustration into appreciation. That sour note is just one part of the symphony of flavors that specialty coffee offers. Next time you notice it, take a moment to savor it as a mark of quality and craftsmanship.
You can also read:
- "Do we need to rethink the relationship between grind size and coffee extraction?" Perfect Daily Grind, 2022. . Read more.
- “What We Taste When We Taste Acidity” Barista Hustle, 2023. Read more.