Acidity in coffee is the bright, tangy, lively taste you notice on the sides of your tongue, the “sparkle” that tasters compare to citrus, green apple or berries. It comes from natural acids in the coffee bean, such as citric, malic and phosphoric acid, and it is a sign of quality, not a flaw. Acidity is highest in light roasts of high-grown, washed coffees from places like Kenya and Ethiopia, and lowest in dark roasts and low-grown coffees from places like Brazil and Sumatra. Chemically, brewed coffee is only mildly acidic, at a pH of about 4.9 to 5.1, much less acidic than orange juice or soda.
| Factor | More acidic (brighter) | Less acidic (smoother) |
|---|---|---|
| Roast | Light roast | Dark roast |
| Altitude | High-grown (above about 1,500 m) | Low-grown |
| Origin | Kenya, Ethiopia, Colombia, Costa Rica | Brazil, Sumatra, lower-grown coffees |
| Species | Arabica | Robusta |
| Processing | Washed | Natural (dry) and wet-hulled |
| Brewing | Pour-over, slightly cooler or shorter brews | Cold brew, French press, adding milk |
| Freshness | Freshly roasted (2 to 4 weeks) | Old, stale coffee (tastes flat) |
Coffee pH is about 4.9 to 5.1. For comparison: orange juice about 3.3 to 4.2, cola about 2.5, beer about 4 to 4.5, milk about 6.7.
What Is Acidity in Coffee?
When coffee tasters talk about acidity, they mean a flavor, not the pH number. Good acidity tastes bright, juicy and clean, and it keeps a coffee from tasting flat or dull, the way a squeeze of lemon lifts a dish. It is one of the main things scored when coffee is cupped; see coffee cupping. Bad acidity is different: a sharp, sour taste usually means the coffee was under-roasted or under-extracted, not that it is “too acidic.”
The Acids in Coffee and How They Taste
| Acid | Tastes like | Notes |
|---|---|---|
| Citric | Lemon, orange, grapefruit | Common in high-grown Arabica; fades as the roast gets darker |
| Malic | Green apple, pear, stone fruit | Crisp acidity in many Central American and East African coffees |
| Phosphoric | Sparkling, cola-like | Often linked to the vivid acidity of Kenyan coffee |
| Tartaric | Grape, wine | Small amounts; adds winey notes |
| Acetic | Vinegar-like when strong; winey in small amounts | Produced in fermentation and roasting |
| Lactic | Creamy, yogurt-like | Higher in some natural and anaerobic coffees |
| Chlorogenic acids | Astringent, slightly bitter | The main acids in green coffee; break down as roasting continues |
| Quinic | Sour, dry, harsh | Forms from chlorogenic acids in dark roasts and in coffee left on a hot plate |
Green coffee is rich in chlorogenic acids, about 4 to 8% of an Arabica bean and more in Robusta; see the anatomy of a coffee bean. Roasting breaks these down and creates other acids, so the balance changes with every degree of roast.
Why Are Some Coffees More Acidic?
- Altitude and climate: coffee grown high up, in cooler conditions, ripens slowly and develops more acids and sugars. That is why high-grown coffees from Kenya, Ethiopia, Colombia and Costa Rica are known for their brightness.
- Species and variety: Arabica tastes brighter and more acidic than Robusta, which is heavier and more bitter. Varieties also differ; SL28 and SL34 from Kenya are famous for their acidity.
- Processing: washed coffees taste cleaner and brighter; natural and wet-hulled coffees taste fruitier or earthier, with softer acidity. See coffee processing methods.
- Roast level: light roasts keep the most bright acids; dark roasts lose them and taste smoky and bitter instead. See coffee roast levels.
- Freshness: acidity fades as coffee goes stale, so buy beans roasted within the last 2 to 4 weeks and store them well; see how to store coffee beans.
How Roasting Changes Acidity
- Light roasts (beans reaching roughly 385 to 410°F) keep most of the citric and malic acids, for a bright, fruity or floral cup. They suit Ethiopian and Kenyan coffees.
- Medium roasts (roughly 410 to 435°F) balance acidity with caramel sweetness and more body, a good fit for Colombian and Central American coffees.
- Dark roasts (roughly 435°F and above) break down most of the bright acids. The cup tastes smoky, bittersweet and heavy, with little perceived acidity, which is why many people with sensitive stomachs prefer them.
How to Brew for More or Less Acidity
- Sour, sharp coffee is usually under-extracted: grind finer, use hotter water or brew a little longer. Bitter coffee is usually over-extracted: do the opposite. See why coffee tastes bitter or sour.
- Water temperature: brew at about 195 to 205°F (90 to 96°C). Water that is too cool leaves coffee sour and thin.
- Method: pour-over with a paper filter shows off acidity most clearly; see our pour-over guide. French press and other immersion brews taste rounder and heavier.
- Cold brew tastes smoother and less tart, which is why it is often called low-acid. But a 2018 study in Scientific Reports found its pH was about the same as hot coffee, so the difference is mostly in taste. See how to make cold brew.
- Milk softens perceived acidity, and a tiny pinch of salt can tame harshness; see adding salt to coffee.
- Water: very soft or very hard water can make coffee taste sour or flat; see coffee and water.
Where Do the Most Acidic Coffees Come From?
- Kenya: famous for intense, juicy acidity, often blackcurrant and grapefruit, from high-grown SL28 and SL34 coffees. See Kenyan coffee.
- Ethiopia: washed Yirgacheffe and Sidamo coffees are bright, floral and lemony; naturals are fruitier. See Ethiopian coffee.
- Colombia: balanced, often red-fruit or citrus acidity with caramel sweetness. See Colombian coffee.
- Costa Rica and Central America: clean, crisp acidity, especially from high regions such as Tarrazú. See Costa Rican coffee.
- Hawaii: Kona coffee, grown on the slopes of Hualālai and Mauna Loa at about 500 to 3,200 feet, has a milder, smooth acidity.
Low-Acid Coffee: What to Choose
If bright coffee is not your style, or acidic drinks bother your stomach, choose a dark roast from a lower-grown origin such as Brazil or Sumatra, whose wet-hulled coffees are earthy and heavy, try cold brew, and add milk. Be aware that coffee can trigger heartburn for reasons other than acidity, including caffeine, so if coffee regularly upsets your stomach, decaf may help more than a lower-acid bean, and it is worth asking your doctor.
Former roastery owner and coffee tour operator. Steve spent five years roasting coffee for his own shop and wholesale customers. More about Steve