Without acidity, a coffee will tend to taste dull and lifeless. Acidity is a desirable primary coffee flavor sensation that is perceived as a pleasing sharpness toward the front of the mouth, a numbing sensation on the tip of the tongue, or a dryness at the back of the palate and/or under the edges of the tongue; denotes the quality of a coffee.
A good acidity will lean towards being sweet, crisp and tart – enhancing the other qualities in a coffee.
A bad acidity will taste sour and stringent, sometimes almost chemically.
Roast Level Affect on Acidity
As many of the acidic qualities are imparted by the organic compounds (such as chlorogenic acid) found in coffee, lighter roasts will generally have brighter acidity than darker roasts. This is because the organic chemicals are slowly destroyed during the roasting process, with the sugars caramelizing and the sweetness muting the acidity.
Acidity will generally decrease and become less prominent as a roast gets darker – a light or medium roast will have higher acidity than a dark or espresso roast. So is espresso less acidic than regular coffees? Yes. What people generally tend to misinterpret as acidic in espresso beans is the presence of more bitter compounds from the roast level. A good espresso should not be burnt and bitter.
Coffee Acidity is not pH Level
Acidity does not, however, refer to the pH level (degree of acidity) of the coffee, nor should it be confused with the character of sourness (an unpleasant, undesirable sharpness or over-fermented bitterness).
A high acidity is described as bright while a low acid coffee may be described as smooth, but if it is too low it will be considered unexciting and boring. A total lack of acidity may also result in a flat coffee.
Coffee does indeed have a pH level, but is not a useful measure of flavor. It would vary depending on brewing method and roast level, but not significantly. Black coffee generally lands around a pH of 5 (acidic, not basic) and milk has a pH of 6 (slightly more neutral). This means that adding milk to coffee makes it slightly less acidic by way of dilution. [source]
Acidity – One of the Major Coffee Characteristics
Acidity is a basic taste and one of the major coffee taste characteristics along with body, aroma, sweetness, bitterness, and aftertaste. These qualities are used by cuppers (professional coffee tasters) to judge coffees and compare the qualities of different coffees.
The desirable quality of acidity is due to acids in the coffee combining with sugars and increasing the coffee’s overall sweetness while also adding a certain vigor to the coffee.
The Taste Qualities Imparted by Bitterness
A coffee’s acidity may impart a pleasant tartness, or snap, somewhat like a dry wine, yet it should not be so acidic that it causes bitterness.
Acidity is often described as dry, sharp (e.g., a sharp radiance enhancing the flavor), vibrant, lively, moderate, or dull. A coffee’s acidity may have a subtle fruity quality which may be further specified as, for example, citrusy, lemony, or berry-like.
Top 3 Best Coffees for Acidity
High-altitude premium coffees known for their bright and vibrant acidity include:
Mexican coffees tend to have a bright, clear acidity, in contrast to the overwhelming acidity typically present in Yemen Mocha coffees, which may even taste distinctively winey and sweet with a winey aftertaste.
Best Low Acid Coffees
If you’re looking for a coffee with low acidity, you’ll find your coffee tends to be easier drinking and smoother. Your best bets here are:
The tradeoff here is that the coffee will have less of a “kick”. Coffees with low acidity are generally looked down upon, but since coffee is a personal experience, only your own opinion should matter.
Coffee and Espresso Brewing Tips
If you want to experience the fine flavors and aromas of your gourmet coffee beans then see our section on Coffee Brewing. You can also read comprehensive coffee taste profiles of the best Gourmet Coffees and then see the detailed instructions on preparing truly amazing Espresso Drink Recipes.