What is Acidity in Coffee?
by Beatrice MarkenzonJan 4, 2022
Acidity is a term that’s often used to describe coffee, usually in a positive light. What does acidity refer to in coffee, though? Acidity is used to describe a range of flavors that are perceived in coffee and can be directly attributed to acids found in the coffee beans.
The Roasting Process Changes the Acids in a Coffee
Simply defined, an acid is a substance that has a pH lower than 7, which means it gives off H+ ions in an aqueous solution. When we taste an acid, the H+ ions that it gives off activate neurons on the tongue, which, in turn, send signals to the brain that we associate with different flavors. The specific flavors we identify from an acid depend on its precise chemical makeup.
As green beans undergo chemical reactions in the roasting process, the concentrations of specific acids change. Most acids degrade at higher temperatures, but some increase. Generally speaking, the roasting process tries to bring out the best mixture of naturally occurring acids found in a specific coffee, as these are the compounds that give the coffee its unique characteristics.
Acids Found in Coffee and Their Characteristics
A number of different acids are found in coffee. In this survey, we’ll focus on the ones that survive the roasting process, as they are the acids that affect a coffee’s final flavor. The first ones listed below have a positive impact on a coffee, while those lower on the list can have good and bad effects.
Citric acid is found in arabica beans grown at higher elevations. The same acid that’s found in citrus fruits, this acid is associated with notes of lemon, orange and, when occurring with phosphoric acid, grapefruit.
Phosphoric acid tastes sweeter than most acids. It can turn an otherwise sour-tasting citrus flavor into a sweeter grapefruit- or mango-like one.
Malic acid is sometimes associated with hints of stone fruit, such as peaches or plums, but it’s more common to taste apple or pear in a coffee that has malic acid.
Chlorogenic acids (CGAs) are largely responsible for a coffee’s perceived acidity. Compared to other acids, they degrade rapidly in the roasting, which is why light roasts are described as “bright” and “acidic” more often than dark ones.
Acetic acid, which is the same acid that’s found in vinegar, may produce a pleasant sharpness at lower concentrations. Higher levels of acetic acid, though, are unpleasant. A coffee that has a lot of acetic acid probably wasn’t properly processed.
Tartaric acid, similarly, produces a sour taste at high concentrations. At low levels, however, it can offer up grape-like or winey notes, which isn’t surprising since it’s found in grapes.
Quinic acid is produced as other acids degrade. High concentrations of it are common in darkly roasted coffee, stale coffee, and coffee that was brewed several hours ago but kept warm on a hot plate. Although it gives coffee a clean finish, quinic acid is the main acid that turns stomachs sour.
Many of the tastes you identify in coffee can be directly attributed to the acids contained within them. If you can identify acids you prefer, then you’ll be able to look for coffees that have been grown or roasted in a way likely to produce those acids.
Acidity in Maud's Coffee
Maud's French Roast From the Coast: This coffee roasted to a perfect dark brown bean and has delicious burnt undertones. A wonderful bold cup that's flavorful, shiny with oil and has a diminished acidity.
Maud's Kona Coast: This rich, low-acidity coffee is roasted to a perfect dark brown bean and has delicious chocolate-nutty undertones.
IB Medium Roast: Blended with South American beans and perfectly balanced, this coffee is bright enough for morning with a light, clean acidity and rich enough for dinner.
Maud's Mellow Mood Decaf: This cup of coffee is nuanced with a syrupy sweet berry acidity and finishes with a full, chocolaty body.
Maud's Organic Sumatra: Some of the world's finest premium coffees are grown in Sumatra. These coffees are distinguished by their full body, more earthy than Java Arabica, and with a low acidity.
Maud's Organic Colombia: This classic organic Colombian coffee brings together a mellow acidity and strong caramel sweetness, with a nutty undertone.
Maud's Organic Guatemala: This highly rated and well-known gourmet coffee is light-medium roasted, but brews as a full-bodied coffee with medium acidity and unique smoky, chocolaty undertones.
Maud's Double Caffeine: Packing over 200mg of caffeine into just one cup, this dark roast coffee is specially roasted to draw out natural flavors and pronounced acidity.
Roastmaster Reserve Organic Dark Roast: Tasting notes for this exotic blend include medium acidity, cane sugar sweetness, a creamy body with sweet caramel overtones, and a slight cocoa note on the finish.
Roastmaster Reserve Guatemala Dulce Leonarda: This dark roast blend boasts hints of caramel, cocoa and tobacco, it delivers a lemony citrus acidity and a beautiful floral finish.
Roastmaster Reserve Organic Decaf Roast: This decaf is roasted dark to develop notes of chocolate & nutty undertones. The strong caramel sweetness is low in acidity and is an evenly balanced sweet medium-body.