We say time and again that the term “acidity” is used as a descriptor of positive attributes in coffee. Convincing folks that acidityAcidity is a positive flavor attribute in coffee, also referred to as brightness or liveliness. It adds a brilliance to the cup, whereas low acid coffees can seem... ...more is a positive characteristic, and that we’re not talking about the kind of acidity that makes a stomach sourSour is one of four basic sapid (in the mouth) tastes: Sour, Sweet, Salty, Bitter (and possibly a 5th called Umami which indicates savory flavors). In coffee, sourness... ...more, is one of the core dilemmas of the purveyor of fine coffees.
Acidity, the good kind, is responsible for a number of characteristics in coffee, including many of those delicious fruit notes. Knowing a little bit about which specific acidsMany acids contribute to coffee flavor: acetic, malic, citric, quinic, tartaric, phosphoric, etc.: Many acids contribute to coffee flavor; malic, citric, quinic, tartaric, phosphoric, etc. See Acidity or... ...more are responsible for certain flavors can prove to be really helpful in learning how to identify them, and subsequently identifying the coffee you’re going to be the most happy with and enjoy. It also helps in understanding the best way to roast and store a coffee to best promote and/or diminish specific characteristics.
Here’s a quick little primer of a few of the acids found in coffee, and what flavors they lead to.
- Citric AcidCitric acid is, in moderate amounts, a component of good, bright coffees. It is a positive flavor acid in coffee that often leads to the perception of citrus... ...more – Found in high grownHigh Grown, or HG, is a coffee designation that can mean different things in different countries. : High Grown, or HG, is the highest quality Mexican coffee designation... ...more arabicaArabica refers to Coffea Arabica, the taxonomic species name of the genus responsible for around 75% of the worlds commercial coffee crop.: Arabica refers to Coffea Arabica, the... ...more coffees, these acids lead to citrus flavors like orangeOrange aromatics and flavors are prized in coffee, whether they take the form of sweet orange flesh and pulp, or orange peel. Orange flavors or aromatics can range... ...more and lemonLemon notes, as well as other related citrusy flavors or acidities, are prized in coffee. These usually express themselves as a bright accent in the cup, or aromatic... ...more, and sometimes grapefruit, in coffee. This article previously stated that some research shows that citric acid is responsible for most of the acid flavors in coffee, but a 2023 study debunks the belief that acidity is directly related to higher or actual concentrations of citric acid. (Thanks to a follower who shared this!)
- Malic AcidAn acid that adds to favorable perceptions of cup quality; malic acid often adds apple-like acidity, and perhaps other taste aspects recalling apples. Malic acid is yet another... ...more – An organicGrown without the use of artificial fertilizers, herbicides, etc.: Organic coffee has been grown according to organic farming techniques, typically without the use of artificial fertilizers. Some farms... ...more acid that can provide more of an appleApple-like flavors in coffee can take on many different forms. The more common ones we use relate to malic acid brightness, which can recall different apple types: green... ...more or pear-like flavors to coffee. It lets off sweet and crispUsually used as a modifying flavor term, such as "crisp acidity" : Crisp can have several meanings, since it modifies other flavor terms. Crisp acidity might mean bracing,... ...more notes, but can also have stone fruit properties. Check out our tasting article about this acid!
- Phosporic Acid – An inorganic acid, but can really push sweetnessSweetness is an important positive quality in fine coffees, and is one of five basic tastes: Sour, Sweet, Salty, Bitter, Savory (Umami). In coffee, sweetness is a highly... ...more in a coffee when combined with other acids. Produces a sparkling sensation. Tropical fruit flavors like grapefruit or mango are generally attributed to phosporic acid.
- Acetic AcidAcetic acid can lead to vinegar-like flavors in over-mature coffees, or bitterness in high quantities. But in moderate amounts it adds a positive winey note to the cup.... ...more – This is the main component of vinegarA defective flavor taint in coffee, resulting perhaps from poor processing, fermentation, sanitation.: Vinegar-like qualities are a defective flavor taint in coffee, resulting perhaps from poor processing, fermentation,... ...more, so it can present as an off flavor at higher levels. At lower levels, acetic acid can present a clean and pleasant sharpness or lime-like flavors.
- Tartaric Acid – Tartaric acids are common in grapes and can lead to some wineyA taste term to describe a wine-like flavor with a similar perceived acidity and fruit, and some level of acetic acid. It is found most commonly in East... ...more notes in coffee, but can also be sour in higher levels.
- Quinic AcidAn important acid in the chemistry of coffee, positive to cup quality in moderate amounts, but leading to perceived sourness and astringency.: Quinic acid is another double-edged proposition... ...more – These are the bad guys responsible for sour stomachs. Quinic acids increase in production the more the coffee degrades. Dark roasted coffees and older, stale coffees possess high levels of this, while low in other flavor-contributing acids. They present in coffee that was roasted a good while ago or were brewed a long time ago (especially if left on a hot plate).
- Chlorogenic AcidChlorogenic acids (CGAs) are important to coffee flavor, contributing to flavor when in the proper balance and level. They are a group of phenolic acids esterified to quinic... ...more – A natural antioxidant, this acid is responsible for a good deal of perceived acidity in the cup, including aromaAroma refers to sensations perceived by the olfactory bulb and conveyed to the brain; whether through the nose or "retro-nasally": The aromatics of a coffee greatly influence its... ...more. For a long time, it was said that roast level was responsible for the breaking down of some of these acids, but more accurately it is exposure time to the heat during the roast. Prolonged exposure time can result in a reduced perception of acidity even if the final roast level is fairly light.
