Our Approach to Acidity in Coffee

UNDERSTANDING COFFEE ACIDITY AND ITS ROLE IN YOUR CUP

The first image that forms in most people’s mind when the word ‘Acid’ is brought up are of flavours that are sour, tangy, bitter or astringent and often associate acids with an unpleasant experience. Within coffee though, acidity is viewed very differently - to a brewer it can be seen as a very necessary trait bringing liveliness, sparkle and brightness to a cup. It does the heavy work of separating a flat and dull coffee from one that is vibrant and alive! 

Coffee, regardless of its processing methods, genetic makeup or roasting styles, is inherently acidic. The intensity and quality of the acidity will vary depending on the genetics of the coffee, the way it was processed at origin and the style with which it was roasted or brewed. However, these factors only influence the acidity that is already present. For many people, acidity in coffee can be quite polarising - it is either seen as a very desirable trait in the cup or as a note that can be very off-putting.

Acidity in coffee comes from organic acids that are part of the green coffee seed’s chemical composition, and can be enhanced or destroyed in the roasting and brewing process. Good acidity is often described as bright or lively whereas poor acidity can often taste sour or unpleasant. The most commonly found acids in coffee can be broadly classified as:

• Malic and Citric: found in fruits like red and green apples, pears, berries, lemon and other citrus fruits and are seen as desirable flavours
• Chlorogenic Acids: are the most common type of acid and tend to break down by heat during roasting to create the following acids
• Lactic: contributes a creamy, smooth texture and tactile body similar to dairy-adjacent foods
• Phosphoric: sparkly, effervescent feeling that is very similar to drinking a soda
• Acetic: vinegar-like and often considered unpleasant

 

ACIDITY IN PLAY

When tasting a coffee, you are never just tasting one component of the coffee alone. Often, we taste acidity alongside body, sweetness or bitterness. These components interact with each other as well as with our sensory receptors to create a cohesive experience that defines the final cup.

Acidity and sweetness in a cup make for the most pleasurable tasting experience. When both are in balance, the outcome is a delicious cup that has liveliness accompanied by a sweet aftertaste. High acidity with unbalanced sweetness can either create a sharp and sour taste, or a flat and cloying experience. 

Acidity and body are often indirectly proportional to each other. If the body of a coffee is high, the acidity is usually muted whereas when the acidity is high, the body is often thin and texturally light. A lightly roasted Ethiopian washed coffee often tastes tea-like and light-bodied and is perceived as being bright and lively, while the same coffee roasted for espresso will have a more substantial body and a noticeable drop in acidity. 

Acidity and aftertaste go hand-in-hand. A well structured acidity in a coffee stays on the palate even after finishing the sip and leaves the drinker desiring another sip of that coffee. Flat and muted acidity create for quick and unmemorable aftertastes. They tend to be less interesting and often feel less complex.  

WHAT ROLE DOES ROASTING PLAY IN ACIDITY

The acids in green coffee are broken down during the roasting process. As a roast progresses, Maillard reactions and caramelization break down the complex sugars and proteins in coffee into simpler particles that are easier to extract, adding to the body and perceived sweetness of the cup at the expense of acids. 

Depending on how the Roaster wants to highlight a particular coffee, they may choose to roast it as a light, medium or dark roast, and with varying overall roast durations, to produce their desired result. 

A lightly roasted coffee typically has a lower end temperature (201℃ to 210℃) and a smaller overall roast duration, which limits the breakdown of acids during the roasting period and helps preserve the brightness and complexity of the coffee. The aim here is to preserve and call attention to the coffee’s flavour profile. A darker roast, on the other hand, can have a much higher end temperature (≦220℃) and may have been roasted for a longer duration. Some of the acids that break down at lower temperatures are lost during this process, and therefore, darker roasts are often perceived as having lower or muted acidity. 

This is why typical, Nordic-style roasts that are known for achieving extremely low end temperatures tend to push acidity to the forefront while traditional Italian style roasts focus on body, chocolate notes and roast development. Neither styles are bad, they are just optimized to highlight different aspects of the tasting experience.  

ETHICA’S APPROACH TO ACIDITY AND ROAST STYLE

Here at Ethica, when deciding on our roasting approach to a new coffee, we aim to strike a balance between shining a spotlight on the flavours within the coffee and the method with which we brew it. Balance, a term you will often hear when roasters describe their coffee, is part-sensory and part-stylistic. For us, it often is about achieving clarity and retaining complexity in the cup through a ‘less is more approach.’ 

For our Espresso roasts, we want to be able to extract the flavours easily, without spending too much time and wasting too many shots when dialing-in the coffee. The coffee has to pair well when served with milk and must also taste balanced on its own as an espresso or an americano. The experience of tasting a highly acidic espresso could almost be considered jarring, if it isn’t sufficiently supported by ample viscosity and sweetness created during the sugar-browning reactions of a roast. For those who prioritise sweetness and heavier textures in their coffee, one cannot go wrong with Ethica Espresso, our house espresso made with a single origin Brazilian Natural. The sugars and caramels in this coffee pair deliciously with milk but also taste rich and decadent on their own.

Our Filter roasts, on the other hand, are much lighter roasts that have only begun to flirt with caramelization before we end the roast. Here we are seeking to balance extreme acidity without suppressing it - think of it as a dance between clarity, sweetness and complexity alongside brightness. For those wanting to venture to broader horizons, try the Kenya Kamwangi, a sparkly, juicy washed Kenyan coffee with notes of blood orange and honeyed sweetness. If balance is what you crave, the Ethiopian Chelchele Supernatural is a sure bet, with a softer, more rounded acidity that blends well with its peach and red wine notes.   

Acidity in coffee is an ongoing conservation that is constantly evolving and changing. One thing is for certain - that acidity in coffee is real and that it can influence the sensory perception of a coffee. As we seek to continuously refine our roasting approach, our emphasis will always be to offer coffees that are easy to approach, and are balanced yet retain their complexity and nuance.