Unlocking Better Coffee: A Beginner’s Guide to Acidity

For many new to the world of specialty coffee, the term “acidity” might sound intimidating or even undesirable. However, in coffee, acidity is the prized attribute that distinguishes exceptional specialty coffee from their ordinary commercial alternatives. Understanding and manipulating the acids in coffee to achieve a perfect brew cup is a skill that can take your brews to a whole new level adding complexity and unmatchable enjoyment. This guide will help you understand what acidity in coffee is, why it’s essential, and how to identify and appreciate the different types of acids that can be found in your cup.

What is Acidity in Coffee?

Acidity in coffee refers to the bright, tangy, and crisp flavours that make your cup lively and vibrant. It’s not the same as sourness; instead, acidity adds a refreshing quality that can range from sharp and tangy to sweet and fruity. The level and type of acidity in coffee are influenced by various factors, including the coffee bean’s origin, variety, fermentation & processing methods, and roast techniques​.

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Key Acids Found in Coffee

Coffee beans are a complex mix of organic compounds, and acids play a crucial role in defining their flavour profile. The acidity in coffee primarily arises from organic acids, which are either inherent to the green coffee beans or formed during the roasting process. As a roaster, understanding the organic chemistry behind these acids is essential for manipulating and balancing them in the final cup.

Identify the differences

Citric Acid	Found in lemons, oranges, and pineapples, this acid brings a bright, zesty note. Predominantly found in high-altitude grown coffees, citric acid dominates the cup in excessively light roasted coffee. During roasting, citric acid tends to degrade, but it remains relatively stable compared to other acids. The degradation products can contribute positively to the overall flavour complexity of the coffee​
Malic Acid	Present in apples and grapes, it provides a crisp and refreshing tartness. Common in coffee from regions like Ethiopia and Kenya. Malic acid is relatively stable during roasting, similar to citric acid, and contributes to a clean, crisp acidity. The roasting process can slightly alter its concentration, but proper roasting techniques help in preserving its delicate profile​.
Phosphoric Acid	Imparts a sparkling sensation, with flavours like grapefruit and kiwi. Formed during fermentation processes and controlled roast development. Acetic acid increases during roasting due to the degradation of sugars like sucrose. This acid plays a crucial role in the perceived brightness and complexity of the coffee​.
Acetic Acid	Sharp and tangy, similar to vinegar and kombucha. More prominent in coffees grown in volcanic soils. Light to medium roasts can enhance its sweetness. Phosphoric acid is relatively stable during roasting and contributes significantly to the perceived sweetness in the cup​.
Lactic Acid	Creamy and tangy, like yogurt and buttermilk. Prevalent in coffees processed using certain fermentation techniques, such as anaerobic fermentation. Lactic acid is formed by bacterial activity during fermentation and is preserved through careful roasting practices​
Tartaric Acid	Adds a distinctive tartness, similar to grapes and tamarind​. Predominantly found in certain African coffees. Tartaric acid levels can decrease during roasting, but it contributes to a unique tartness that enhances the complexity of the coffee​

Other Perceivable Acids

Other perceivable acids include chlorogenic acids (CGAs) and quinic acid. Chlorogenic acids are significant contributors to the bitterness and body of coffee. They degrade during roasting into quinic and caffeic acids. The degree of degradation depends on the roast level, with darker roasts having higher levels of these degradation products. While CGAs add complexity and body, their breakdown products can impart undesirable bitterness and astringency, particularly in excessively darker roasts​.

Quinic acid is another compound that adds astringency and contributes to the mouthfeel of coffee. It forms during the degradation of chlorogenic acids and is found in higher levels in darker roasts. The presence of quinic acid significantly influences the bitterness and astringency of dark roasted coffees. Proper roasting and brewing parameters can help mitigate the impact of quinic acid, allowing for a more balanced and enjoyable brew.

Solubility and Extraction

During brewing, the solubility of all these acids affects how they are extracted into the cup. Water chemistry, water temperature, brewing time, and grind size all play pivotal roles in determining which acids are extracted and in what quantities, thereby influencing the coffee’s overall acidity and balance.

Also read: How Does Local Bottled Water Affect Your Coffee Experience?

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Acidity’s Role in Flavour

As know you may know by now, all these acids work together to contribute to a coffee’s liveliness, complexity, and balance. They interact with other flavour compounds to enhance overall sweetness, body, and aftertaste. For example, citric acid can add a sharp, clean finish, while lactic acid provides a creamy, smooth mouthfeel. The interplay between different acids and other compounds can create a rich and multifaceted experience.

Synergy of Acids

Citric and malic acids combined can enhance each other, creating a more pronounced and balanced acidity. Conversely, the presence of bitter compounds like quinic acid can mask acidity, affecting the overall perception of the coffee’s flavour​

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Understanding and Enhancing Acidity

Understanding how to manipulate and appreciate coffee acidity involves a bit of both the chemistry behind it and the sensory experience. The perception of acidity can also be influenced by the coffee’s aroma, with certain aromas enhancing the acidic sensation while others might mask it. The complexity of coffee acidity lies in how different acids interact, with some combinations amplifying the overall tartness and brightness of the coffee​​.

Practical Exercises for Identifying Acids

• Start with Single-Origin Coffees: These coffees showcase unique acidic profiles specific to their region. For example, Kenyan coffees are known for their high acidity and fruity notes.
• Engage in Cupping Sessions: This structured tasting method helps you isolate and identify different acids. During cupping, you can compare various coffees side by side and note the differences in acidity.
• Use Comparative Tasting: Compare coffees side by side to discern subtle differences in acidity. Try brewing the same coffee with different methods, like pour-over and French press, to see how the acidity changes.
• Aroma and Acidity Correlations: The perception of acidity in coffee is not only influenced by the presence of acids but also by the coffee’s aroma. Try a simple experiment by brewing a cup of coffee and then sniffing different aromatic compounds (like citrus peels or vanilla pods) before taking a sip. Note how these aromas influence your perception of the coffee’s acidity.

Final Words..

For over a decade, our crew at Specialty Batch Coffee have focused on not just showcasing all those deliciously exciting acids, but also balancing them so that everyone can appreciate the complexity and individuality of each different origin, variety, process. So, next time you take pick up a bag of our coffee, try to identify the type of acid that is behind those bright, tangy notes and enjoy the lively delicious experience they contribute to your day.

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