Decoding Acidity in Coffee: What It Means and How Roasting Shapes It

Acidity in coffee is one of the most misunderstood yet essential elements of a great cup. While the word “acidity” might evoke thoughts of sourness or sharpness, in the coffee world, it refers to something much more delightful: the vibrant, crisp, and lively flavours that give coffee its complexity and character.

Coffee is naturally acidic. On the pH scale, coffee has a pH level of about 5 (a lower number indicates higher acidity, with pH 7 being neutral). Other beverages like wine (2.9-4.2), beer (4-4.4) and orange juice (3.9) have higher acidity levels, yet they are not typically recognised for their acidic taste.

Let’s dive into what acidity in coffee means, how it varies, and how roasting can either highlight or soften this important flavour attribute.

What Is Acidity in Coffee?

Acidity in coffee describes the bright, tangy, or crisp taste you experience when sipping a brew. It’s often associated with fruit-forward or citrusy notes, like the zing of a lemon, the sweetness of a ripe berry or a juicy apple. This characteristic is not to be confused with pH levels mentioned above; it’s more about flavour perception.

The level and type of acidity in coffee depend on several factors, including:

Origin: Coffee grown at higher altitudes, such as those from Ethiopia or Kenya, often has more pronounced acidity.
Variety: Certain coffee varieties, like Geisha or SL28, are naturally more acidic.
Processing Method: Washed coffees typically have cleaner, more pronounced acidity, while natural-processed coffees often lean toward sweeter, fruitier profiles.

Types of Acidity in Coffee

The acidity in coffee can be categorised into different types, each contributing a unique flavour profile:

Citric Acidity: Think lemon, orange, or grapefruit.
Malic Acidity: Resembles the crispness of green apples or pears.
Phosphoric Acidity: Found in some high-quality coffees, it offers a sweet, sparkling sensation akin to soda.
Tartaric Acidity: Like the tartness in wine or grapes.

Each type of acidity can evoke a particular sensation, making it a key contributor to coffee’s overall complexity.

How Roasting Shapes Acidity

Roasting plays a pivotal role in defining how acidity is perceived in coffee. As green coffee beans are roasted, their chemical structure changes, altering the balance of acidity, sweetness, and bitterness.

Light Roasts

Highlight acidity, emphasising the crisp, fruity notes in the coffee.
Retain the bean’s origin characteristics, making them ideal for showcasing high-acidity coffees like Ethiopian or Kenyan beans.
A common choice for coffee lovers who enjoy vibrant, tea-like brews.

Medium Roasts

Strike a balance between acidity and sweetness.
Soften sharp acidity while enhancing caramel and chocolatey undertones.
Perfect for those who want complexity without overpowering brightness.

Dark Roasts

Mute acidity significantly, emphasising roasted, nutty, or smoky flavours instead.
Ideal for coffees where acidity isn’t the primary focus, such as Brazilian or Colombian beans used in blends.

Why Acidity Matters in Coffee

Acidity is what gives coffee its “spark.” It’s the element that makes a cup feel fresh, dynamic, and engaging. Without it, coffee might taste flat or overly dull. For instance, a coffee with bright acidity and notes of citrus or berries can feel energising in the morning, while a smoother, less acidic coffee might be more comforting later in the day.

Whether you prefer a zesty light roast or a mellow dark roast, the key is balance. The best coffees don’t overwhelm with acidity but use it to complement other flavours, like sweetness and body.

Final Thoughts

Acidity is one of coffee’s greatest gifts, offering a wide spectrum of flavours that range from bright and fruity to sparkling and sweet. While it may seem intimidating at first, understanding how roasting shapes acidity can deepen your appreciation for the art of coffee.

Whether you love a cup bursting with citrus or prefer a smoother profile, there’s an acidity level out there for everyone, ready to be sculpted into the perfect brew.