How The Roast Levels Affect The Acidity Of Brewed Coffee

dark roast coffee and open book

It’s no secret that coffee can be a highly acidic drink. And, while the tangy notes of more acidic coffees might suit some coffee drinkers just fine, others prefer their coffee a little more on the mellow side. But what affects the acidity of coffee, anyway? And how can you choose the coffee best suited to your taste?

As a rule of thumb, the darker the roast, the less acidic your coffee will be. Light roasts typically have the highest acid content, while dark roasts have the lowest. 

But roast levels don’t only affect acidity. Choosing your ideal roast is all about finding the perfect balance between acidity and flavor. To do this, it helps to understand the differences between coffee roasts and the unique flavor profile each has to offer. 

How Does Roasting Affect the Acidity of Coffee? 

There is more to coffee than acidic or non-acidic. Coffee beans contain many different types of acids, all of which contribute to the overall flavor. These acids are broken down into two groups: organic acids and chlorogenic acids. 

Organic acids give coffee its pleasant flavors. Think fruity, juicy, smooth, and tart. Chlorogenic acids, on the other hand, are what give some coffees that bitter, sour taste that roasters try to avoid. 

Roasting is the process of drawing out the desired acids while suppressing the less desirable ones. The more heat applied during roasting, the more organic acids are drawn out of the beans, resulting in a flatter, mellower flavor. However, unless you’re careful, the longer coffee beans stay in the roaster, the more the dreaded chlorogenic acids can concentrate, making the beans bitter and unpleasant. 

I’m not suggesting that dark roasts are worse-tasting than light roasts. I can’t overstate that no one roast is objectively better than the other. In the hands of experienced roasters, even the darkest roasts will have a smooth, pleasant taste. But it’s important to know exactly what impact different roast levels have on your beans. To do this, let’s take a closer look at what each roast level has to offer.

What are the Different Coffee Roast Levels?

For people getting into coffee for the first time, choosing a roast level can be overwhelming. But once you break it down, it becomes pretty easy to find the roast with the right balance of acidity and flavor. 

In general, there are four types of roasts: Light Roasts, Medium Roasts, Medium-Dark Roasts, And Dark Roasts. 

1. Light Roasts

As the name suggests, light roasts are the lightest roasts on the spectrum. However, a lighter roast does not correspond to a lighter flavor. Light roasts are known for their high acid content and bright, snappy taste. Because light roasts maintain more of their natural flavor after roasting, they’re often described as “fruity” or “floral”. Light roasts also boast the highest caffeine level of all the roasts. 

To achieve a light roast, coffee beans are roasted until they’re light brown and their internal temperature reaches somewhere between 356 to 401 degrees Fahrenheit. At this stage, the beans are still hard and dry, without any oil on the surface.

Roasts that fall under the light roast category are as follows.

  • Light City
  • Half City 
  • Cinnamon 

2. Medium Roasts

Medium roasts are the most common roasts in the states– and for good reason. Because they’re roasted for longer, the acidity of medium roast beans is less pronounced and more balanced against the subtle fruity flavors still present in the beans. Medium roasts are also sweeter than light roasts and have a more pronounced aroma. In short, it’s a great all-around roast, perfect for those who like a little bit of the acidic bite in their coffee without sacrificing that rich, sweet taste many of us associate with a good classic cup. 

During roasting, you’ll want to get the internal temperature of your beans to between 410 to 428 degrees Fahrenheit to achieve a medium roast quality. The beans will still be relatively dry at this temperature, but not without a slight sheen from the raised surface oils. 

Common medium roasts include: 

  • Breakfast
  • American
  • City 

3. Medium-Dark Roasts

If you’re after very little acidity in your coffee, medium-dark roasts might be more your speed. At this stage of roasting, the coffee beans begin to caramelize, bringing out richer, deeper flavors at the expense of the brighter acidic notes you get with lighter roasts. Medium-dark roasts are associated with smoother tastes like chocolate and caramel and are often preferred by those who are after a bolder-tasting coffee. 

A medium-dark roast is a little trickier to achieve due to its rather small temperature window of 437 to 446 degrees Fahrenheit. At this stage, the beans become noticeably oily and begin to turn a deep, rich brown color. 

 Here are the roasts that fall under the medium-dark umbrella: 

  • Full City
  • High 

4. Dark Roasts

This roast is for those who want a coffee with little to no acidity. At this stage, the natural characteristics of the beans are replaced almost entirely by the flavors imparted during roasting. This means there is practically no acidity in the beans, which instead have a very bold or even bitter taste. Besides the strong smokey flavor imparted by the high temperature of the roast, dark roasts are notable for containing notes of dark chocolate. 

When it comes to dark roasts, it’s best to leave the roasting to the professionals. To achieve a proper dark roast, the internal temperatures of the beans need to get up to around 464 to 482 degrees Fahrenheit. At this point, the beans begin to take on a charred, almost black look with an oily sheen. They’re also in danger of scorching, or worse, catching fire! 

Dark roasts include:

  • Continental¬†
  • New Orleans
  • European¬†
  • Espresso
  • Viennese¬†
  • Italian
  • French

This is also the roast level most prone to becoming a little too bitter if not roasted correctly. If you do decide to go with a dark roast, be sure to grab high-quality beans to avoid an unpleasant tasting coffee. 

Tim S.

Tim loves roasting, brewing, and experimenting with coffee. After years of perfecting this craft, working as a barista, and owning a small coffee service in college, he has decided to share his knowledge with the world.

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