Coffee shouldn't be sour/acidic or should it be? The discussion abou t coffee and its acidity has been dividing coffee afficionados ever since. There is hardly a perfect espresso for everyone. The taste of acidity is perceived as disturbing for some, while others cannot imagine their coffee without it.

In this article we explain what acidity is, why it is such a controversial topic and what it has to do with Horizonte Coffee Roasters.


Acidity in coffee, what is behind it?

Let's first clarify the terminology. In German language the word sour is often negatively connotated. Sour coffee is bad. Sour or acidic coffee is associated with the pH value. However, a lightly roasted sour or acidic coffee has the same pH as a bitter dark roast. So, whether a coffee is sour cannot be generalized. On the other hand, the word acidity depicts more of a neutral evaluation and is a description of the flavor profile. However, a coffee with acidity does not necessarily mean that it is sour.

The coffee has a pH value of around 5 (more or less, depending on the coffee), so it is generally sour. A lightly roasted African coffee with a lot of perceptible acidity does not necessarily have to have a lower pH value than a dark roast with little acidity. This can also be compared to Coke versus household vinegar. Both have a pH of 2-3, but Coke tastes sweet compared to household vinegar.

An espresso is a highly concentrated drink, so the consumer is very sensitive to the noticeable acidity, which is less the case in a filter coffee in which the concentration is lower.

There are up to 40 detectable acids in coffee. It is important to distinguish between chlorogenic acid and other finer, more intensely flavored acids

Chlorogenic acid makes up most of the acidity in coffee beans. This acidity is a powerful natural antioxidant and is responsible for how strongly or rather uncomfortably sourness of the coffee tastes.

The other finer, flavor-intensive acidities are relevant for the typical coffee taste and make the coffee interesting, lively and supports the flavor profile.

Depending on the type of coffee, the amount of chlorogenic acids, which have a direct influence on the bitterness in the coffee, differs. Most of the acids are already destroyed by roasting, the longer you roast, the more the acidity decreases.


The formation of acidity

•  Cultivation / type of coffee
  For example, Robusta beans have less acidity than Arabica. This is because due to the low altitude that allows the beans to grow faster. Through this rapid growth process the bean is not developing that well and it has a little less of everything (flavors, acidity, protein, sugar, density, complexity, etc.) compared to a slow-growing high altitude Arabica coffee bean.
  
  
•  Post-harvest process
  How the coffee cherries are processed after they have been picked also has a major impact on the taste. Coffees that are dried with the skin of the cherry (natural coffees) tend to have less acidity than cherries that are depulped, fermented/washed and then dried. (washed coffees).
  
  
• Roasting
  The longer the roasting and the higher the final temperature, the less acid the coffee has. Acetic acidity is the only acidity with a short peak after the second crack. All other acidities break down over the duration and increasing temperature of the roasting process.
  
  
• Preparation
  The brewing time, grinding size, the brewing temperature and the pressure have a major impact on how much acidity ends up in your cup. Water with high alkalinity will neutralize the acids in coffee. 
  
  

Why is acidity needed?

• Coffee without acidity tastes similar to stale Coke, or stale white wine.
• Acidity makes coffee lively, fresh and adds complexity.

A matter of taste and/or learned?

In southern and central Europe, good coffee is expected to be bitter. An Italian dark roasted espresso is considered really good coffee. Due to our cultural and social background, our eating habits are different, whether the coffee tastes bitter or acidic is not just a matter of taste, it is much more about how we grew up with it and how we learned to consume it. Therefore, this does not only apply to taste and consumption habits.


Acidity and Horizonte Coffee Roasters

The acidity is only part of the taste experience in coffee. It's about the balance, along with other components like bitterness, sweetness and flavors which are influenced by bean type, post-harvest process, roasting and preparation.

At Horizonte Coffee Roasters, we want to integrate the acidity into the coffee as much as possible, for it to support the aromas and freshness of the coffee.

We learned this in various courses (thanks kaffeemacher.ch) and endless testing sessions in our roastery.

- Roast profile pronounced acidity. Short direct and not flattened around 205°C

- Roast profile reduced acidity. Long and flattened after 205°C