To some, coffee is a necessity for everyday life. In cold winter, a cup of hot coffee can definitely make you feel warm inside.

 

We often consider the taste of coffee as "bitter", but do you have any idea of "sour coffee"?  Some may think the sour taste of coffee is unusual and unpleasant. But why is it?

 

Actually, the level of the acidity in coffee is relevant to the origin, brewing method and extraction of coffee beans. And the acidity is one of the evaluation factors for specialty coffee worldwide. Let us check it out!

 

 

Sour as Flavor

 

 

This Coffee Taster's Flavor Wheel made by Specialty Coffee Association of America and World Coffee Research may help us to get what various flavors of coffee tastes, such as sweet, sour, floral, fruity, spices and so on. And for fruity and sour flavors, there are orange, berry, lemon, apple, grape, etc. These complex flavors give the coffee its unique characteristics!

 

 

The Origin of Sourness

 

 

Acidity can be directly attributed to organic acids found in the coffee beans, such as citric acid, malic acid and those sour aromatics. And they distinguish themselves by different environmental factors like weather and altitude in the growing regions of coffee beans. For example, Ethiopian coffees often have a densely sour berry flavor because amounts of acids are reserved in coffee beans growing with high altitude.

 

 

Acidity

 

 

Roasting: Our perception of sour taste in coffee has a root in roasting. Light roasts are more acidic than dark roasts, making them lean towards the sour side. A light one will have a pH of 4.5-4.7, while a dark one can be higher than 5.5. So if the coffee is dark roasted, you may not find it sour.

 

 

Extraction: If the coffee is under-extracted it will taste sour because the fruity acidity is extracted early in the brewing process, whereas other balancing flavors are extracted later in the process. So the coffee has an excess of acids and they are not balanced with the sweetness and even some bitter notes. What is more, if you're familiar with coffee brewing methods you may know that factors like temperature, grind, brewing time, and water weight may also influence the acidity.