Reasons, Qualities, Differences
Reading time: 7 minutes. This article is a short blog. You can find the detailed blog post here on our Swiss website.
Anyone who has had coffee on vacation knows this: Coffee is prepared differently everywhere and tastes different in different countries. In Central Europe, dark roasted espresso is considered the "proper espresso". On the other hand, you can find shops in the USA, for example, where an under-extracted, light, highly acidic espresso is frequently sold and enjoyed by people.
Acidity in Coffee: All a Matter of Perspective?
Taste is learned. What we find delicious is part of our socialization and our experiences. Whether we like coffee with a high acid content depends largely on whether we are accustomed to acidity in coffee or not. So an Italian might make a face at low acidity, whereas a coffee farmer from Nicaragua can hardly get an espresso down without acidity.
Acidity in Coffee Divides Spirits and Palates
For this reason, it is advisable to approach acid-forward coffees cautiously. After a few more acidic espressos, you might notice that acidic coffees lack the liveliness. It's not about acidity itself, but about the balance and harmony between acidity and sweetness. If, despite several attempts, you still distance yourself from the acidity, then at least you'll know afterward that you tried.
Sour or Acidity? The pH Value of Coffee
It's worthwhile to refer to English when describing acidity in coffee. "Acidity" in coffee is something desirable, whereas "sour" is a negative description that we want to avoid in the beverage. So-called acids can be differentiated in coffee. There are up to 40 different ones.
The term acidity refers to various flavor notes in coffee. "Sour," on the other hand, describes the pH value of the coffee.
The pH value is a chemical value that indicates how acidic a liquid is. Coffee ranges between 4.85 and 5.1. The lower the value, the more acidic the liquid. For example, tomato juice has a value of 4, and lemonade even 3. One point on the pH scale makes a difference of x10. So lemonade (pH 3) is 100 times more acidic than coffee (pH 5).
However, the perceived acidity differences in coffee are not really measurable. An acid-forward roast has the same pH value as a dark, rather bitter roast.
Which Acids Do We Taste in Coffee?
Of the 40 different acids in raw coffee, it is primarily chlorogenic acids that influence our beverage. They account for 6-7% in Arabica and up to 10% in Robusta. In comparison to caffeine (1-2%), they take up a lot of space in our beverage.
These chlorogenic acids are partially altered during roasting and break down into bitter-tasting chlorogenic acid lactones, but some of them are also retained. The longer a bean is roasted and the darker it becomes, the fewer acids remain. Below, we'll introduce you to five acids in a bit more detail.
- Citric acid: Occurs in every coffee, naturally occurs in the plant's metabolism, and tastes like lemon, lime, orange.
- Malic acid: Taste like apples, pears, or rhubarb. Slightly more mellow and balanced than citric acid.
- Phosphoric acid: A mineral acid. Somewhat more astringent and prickling. We often find it in Kenyan coffees.
- Acetic acid: A fruity acid that, however, is only delicious in very small doses.
- Lactic acid: Reminds us of the acidity in quark. Herby, sour, and heavy.
Acids become interesting when they occur in combinations. We then speak of complex, multi-layered acids. When the acidity is not accompanied by sweetness, the coffee is usually inferior and simply doesn't taste good. Coffee without any acidity tastes flat and empty. Similar to white wine without acidity.
Where Does the Acidity in Coffee Come From?
Plant and Cultivation
The coffee plant grows through so-called cellular respiration. This produces the cherries and creates various acids as a byproduct. The cultivation conditions influence the type and amount of acids. Above all, the temperature of the growing region is decisive here. Growing regions that are farther from the equator produce coffee plants that grow more slowly due to their climate conditions. These slowly growing coffee plants are more focused on their reproduction and produce cherries that contain more proteins, sugars, fats, and also acids. The caffeine content of these more slowly growing plants, however, is lower.
Species and Varieties
Arabicas have a higher acid content than Robustas. Within these two varieties, there are many subgroups. Parainemas, a hybrid from Honduras, for example, shows significantly more citric acid notes. However, the differences between the various subgroups are rather minor and barely noticeable to the palate.
Post-Harvest Processes
There are differences in the post-processing of coffees. After picking, they are further treated in various ways. Depulped, fermented, and washed coffees can develop more acidity than those dried in the cherry. The storage of cherries can then influence the acetic acid content. However, post-processing changes the amount of acids less; rather, it adds new aromas to the coffee's spectrum.
Roasting
As already described, higher temperatures and longer roasting times minimize the organic acids in the bean. Acetic acid does reach a short peak during roasting, but, like other acids, decreases in the course of roasting. Depending on what the roaster wants to achieve, they accentuate the various acids in the coffee through their roasting.
Brewing
The factors described above influence the type of acids in the coffee. Brewing, on the other hand, influences the amount of acids in the coffee. Important parameters for this are the grind size, brew temperature, brew pressure, flow rate, and brew time.
Water
The hardness of the water can also influence the acidity in the beverage. Hard water (with high alkalinity) buffers the acids and the coffee tastes rather flat. If that should be the case for you, read our reports on the subject of water filtration.
Type of Beverage: Acidity in Espresso, Filter, and Fully Automatic Machines
It is also crucial which beverage we actually want to drink. Due to the high concentration of dissolved coffee particles, an espresso forgives few mistakes. If it is too sour due to the type of roasting or brewing, it will knock your socks off. Acidity in filter coffee, on the other hand, can be very pleasant and refreshing because filter coffee has far fewer dissolved coffee particles per milliliter of beverage.
In our acid-forward espresso blends, we only use beans that also have pronounced sweetness. In this interplay between acidity and sweetness, the acidic components unfold their full and delicious effect.
Caution is warranted when an acid-forward coffee is used in a fully automatic machine. These devices usually brew the coffee below 90°, which emphasizes the acidity even more. So if you reach for a light roast, you might have a hard time with the fully automatic machine.
We coffee makers like coffees that don't hide their acidity. That's why we work with raw coffees that already bring this acidity. Our challenge is to bring the acidity positively through sweetness into the beverage, to make it exciting and multi-layered.
Nevertheless, not everyone likes these light roasts. That's why we also have classic nutty-chocolatey roasts, such as our APAS or Henrique from Brazil.
We want to remove the bad reputation from acidity in coffee, so we try to describe acidity in coffee as something positive and exciting. However, since we are certain that every taste is different, no one should desperately convince the other that acidity in coffee is exclusively good. Perhaps the old discussions about acidity and bitterness should rather be replaced by a new way of talking about coffee. Acidity could, for example, be described through fruit associations. In our El Colibri, a Peruvian coffee, we find tartaric acid. If you think of wine, you probably won't try the coffee, but if we think of grapes, which are also full of tartaric acids, we're getting much closer to the point. Our plea is therefore: Away from the pure acidity-bitterness debate. Coffee is so much more than just a more or less acidic beverage.
