Reasons, Qualities, Differences

Reading time: 7 minutes. This article is a short blog post. You can find the detailed blog article here on our Swiss website.

Anyone who has ever drunk coffee on holiday knows this: coffee is prepared differently everywhere and tastes different in other countries. In Central Europe, dark roasted espresso is considered "proper espresso". On the other hand, in the USA, for example, you can find shops where an underextracted, light, extremely acidic espresso is often sold and liked 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. So whether we like coffee with a high acidity largely depends on whether we are used to acidity in coffee or not. Thus, an Italian might grimace at a low acidity, whereas a coffee farmer from Nicaragua would barely be able to get an espresso down without acidity.

Acidity in coffee divides opinions and palates

Therefore, it is advisable to approach acidic coffees cautiously. After a few more acidic espressos, you might notice that acid-poor coffees now lack liveliness. It's not about acidity itself, but about the balance and equilibrium between acidity and sweetness. If, despite a few attempts, you still shy away from acidity, then at least you'll know you tried.

Sour or Acidity? The pH value of coffee

It is worthwhile to refer to English when describing acidity in coffee. "Acidity" in coffee is desirable, whereas "sour" is a negative description that we want to avoid in the beverage. So-called acids can be detected in coffee in a differentiated way. 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 is between 4.85 and 5.1. The lower the value, the more acidic the liquid. 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 as acidic as coffee (pH 5).

However, the perceived differences in acidity in coffee are not truly measurable. An acidic 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 green coffee, it is primarily chlorogenic acids that influence our beverage. They make up 6-7% in Arabica and up to 10% in Robusta. Compared to caffeine (1-2%), they therefore occupy a large part of our beverage.

These chlorogenic acids are partly altered during roasting and break down into bitter-tasting chlorogenic acid lactones, but some also remain. The longer a bean is roasted and the darker it becomes, the fewer acids remain. Below, we'll introduce you to five acids in more detail.

• Citric acid: Occurs in every coffee, is naturally present in the plant's metabolism, and tastes like lemon, lime, orange.
• Malic acid: Tastes like apples, pears, or rhubarb. Is a bit smoother and more balanced than citric acid.
• Phosphoric acid: A mineral acid. Is a bit tart and sparkling. We often find it in Kenyan coffees.
• Acetic acid: A fruity acid, but only delicious in very small doses.
• Lactic acid: Reminiscent of the acidity in quark. Tart, sour, and heavy.

Acids become interesting when they occur in combinations. We then speak of complex, multi-layered acids. If the acidity is not accompanied by sweetness, the coffee is usually of inferior quality and simply doesn't taste good. A coffee completely without acidity tastes flat and empty. Similar to a white wine without acidity.

Where does the acidity in coffee come from?

Plant and cultivation

The coffee plant grows through what is known as cellular respiration. This also produces the cherries and generates various acids as a byproduct. The growing conditions influence the type and amount of acids. The temperature of the growing region is particularly crucial here. Growing areas located further from the equator produce slower-growing coffee plants due to their climatic conditions. These slow-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 slower-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 notes. However, the differences between the various subgroups are rather small and difficult to taste.

Post-harvest processes

There are differences in the post-processing of coffees. After picking, they are further processed in various ways. Pulped, fermented, and washed coffees can develop more acidity than those dried in the cherry. The storage of the cherries can then influence the acetic acid content. However, post-processing of coffees changes the amount of acids less, but rather adds new aromas to the coffee's spectrum.

Roasting

As described earlier, higher temperatures and longer roasting times minimize organic acids in the bean. While acetic acid reaches a short peak during roasting, it, like the other acids, decreases during the course of roasting. Depending on what the roaster wants to achieve, he accentuates the various acids in the coffee through his roasting.

Preparation

The factors described above influence the type of acids in coffee. Preparation, on the other hand, influences the quantity of acids in coffee. Important parameters for this are the grind size, brewing temperature, brewing pressure, flow rate, and brewing time.

Water

The hardness of the water can also affect the acidity in the drink. Hard water (with high alkalinity) buffers the acids and the coffee tastes rather bland. If this is the case for you, read our reports on water filtration.

Type of beverage: Acidity in espresso, filter, and automatic machines

It is also crucial what kind of 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 roast or preparation, it will knock your socks off. Acidity in filter coffee, however, can be very pleasant and refreshing, as filter coffee has far fewer dissolved coffee particles per milliliter of beverage.

In our acidic espresso blends, we only use beans that also have a distinct sweetness. In this interplay between acidity and sweetness, the acidic components unfold their full and delicious effect.

Caution is advised when an acidic coffee is used in a fully automatic machine. These machines usually brew coffee below 90°, which significantly accentuates the acidity. So, if you choose a light roast, you might have difficulties with a fully automatic machine.

We coffee makers like coffees that don't hide their acidity. That's why we work with green coffees that naturally bring this acidity. Our challenge is to positively introduce acidity into the beverage through sweetness, to make it exciting and complex.

However, not everyone likes these light roasts. That's why we also offer classic nutty-chocolatey roasts, such as our APAS or Henrique from Brazil.

We want to dispel the bad reputation of acidity in coffee, so we try to describe acidity in coffee as something positive and exciting. However, since we are sure that every taste is different, no one should frantically try to convince others 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, for example, could be described through fruit associations. In our El Colibri, a Peruvian coffee, we find tartaric acid. If you think of wine, you will certainly not try the coffee, but if we think of grapes, which are also full of tartaric acids, we get much closer to the point. Our plea is therefore: Away from the pure acidity-bitterness discussion. Coffee is so much more than a more or less acidic beverage.