The acidity of coffee: virtue or flaw?

I maestri della tostatura media
We often hear about acidity in coffee and just as often associate it with a negative feeling. But is acidity a plus or a minus? What do I need to know about acidity?

In this article, I would like to clarify what coffee acidity is, where it comes from, and what it depends on, in order to taste more consciously and more pleasantly every coffee you drink.

So let’s start with the definition: sourness is one of the five tastes, along with sweet, salty, bitter and umami. It is perceived by our body through the taste buds of the tongue.

Then looking at the scale of pH levels ranging from 0 to 14, in which 7 is the neutral value, coffee takes a value of 5, thus acidic. Just like coffee, all foods have a particular and specific chemical composition and degree of acidity.

In our case, coffee beans have dozens of acids, the main one being chlorogenic acid.

I will anticipate that most of these acids, reduce as temperature increases.

These acids are essential in our cup!

In fact, in addition to making our coffee more complex, as we will find out in a moment, they also have important antioxidant and anti-inflammatory properties, which have positive effects on our bodies.

After introducing the term and explaining it chemically: what does the acidity we find in coffee depend on?

Acidity depends on several factors:
  • the species/variety
  • the altitude
  • the terroir
  • the processing method
  • the degree of roasting
  • the extraction
In general, it can be said that the Arabica species is more acidic than the Canephora (Robusta) species.

In addition to the macro differences between Arabica and Robusta, there are other micro differences between different varieties of the same species.

The above can also be applied to mixtures.

So if you buy a blend with a higher percentage of Arabica, you will get a fresh, pleasant acidity in the cup, just as happens in our Allegro blend.

Whereas if you buy a blend with a higher percentage of robusta, it will tend to make your cup taste more pushed toward bitterness, for example like our Stretto blend

o Lively.

This also depends on the altitude at which the coffee was grown. Again, in general, coffees grown at higher altitudes are more acidic, compared to those harvested at lower altitudes. This is because it tends to be because the higher you go, the more rocky and/or richer the soil becomes in minerals, some of which have an acidic taste.

This also explains the previous statement, since Arabica quality coffees are grown from 900 m above sea level, up to 2000-2200 m; while robusta quality coffees are found in the lowlands, up to about 900m.

So we can say that acidity depends on the terroir in which our coffee plant grows, just as it does with grapes for wine.

To give a concrete example, an Ethiopian or Kenyan coffee will definitely be more acidic than a Brazilian or Vietnamese coffee.

In addition, acidity also depends on the processing method that takes place in the plantation.

In fact, two main types of processing are adopted once the drupes are harvested from the plants: natural and washed.

Leaving out, at least in this context, an in-depth discussion of the further types of processing as well, with the first, dry, the grains extracted from the drupes are allowed to dry in the sun. This imparts greater sweetness in the cup.

In the second, the washed one, on the other hand, the grains are allowed to ferment in water and then go to be washed and only then dried in the sun. This imparts more acidity in the final result.

But not only that!

As we had already anticipated, acidity also depends on the level of roasting that the roaster applies to the grains.

The concentration of acids in coffee beans decreases with increasing temperatures. The lighter the coffee is roasted, the more acidic it will be when extracted in the cup, and conversely, the more it will be roasted, the less acidic it will be, preferring hints of bitterness and even burnt, if the roasting is really very strong.

(The leftmost bean is raw, followed by a light roast coffee, the middle one is medium roast, right after that you can see a dark roast bean, and to the right the very dark or Italian-style roast.)

Finally, if we consider an espresso coffee, acidity also depends on the correctness of the extraction.

Let me explain: an under-extracted coffee will be more acidic than one extracted in the correct ways and times and also than one over-extracted. This is because when coffee is under-extracted, it means that the water has “passed” through our ground coffee too quickly and thus failed to extract all the substances contained in the coffee, such as fats, sugars, and so on. It extracted almost only the acids, the first ones to go down into our cup.

Now it’s time for the question you’re surely asking yourself: is acidity in coffee a plus or a minus?

Sourness in coffee is a virtue!

It is one of the most representative parameters for understanding the difference between a complex coffee and a flat, characterless one.

A right level of acidity, and I emphasize right, in fact manages to give the drink that freshness typical of citrus.

At the same time, however, like everything: too much is too much! It should never be excessive or too pungent, in which case it would be considered a defect, as much as excessively bitter coffee with an empyreumatic aftertaste, i.e., ashy and burnt.

In addition, the acidity can also be balanced by sweeter notes, such as those of ripe pulp fruit, or the typical sweetness of berries. Or from more toasty notes of chocolate, toast, caramel, etc.

The art of balancing resides in the hands of the roaster, who for each specific single-origin tries and tests, to arrive at the perfect roasting curve for those specific beans, to be able to bring out all the positive flavor notes to the fullest.

However, this is only feasible with a medium roast, as a light roast brings out more of the sour notes, while a dark roast makes the coffee only bitter, going to hide all other flavors.

That is why we at Caffè Ernani opted for the Medium Roast.

However, sourness is often considered a negative sensation, partly out of habit, because too often simply bitter coffees are served, and partly because it is confused with astringency or sourness.

This is because we have memorized that when we eat a lemon, an acidic food par excellence, we also feel astringency, that is, that feeling of a watery palate, we feel like a sandy sensation, and saliva is reduced, drying out the mouth.

This feeling, however, in coffee is considered a flaw.

So a coffee can be acidic, but never astringent!

I conclude by saying that everything I have said so far applies on an objective level. After that, subjectivity comes into play: each of us can appreciate different coffees, coffees that are more pushed on acidity or coffees that are more balanced. For example, I prefer very acidic coffees with very intense citrus aromatic notes.

What type of coffee do you prefer? Email me at and tell me your opinion!

Marketing, E-commerce e Social Media Manager
Coffee Lover


Martina Mazzoleni

Marketing, E-commerce e Social Media Manager Coffee Lover

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