Acidity in Coffee

In a previous article, I talked about bitterness in coffee, so now I will talk about acidity, which is a little more complex than bitterness. After that article, we concluded that bitterness is a negative characteristic of coffee and that if it is present, it is because something along the entire coffee chain (from the plant to your cup) has not gone well.

With acidity, it is different, mainly because when we refer to it, I believe that not all of us are thinking about the same thing. There is a lot of confusion about the term and what it means in terms of coffee.

What is acidity, and why do we perceive it in coffee?

Coffee beans, which are seeds, have in their chemical composition many acids, and most of them are organic, which contribute to the final flavor of the final drink. And they are the same ones that we can find in many foods, such as in a great variety of fruits, yogurt, or vinegar, among others.

The main acids in coffee are citric acid, malic acid, tartaric acid, and acetic acid.

Types of acids present in coffee

Identifying the types of acids that we feel help us determine a coffee’s flavors or tasting notes. I have already explained in the article how to start drinking coffee and appreciate acidity.

Citric acid

As its name indicates, it is found in most citric fruits, such as lemons, oranges, tangerines, etc., and is the easiest to identify due to its characteristic flavor.

The acidity of coffee
The acidity of coffee

Malic acid

It is the one we commonly feel with characteristic juiciness and softness, in greater quantity, in a green apple. We can also find it in lime and grapefruit, associated with a green fruit that has yet to ripen.

Therefore, malic acid is found in everything green: apples, grapes, kiwi, etc. When the fruit ripens, this acid becomes less present.

Tartaric acid

One of the most interesting to me. We can find it in higher concentrations in grapes, but it is also present in bananas, blueberries, and seeded fruits such as plums, cherries, etc.

The characteristic of tartaric acid is that it causes great salivation in the mouth and leaves an astringent aftertaste.

Acetic acid

It has a characteristic vinegar-like taste and odor. If it has little concentration, it can be like a bright acidity, but if it has a lot, it can feel like something already fermented, and if it is mixed with other flavors, such as sugar, it can give a taste like wine or champagne.

Is perceiving acidity in coffee a good thing?

Now that we know that acidity is naturally present in coffee beans due to its chemical composition, we should know if it is good or not to perceive it in coffee. Well, it is a resounding yes; it is a very sought-after attribute by all coffee professionals since acidity can contribute many positive qualities to the cup.

The problem is that many confuse the term acid with sour, which is the word we use to define negative acidity. Acidity must be present and perfectly balanced with coffee’s other flavors, such as sweetness and bitterness.

When the coffee has no acidity, it is described as flat, and when it is sour, something is wrong. This generally concerns the preparation, a subject we will see later.

Why do some coffees have more acidity than others?

To a great extent, this is defined by the cultivation and harvesting of coffee. The coffee tree’s variety, the plant’s genetics, and how that variety adapts to the planted place influence the bean’s acidity.

Each soil is different and has its characteristics, in addition to the climate and altitude (the elevation where it is located is key). At higher elevations, temperatures are cooler, giving the plant more time to ripen its fruit, which causes more complex flavors and acidity to develop.

Processing; how these seeds are separated from the fruit. Washed coffees are pulped and rinsed with water, eliminating the sugar found in the pulp, which brings out the acidity. On the other hand, the coffees with natural processes are left to dry inside the whole fruit, increasing the fruity and sweet flavors of the coffee and slightly dulling the acidity.

Coffee with washed process vs. Coffee with natural process
Coffee with washed process vs. Coffee with the natural process

Acidity can also be present during roasting, another important part. If we start with a low-altitude coffee, with a natural process and little acidity, as many coffees from Brazil, for example, there is nothing we can do during roasting to add acidity; if the acidity were not in the beans, it would not appear now.

But the opposite can happen if we have coffee that already presents many of these acids. Still, if we roast it badly and give it a dark roast, the acidity disappears, and we are left with a flat coffee, roasted taste, perhaps smoky taste, and other uninteresting flavors.

For this reason, it is very important to roast and find roasters that give a correct profile to the coffee and not to go beyond a medium roast if we want to preserve those characteristics so sought after from the farm, where a lot of work was done to obtain such a good quality coffee, a bad roast kills it and throws all that work away.

Does the preparation of the coffee determine the acidity?

Is there anything we can do to increase or decrease the acidity in the preparation? In this case, something similar happens to what happens with roasting. If the coffee has no acidity, to begin with, there is nothing we can do to increase it. If it already has acidity, only by giving the coffee a good extraction will we obtain all those good acids, with all the other flavors in a perfect balance.

A myth goes around saying that “you will obtain a higher acidity by using a coarser coffee grind,” and this is not necessarily so; it all depends on the extraction.

Coffee grinding and extraction
Coffee grinding and extraction

For example, if we prepare coffee in a French press, we are going to use a much coarser grind than to prepare an espresso. This does not mean that the coffee from the press will have a higher acidity since it has to do with the contact time that the coffee will have with the water in the press, 4 minutes, and an espresso, 30 seconds.

What does happen is that, at the moment of calibrating, if you use a grind a little coarser than you needed, the coffee will not be completely extracted; it will be extracted, and we will feel a sour taste (which some confuse with acidity), but at the same time also a little watery and almost without flavor.

While grinding finer or leaving more contact time, the coffee continues to be extracted, and we obtain all the flavors without diminishing the acidity. Still, if we go too far and leave it much longer or grind very fine, we obtain a bitterness and astringency that kills the acidity and sweetness of the coffee.

Variables that affect the acidity

There are two issues to take into account when preparing coffee that does make the acidity to be perceived more or less. These are:

  1. The water that you use to prepare the coffee. If the water is very hard and has many minerals, the extraction will be very fast, but it can result in a buffer for the acids, dulling the perception of acidity a little. If, on the other hand, the water is very soft, it slows down the extraction and may not extract all the flavors. It is a matter of finding a middle ground. See this article on the water for coffee.
  2. The water temperature plays a very important role in the perception of acidity; the higher the temperature, the more and faster the coffee will be extracted. But yes, certain compounds, mainly acidity, are not extracted if we do not use a very high water temperature. Therefore, I always recommend using it immediately after boiling and adjusting it with the other variables if necessary.

Conclusion

I hope that with all this information you will give a second chance to the acidity of the coffee if you do not like it. If you bought a good quality coffee and complained that it is acidic, remember what I told you: change the water, try grinding it finer with a higher water temperature, and extract more of that coffee.

If you like acidity, with these guidelines, you will know where to aim in the purchase of coffee to savor it. And do not neglect these preparation issues either.