You've probably already heard of the term "acidity of coffee." This is one of the leading characteristics of the grain by which one can judge its quality. Acidity or sourness, as it is often called at the household level, is most clearly manifested in Arabica. But in another type of grain - robusta - acids are not felt.
On the one hand, acidity is a normal characteristic of coffee, as well as for other tropical fruits and berries. On the other hand, not every coffee has acidity, and because of this, it is not clear why acidity is bright in one coffee, in another, it is not at all, and on what it depends.
What affects the acidity in coffee?
Initially, each type of coffee bean has its own level of acidity. But it can change - it depends on the growing conditions of the trees, the method of processing and preparation. For example, on highland plantations more acidic coffee is harvested than on plains, and the lighter the roast of such beans, the more acids you will feel in the drink.
The intensity of acidity depends on four factors: the height of the coffee, the way the beans are processed, the degree of roasting, and preparation. Now, in order:
Growth height. The higher the coffee grows, the greater the difference between day and night temperatures and the lower the oxygen level, because of this the coffee matures longer, more organic acids accumulate in the berry, and the grain itself becomes denser.
In Arabica, the bright acidity is inherent in nature. In robusta, acids are present in very small quantities. This difference is due to the genetic characteristics of the trees themselves, as well as to the fact that robusta grows much lower than Arabica.
Processing method. Washed coffee is more acidic than naturally processed coffee. This is because, firstly, with natural processing, more sugars from the gluten have time to pass into the grain, and secondly, with different types of processing, fermentation by bacteria proceeds in different ways and this affects the taste.
The processing methods of honey, half-washed, wet-hall, and pulp-natural, in terms of their influence on the intensity of acidity, are between washed and natural - coffee is obtained with moderate acidity.
Roast degree. All flavor components appear in coffee as a result of chemical reactions that occur during roasting. Acidity is initially present in the grains, but not formed.
It changes during roasting, but it is not linear. From the start of frying until the start of the color change, the amount of acids increases, then they develop, become more complex, complex, and sweet. Starting with a light to medium roast, organic acids begin to break down, and the darker the roast becomes, the less acidity remains in the coffee, but its saturation and strength increase.
It is important to roast the coffee so that the acidity is sweet, not aggressive, and all descriptors are maximized. With a dark roast, the difference between expensive and cheap coffee is lost: complex “enzyme” descriptors go away, only the roasting and caramelization flavors remain. Therefore, if they take high-quality grain without defects and try to reveal its tastes, the coffee is roasted light enough, and this reveals the acidity.
Cooking. The coffee components do not dissolve at the same time during preparation. Fruit and organic acids dissolve first. Then - light components that give the coffee the taste of chocolate, vanilla, and caramel. In the end, heavy components dissolve tobacco, malt, wood, and others.
If, for example, reduce the cooking time, increase the grind, or lower the temperature - decrease the total extraction percentage, the acidity will appear brighter. Because of this, espresso coffee is always obtained with more pronounced acidity, and in order to make the drink more balanced, espresso coffee is roasted a little darker and according to different profiles.
What are the acids in coffee?
To begin with, the two most significant groups should be distinguished - organic and inorganic.
Organic acids - appear naturally as a result of the cellular respiration of plants and their fruits. Strongly dependent on the height of the trees. So, in some varieties of high-mountain arabica, more than two dozen acids are present.
Inorganic acids - appear as a result of human activities. Depends, for example, on what fertilizers were applied to the soil to feed the trees.
Acidity is the basis of the richness of coffee. But in taste, it is not the intensity of acidity that is important, but its quality. Acidity is of four types:
Most often, coffee contains all four types of acidity in different proportions, except for orthophosphoric acidity. It is found in robusta and some types of arabicas that grow in soils with a high phosphate content. For example, in Kenya.
Citric acid is the most obvious on the list, the most readily discover even if you are not a professional in the coffee industry. Citric acid is very bright and juicy, most pronounced in green coffee, and decreases with increasing roasting intensity.
Malic acid - helps to achieve a tart and viscous sourness in the taste of the drink. It is one of the most valuable acids for specialty arabica.
Acetic acid - in itself is not very attractive, in large quantities, it can spoil the impression of the drink (this happens if the coffee is poorly fermented). But at the same time, the acetic acidity helps in shaping the pleasant, complex taste of the tasting coffee cup.
Tartaric acid - like vinegar, will spoil the taste if too much.
Quinic acid - manifested during the roasting process. Its concentration increases in stale, chilled coffee, as well as in dark roasted varieties. You can see it yourself - it will be enough to taste a cold espresso.
Phosphoric acid is most pronounced in Kenyan Arabica with its bright currant notes.
Acidity is a completely normal characteristic of taste. Its intensity depends on the height of the plantation, the processing method, and the degree of roasting.
If you find low acid coffee or low caffine coffee, then try to taste it and find familiar flavors in it. If you do this regularly, your taste experience will grow, and each time you will find more and more new notes.
The main thing is that there is no pronounced bitterness in the coffee. The coffee should be sweet and acidic.