Characteristics of coffee: astringency and sweetness

Our series of articles dedicated to the characteristics of coffee, designed to help you understand the qualities of our favourite beverage and immediately recognise an excellent coffee as soon as you taste it.

We’ve already seen what roundness and aroma are, we’ve looked in detail at body. Here, we’ll investigate another two extremely important characteristics: the astringency and sweetness of coffee.

The astringency of coffee

The plant-derived tannins in coffee stimulate the mucin protein in saliva, which reduces the ability of the saliva to lubricate the mouth, increases viscosity and generates a sensation of astringency. Astringency is associated with a sour taste that shrinks the tastebuds. Professional coffee tasters define the taste provided by this sensation as being very similar to that experienced when tasting raw artichokes.

Astringency is a tactile characteristic of coffee, which also involves the sense of taste and it is accompanied by another two characteristics: softness and earthiness. Without going into too much detail, it’s enough to say that, like astringency, earthiness is also generated by the reduction of the lubricating power of saliva, and it is associated with a very strong bitter taste. It is not a particularly pleasant sensation and – although not always, since coffee is evaluated based on a variety of factors – it is usually associated with a coffee that is not of excellent quality. 

On the other hand, softness is a positive sensation, associated with that spherical aspect of coffee tasting. It is directly proportional to the quantity of microscopic solids suspended in the coffee and increases in proportion to the quantity of fatty substances dissolved in the beverage. The sensation of softness becomes less marked when bitter and acidic tastes are persistent.

When tasting an espresso, it can be said that you are tasting a quality product when you perceive a sensation of softness, a velvety body, and the right level of creaminess in the mouth. This means that the coffee is not too liquid but not too syrupy either. Its taste should also be enveloping and no one aromatic note should prevail over another, both when sipping the beverage and exhaling.

As we already know, there are two main types of coffee: Arabica and Robusta. Coffee made with Arabica beans contains more oils, which give it acidic, but not bitter notes, because as a coffee that also contains more sugars and less caffeine, it appears sweeter and less full-bodied on the palate. Coffee made with Robusta beans is stronger, more bitter, and has a fuller body. Its aromatic notes are more subtle, but its full body means that the finished product is an espresso with a denser, thicker creaminess than coffee made with Arabica beans.

The sweetness of coffee

Sweetness is related to the sense of taste and obviously the sweet, smooth sensation perceived when you taste a coffee. As we saw above, Arabica coffee is very sweet, because it contains sugars, whereas Robusta coffee is less so.

The perception of sweetness in coffee is often associated with the perception of a fruity taste on the palate and on the tip of the tongue. Professional tasters and roasting houses like ours refer to the sweetness of coffee when they want to describe the intensity of the quantities of sugars perceived when tasting the coffee.

Sweetness is one of the most important properties that make a product high quality and to respect it, the roasting phase is important. A roasting process that is too strong and aggressive almost completely nullifies this property. Our roasts are medium strength because we want to maintain a balance between the levels of sweetness, bitterness, and acidity in our coffee.