Espresso coffee cannot be called espresso if it is not finely crowned with a thin layer of thick, delicious crema. But how does the crema form? And what can we do to make it even more irresistible?
How does coffee crema form?
Chemically speaking, espresso crema is formed by a very light emulsion of very fine coffee particles and microbubbles of carbon dioxide; the latter, sticking to the fats and oils that make up the coffee, rise to the surface of the drink, colouring it a warm hazelnut colour.
The espresso’s crema is created by the action of hot water and pressure, which, coming into contact with the ground coffee blend, allow the carbon dioxide present in the bean from the roasting stage to be released.
This is why the pressure of the coffee machine is the first element to consider if you want to produce crema. And it is also essential to buy roasted coffee because it is the roasting process that releases carbon dioxide into each coffee bean.
The barista’s experience can also play a decisive role in creating great coffee because the degree of grinding, the pressure applied to the ground coffee and other details can change our perception.
Crema or foam?
To call foam the soft crema that decorates coffee and makes it even more delicious is a real insult to lovers of the art of coffee making. Foam is a real defect of coffee, something to run away from.
But what is the difference between crema and foam?
Unlike foam, crema does not have bubbles, has a softer consistency and is very pleasant to the palate.
Although many use the two terms as synonyms, it must be remembered that they are two different consistencies, one to be appreciated, the other to be categorically rejected as a symptom of coffee that has not been made properly.
To achieve a visually appealing and tasty crema, which serves as an indicator of good coffee, it’s essential to consider the speed at which the espresso is prepared:
- A crema with a small number of very large bubbles suggests that the coffee was prepared quickly and will likely have little body.
- Conversely, a too-thick and dense crema indicates that we are dealing with a coffee almost certainly burnt and prepared too slowly.
What coffee species produces the best crema?
The two species we are going to talk about are Arabica and Robusta. It must be said, however, that there is no coffee bean that objectively and regardless makes more crema than another.
Still, experts in coffee-making seem to be prepared to admit that Robusta makes, at least in most cases, more crema than the Arabica species.
Robusta Coffee Crema
Robusta coffee adds body and structure to the drink and produces a frothy crema with large bubbles that tend to disintegrate quickly. The woody fibres in Robusta beans generate dense crema, but it’s lower fat content than Arabica prevents it from lasting long on the surface.
The crema has an orange-peel or sand dune appearance and can hold sugar crystals on its surface for a few minutes. Blends with a high concentration of Robusta create crema that initially supports weight but then bursts due to the weight of sugar.
A good quality Robusta species are necessary for excellent crema, as the percentage of fat and fibre influences the result.
Arabica Coffee Crema
Arabica offers a rich aroma and produces a reduced crema layer that is more compact, elastic, and brightly coloured. The crema comprises small, shiny bubbles due to the oils and fibres present in Arabica coffee.
Unlike Robusta, this crema is durable, lasting several seconds after a teaspoon of sugar is poured. The crema dissolves after a few minutes, starting from the central area.
Blends with a high concentration of Arabica create crema that can conceal the coffee from view, giving a pleasant visual appeal to the drink.
In conclusion: which beans to choose?
Finding the perfect coffee blend does not automatically mean getting the best crema: skill, experience, and many other variables that are not under our strict control contribute to creating the crema, the crowning glory of the perfect espresso.
However, in addition to finding the right crema, it is certainly essential to start with a mix that is of high quality and meets the customers’ needs.