Its unmistakable appearance, intense fragrance, and rich strong aroma have made espresso one of the symbols of Italy around the world. Credit for this success goes to the creativity with which Italians have transformed the preparation of coffee: from a simple infusion of powder in hot water to a true art form. In Italy, coffee is not a beverage but a pleasure, a ritual and, above all, a “taste” that is exported and famous around the world.
To the Italians, the term espresso literally means “made on the spot”. It was coined to emphasise the particular method of brewing coffee under pressure, made at the request of the customer using a professional machine. It seems that the method was perfected as a way of shortening preparation time, which was considered too long.
The first prototype of the espresso machine, which was presented at the World Expo in Paris, dates back to 1855. Instead, it was not until 1901 that the first commercial machine was built by Luigi Bezzera, an Italian engineer. The particular extraction method that is used yields a very concentrated beverage with an intense flavour and aroma.
Extraction, which lasts from 25 to 30 seconds, is done by water (softened ahead of time) at a temperature of 88-95°C (190-203°F) and a pressure of 9 atm (128 psi). The volume of the brewed coffee in the cup is about 25-30 ml (3/4 to 1 fl oz).
Let’s take a look at the characteristics of a good espresso.
- Crema: this is the result of the emulsion of gas (CO2) and oils that takes place inside the basket of the portafilter during extraction and is due to high pressure.
- Body: this is the “full” mouthfeel imparted by the oily emulsion, the presence of colloids and tiny suspended particles.
- Aroma: this is the aromatic intensity of espresso due to the high concentration of volatile particles in such a small volume.
The 4M rule for the perfect espresso
Now we can examine how espresso is prepared. We have already pointed out that this involves a kind of alchemy that is highly precise yet extraordinarily simple. This transformation is determined by the so called “rule of the four Ms”, i.e. the combination of four factors that in Italian all begin with an M: blend, grind, espresso machine and the operator’s skills – Miscela, Macinadosatore, Macchina per espresso, Mano.
Each of these elements contributes 25% to making a perfect espresso. Relying on experience and professionalism, the barista chooses the quality blend that, with the right grind and the technology of professional machines, will expertly be transformed into an excellently prepared and served espresso.
Let’s take a closer look at the unique traits of a perfect espresso:
- The temperature of espresso in the cup after brewing is about 75-80°C (167-176° F).
- In Italy, the volume of a regular espresso is about 25-30 ml (0.8-1 fl oz).
- The ideal crema is compact and persistent, with a hazelnut colour. It must never be foamy or weak, nor too light or dark in colour.
- The porcelain cup must be white, tapered in shape, and preheated to a temperature of about 35-40°C (95-104° F). This keeps the crema compact and hot enough to prevent the coffee from cooling too fast.
The espresso crema
This is the emblem that sets espresso apart from any other preparation method. Visual examination of the coffee in the cup reveals the elements of a high-quality blend and professional preparation: the colour of the crema (hue and intensity), consistency (compactness and quantity) and persistence (the amount of time it remains stable before breaking up).
These elements are taken into consideration before tasting, and they contribute to the final evaluation of the drink itself. While the colour of the crema is due to the fact that the sugars caramelise during roasting, its hue and intensity indicate the kinds of coffee that make up the blend, as well as the brewing parameters of the espresso machine.
For example, a good espresso made with a 100% Arabica blend will be characterised by a compact and persistent crema with an intense hazelnut colour and glossy reddish highlights.
Instead, blends with percentages of Robusta, which is less rich in oil, will have a darker and fluffier crema with duller highlights. Pale beige crema indicates under-extracted coffee, whereas dark tones and mahogany highlights are typical of an over-extracted espresso. The consistency and persistence are due to the emulsion of proteins, sugars with a high molecular weight, and other colloids during preparation.
Therefore, during the preparation phase, water at a temperature of 88-95°C (190-203°F) is forced through the previously pressed “disc” of coffee at a pressure of about 9 atm (128 psi). During the extraction phase, a whirling motion – generated by water and air, and involving the coffee’s essential oils – is produced inside the basket of the portafilter.
On a good Italian espresso, the crema should be about 3 mm (0.12″) thick, or equivalent to 10% of its volume (25-30 ml, or 0.8-1 fl oz).
The importance of the cup
The quality of an excellent espresso also depends on the object containing it: the cup.
In order to enhance the drink’s prominent traits, the cup should have a maximum capacity of 70 ml (2.5 fl oz) and have a tapered shape. But that’s not enough. Respecting these parameters and using a cup preheated to about 40°C (104°F) helps maintain the crema better, and this is the only element that can trap and concentrate the aromas. A good crema allows coffee enthusiasts to appreciate every aromatic nuance of the espresso as they stir it.
Instead, if the cups are cylindrical and very wide, this “breaks up” the crema. Today, the market offers an endless variety of cups. The leading coffee companies favour porcelain because of its greater value and brilliance, and its well-known resistance against temperature swings and chemicals (detergent). The white colour of the cup provides a matchless way of evaluating even the slightest nuances in the colour of the crema.
Attention: even the best espresso will taste good only if maintains the proper temperature. When the coffee spurts from the nozzles of the espresso machine, its temperature is about 80°C (176°F).
Since espresso is more unstable than coffee made using other methods, it must be drunk at a temperature of about 60°C (140°F) within a maximum of two minutes after it has gone into the cup, because its flavour and taste change substantially as time passes. Cooling not only breaks up the crema, but also accentuates bitterness and acidity.