The perfect espresso

Everything you need to know for a perfect espresso

Today we are celebrating Espresso Day. An event day that we would like to use to tell you everything you need to know to make the perfect espresso.

First of all, a few basics about the flavour profile and taste sensation

The flavour profile is the combination of the taste sensation on the tongue (taste buds), the perception of aroma (ortho- and retronasal) and the perception of mouthfeel (texture, body, balance = tactile perception).

The optimal flavour profile consists of a balanced proportion of aromas/fragrances, flavour components - especially sought-after acids and bitter substances - and a pleasant mouthfeel, which together enable a balanced enjoyment experience.

In order to achieve a balanced flavour profile in the cup, a carefully adjusted and executed brewing process is important in addition to good water and coffee quality.

The brewing process in a coffee machine is influenced by the following main criteria: pump pressure, brewing temperature, brewing ration, contact pressure and grind.

Visually, a perfect espresso presents itself with a golden or hazelnut-brown, fine-pored crema with a dense consistency.

Step 1: Defining flavour

We perceive five flavours on the tongue: sweet, sour, bitter, salty and umami.

When describing flavours, it helps to ask which flavour components are perceived most distinctly on the tongue. If there is a tingling sensation mainly around the tip of the tongue, on the sides and even under the tongue, the acidity is well perceived. If you only feel something when you swallow the coffee, perhaps a slight scratchiness or a slightly dry sensation, it may be the bitterness that is being perceived.

Sweet, sour, salty, bitter and umami are not only perceived in the areas shaded in colour in the diagram. They do, however, help to identify and sense where the respective flavour is perceived as strongest in the individual flavour identification.

The flavour definition alone does not provide a balanced picture of the coffee beverage. In addition to taste, the complete, optimal flavour profile also consists of smell/aroma and mouthfeel.

Odour/aroma
The nose (ortho- and retronasal) perceives the various odours/aromas that give the coffee its individuality. Coffee aromas offer a countless variety of smells: from floral to fruity, berry to tart, depending on the coffee origin (enzymatic aromas), to various roasted aromas such as chocolaty, nutty to spicy and even charcoal/smoky, depending on the roast start, degree of roast and/or coffee variety.

Mouthfeel
Another important point is the perception of the mouthfeel, the so-called haptic sensory impression. Above all, the body and balance are described. The body describes the perception of the fullness and viscosity of a beverage: creamy, syrupy, velvety or rather light and watery. The balance reflects whether the coffee is balanced and whether the flavour, aroma and mouthfeel harmonise with each other.

Step 2: Extraction

Extraction occurs when hot water is forced through the pressed coffee grounds under pressure. This dissolves the coffee's own oil and fat substances and forms a firm, fine-pored, creamy layer, the crema. As mentioned at the beginning, in addition to the brewing and contact pressure, the degree of grinding, the corresponding brewing time, the brew ratio and the brewing temperature also influence the result in the cup and therefore the quality of the beverage.

We differentiate between the preparation time (including grinding), the run-down time (start of the pump to the outlet) and the extraction time (contact time of water and ground coffee).

^{The following illustration shows the tendency of various ingredients/substances to dissolve during extraction in a fully automatic coffee machine (extraction time 12 to 15 seconds for a single espresso or plus/minus 25 seconds for a double beverage).}

Step 3: Choosing the coffee

If you want to achieve the best coffee flavour, there is no getting around a good choice of coffee.

With an espresso blend (espresso: short contact time with water and dark roast), the roast flavours are particularly emphasised. This means a strong flavour, a long and pleasant finish with a creamy, balanced mouthfeel. You can recognise dark roasting by the following three points:

Tends to have a higher bitter content.flavours: more smoky or tobacco-like depending on the variety, origin and processing.
Very suitable for espressos. The bitter substances and body harmonise very well when prepared with little water.
A very dark roast gives the espresso a smoky flavour and, in combination with milk, even develops caramel-like aromas.

Coffee freshness

As soon as coffee comes into contact with oxygen and heat, it begins to lose its flavour. The coffee beans should therefore always be stored in their original packaging in an airtight, dark and cool place for as long as possible.

ATTENTION: In addition, the coffee machine's bean container should only be filled with the daily requirement. This is the only way to minimise the escape of aromas.

The roasting date or, in other words, the age of the roasted coffee also influences the quality in the cup. Coffee needs a certain resting time after roasting, the time for so-called "outgassing". Freshly roasted coffee beans release large quantities of carbon dioxide (CO2) even days later. By using a flavour valve in the packaging, the freshly roasted beans can be filled and packaged directly, with little or no loss of flavour. The valve allows the gas to escape in the event of overpressure without allowing oxygen to enter the packaging. Once the coffee has degassed, there is very little carbon dioxide left in the beans. The coffee is now "ready to drink". The flavour nuances have developed sufficiently and are much more pronounced than immediately after roasting. This process takes around two to three weeks for dark roasts, but slightly less time for lighter roasts.

Step 4: Water quality

Depending on the brewing method, coffee consists of up to 99 per cent water. This is therefore a very important component for a pleasant coffee flavour.

The water quality influences the coffee extraction and therefore also the coffee flavour through the following factors:

The hardness of the water (total hardness and alkalinity), which is given in French degrees of hardness [°fH] or in German degrees of hardness [°dH].
The pH value of the water (acidic or basic/alkaline), which is measured on a scale from 0 to 14.

Ideal water for coffee should have a balanced content of minerals such as calcium and magnesium as well as sufficient total hardness and alkalinity.
Ideal water for coffee should be as follows:
Odourless, clear and hygienic
No disturbing coarse and fine particles
A total hardness that is higher than the alkalinity
Total hardness 3-6 °dH (50-108 ppm CaCO3)
Alkalinity 2-4 °dH (40-75 ppm CaCO3)
A pH value between 6.5 and 8.0
An electrical conductivity (in [μS/cm] at 20 °C) of less than 50 times the alkalinity in [°dH]

You can find out more about water, the effects of different types of water on coffee quality and the devices here.

Step 5: Instructions for a perfect espresso

Depending on the type of coffee, an espresso with 9.5 g of ground coffee and 35 ml of water should achieve a brewing time of 12 to 15 seconds if two grinders are available. A lungo/café crème with 9.5 g of ground coffee and 110 ml of water should achieve a brewing time of 18 to 22 seconds.

The perfect setting

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