The espresso machine was patented in 1884 as a system for making coffee and presented at the General Exposition in Turin’s Parco del Valentino. Angelo Moriondo developed it for use in the café of the Hotel Ligure on Piazza Carlo Felice, opposite Porta Nuova train station.
Since then, all sorts of research, alterations and improvements have been carried out in an effort to enhance its functions and – above all – to perfect the end product: our beloved espresso.
But how does a professional espresso machine actually work?
Essentially, a professional espresso machine forces pressurized water through a chamber containing ground coffee. The water flows through a filter that ensures only the liquid part passes through, then the espresso appears in the cup below.
Those are the basics, but why don’t we look at it all in a little more detail? After the barista presses the button to start the dispensing process, in just a few seconds the espresso machine takes the water to a temperature of approximately 90°C and a pressure of 9 atm. This means that a whole host of aromas and flavours can be extracted from just a few grams of ground coffee, while also ensuring that the caffeine content is not too high.
Let’s take a look at the different stages.
- First of all, an electric pump takes water from the mains supply, pressurizes it and forces it through a heat exchanger, which increases its temperature. The water then goes to the group head, where it comes into contact with the ground coffee.
- The ground coffee must be dosed and tamped in the porta-filter before the latter is attached to the group head. This is where the crucial pre-infusion stage takes place.
- Pre-infusion is only possible with professional espresso machines. It extends the contact time between the water and the ground coffee, thus forcing the carbon dioxide out of the latter and making it easier for the water to pass through it. It is technically a form of percolation that sees water going through the cells in the ground coffee and freeing all of its aroma, flavour and other sensory properties.
It is the only way to preserve all of the purity of the coffee and also the only way to produce the trademark crema that everyone expects from superior espresso.
We can look at things in even more detail by examining the “mechanical” parts in an espresso machine. There is one for each of its functions.
The main ones are described below.
Found between the mains supply and the espresso machine, the water softener has a key role. In order to make good espresso, the water must be as pure as possible, with no smell, flavour or colour. In addition, the calcium and magnesium contents must be very low. The water softener contains a filter that reduces the hardness of the water and takes care of all of this.
The boiler heats the water to the right temperature. Depending on the type of machine, the heat source may either be an electric element or a gas burner.
The heat exchanger is the system inside the boiler that is surrounded by hot water and steam. It takes the water to 90°C, which is the required temperature for extraction.
The group head is the part of the machine where the porta-filter is attached. It contains a thermosiphoning system for water recirculation that constantly keeps the temperature at the same level, because a fall in it could affect the quality of the end product.
The electric pump has the essential role of increasing the water pressure. This is because the pressure of water when it leaves the mains supply is between 1 and 3 atmospheres, but it needs to be at 8 or 9 atmospheres to force its way through the puck of ground coffee.
Rounding things off in this section are the water level controller that keeps the water in the boiler at a constant temperature and the solenoid valves that control the flow of water and steam. In the final section of the stretch leading to dispensing is a shower with a round steel screen that ensures the hot, pressurized water is distributed evenly through the coffee.
Below is the porta-filter, which contains the actual filter and is separated from the group head by a silicon rubber gasket that forms a tight seal. The porta-filter has a thermally insulated handle and spouts underneath, where the coffee emerges.
As well as having all the right equipment, it’s essential to keep it in good order by carrying out regular maintenance on the machine and cleaning it frequently, especially the coffee grinder and doser, the porta-filter, the filter and the steam wand.
Now that you’ve learned all about how the different parts of a professional espresso machine work, all you need is the right blend, which is where Manuel Caffè comes in. Its professional, aromatic and irresistible products are bursting with the undeniable appeal of a company that’s capable of squeezing huge amounts of quality into a tiny cup.
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