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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the perfect cup of coffee. How does it work exactly?

To make espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However, the pressure is the major espresso makers difference.

The Group Head

As the name implies, the group head is where you insert your portafilter when making espresso. It distributes water into the portafilter, and controls the pressure of the extraction. There are a variety of group heads each with their own advantages and drawbacks. Some focus on temperature stability, others on pre-infusion features, and others are designed to control the lever. Some include a mix of features, such as the E61 one, which is the classic choice among many baristas for its ability to offer multiple perks in a single package.

As you can see in the image above The group head features many notches in which you can place your portafilter and then twist it manually to lock it in. A gasket made of rubber is placed inside the notches to help create a seal when you insert your portafilter. The notches on the head allow for an exact location of the portafilter which is vital to ensure an even extraction.

In addition to allowing you to easily insert your portafilter, the group head is also responsible to maintain an even temperature. This is accomplished by cycling hot water around the portafilter, and through the brew-basket, ensuring the temperature is always right to extract the coffee. It is important to note that even a slight difference can make the difference between a good and great espresso.

The Pump

In contrast to manual piston machines which rely on a lever to pressurize water, rotating espresso machines rely upon motorized pumps to deliver the nine atmospheric bars of pressure needed for espresso extraction. This pressure is generated by pumping water through a heat-exchanger and then through the best ground coffee for espresso machine coffee.

Pumps are generally more affordable and last longer than piston-driven machines. However, both types of machines may degrade because of excessive use and insufficient cleaning. Pumps are also more complicated mechanically, which can increase the cost of even simplest models.

Some espresso machines do away with the pump entirely and employ steam pressure to create espresso. The drawback is that the same boiler that produces steam also raises the temperature of the water to boiling which can cause excessive extraction. Additionally these machines typically have to rebuild their pressure between cups, which takes time and espresso makers energy.

Many espresso machines utilize a vibration or rotary pump, which is a vibration model using a rotating disc to generate the pressure, and an rotary model that pushes hot water through the grounds at high speed. Both machines can produce excellent espresso, but rotary machines are more quiet, durable and less likely to break down.

The Boiler

The boiler is what makes the water warm to the right temperature for extraction. The steam produced gets to the portafilter which is the container that holds the espresso coffee grounds. It is then poured into the cup. The steam is able to create enough pressure to push the coffee grounds through. This results in a layer crema on top. This is one of the hallmarks of a good espresso coffee machine uk.

There are three types of espresso makers, which differ in the kind of pump they use and the degree of heat that the brew is. There are a variety of ways in which the brew could be controlled, as well as the dimensions of the cup the machine is capable of making.

The earliest espresso machines were steam types. They utilized one boiler to make steam and brew, but the pressure they could produce was very low - just two bars of atmospheric pressure maximum. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was invented by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso maker is a semi-automatic device that has an electric pump. This is what people envision when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans yourself while the pump controls the water flow and pressure. This is a great compromise between the human touch and the mechanized consistency.

The Filter

Espresso machines typically have a filter that separates the grounds of the coffee from the hot water. The filter is also an important part of the temperature control system as it prevents the machine from overheating.

It also improves flavor, since a filter lets you enjoy a longer bloom phase. This allows the beans to let their nuances out, and allows for better extraction.

It is important to remember that even the finest filter could result in a poor cup of coffee. The quality of the beans, and the extraction process are still crucial.

It's in this area that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead (also called the brewhead) is where you put the portafilter, the device used to place the coffee grounds into, when making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight vessel to create steam. The steam then pushes hot water into the coffee grounds under high pressure. These types of machines tend to be less expensive and simpler to maintain than pump-driven models. However, they are not as efficient in their ability to produce the perfect brewing conditions because they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.

In recent years, espresso machines driven by a compressed air pump have become increasingly popular. They use an air compressor to push hot water through the grounds, and are far more portable than electric steam-driven machines.