5 Killer Qora's Answers To Machine Espresso

How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the perfect cup of coffee. What exactly is it?

Espresso is made by pushing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee. However, the pressure is the primary difference.

The Group Head

The name implies the group head is the place you place your portafilter while brewing espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the resulting extraction. There are many different types of group heads each with distinct advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion capabilities, and still others are designed to control the lever. There are even some that have a combination of features, like the E61, which is considered the most popular choice among baristas due to its ability to offer multiple perks in one package.

As you can see in the above photo the group head comes with many notches in which you can place your portafilter and then twist it manually to lock it in. A gasket made of rubber is positioned inside the notches, which helps create a seal while you insert your portafilter. The notches permit an exact placement of the portafilter. This is essential for an efficient extraction.

The group head does not just allow you to put in your portafilter easily however it also keeps a constant temperature. This is accomplished by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is constant to extract the coffee. This is important because even a few degrees can mean the difference between good and excellent espresso.

The Pump

In contrast to manual piston machines which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure required for espresso extraction. The pressure is created by pumping water through a heat exchanger and then through the ground coffee.

Pumps tend to be cheaper than piston-driven machines, and tend to last longer, although both types of machines could be damaged by excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which could increase the cost of even simple models.

Certain espresso machines can eliminate the pump completely and use steam pressure to brew espresso. This can result in over-extraction because the boiler that makes steam also warms the water to boil. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

Many espresso machine sale machines utilize either a rotary or vibration pump, with a vibration model using a rotating disc to generate the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both machines can produce excellent espresso however rotary machines tend to be more stable, quieter and less likely to break down.

The Boiler

The boiler will heat the water to the perfect temperature to extract. The steam created gets to the portafilter which holds the espresso grounds. It is then funneled into the cup. The steam is able to create enough pressure to push the grounds of coffee through. This results in a layer of crema that is then poured over. This is a hallmark of a good espresso.

There are three distinct types of espresso machines, each having different pumps and the temperature of the brew. There are many ways to control the strength of the brew and the size of the cup that can be produced by the machine.

The earliest espresso machines were steam types. The earliest espresso machine with frother machines were steam-type machines. This led to the coffee and espresso maker tasting bitter and burnt. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most commonly used espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the water flow and pressure. This is a great compromise between the human touch and the mechanised quality.

The Filter

Typically, espresso machines use filters to separate the grounds of coffee when they pass through the hot water. The filter is also a vital component of the machine's temperature control, as it helps prevent overheating.

A filter can also help with flavor as it allows for a longer flowering phase. This lets the beans release their flavor and allows for a better extraction.

However, it is important to remember that even a top filter can result in a poor cup of coffee, because the quality of the beans and extraction are essential.

It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead, sometimes called the brew head, is where the portafilter (the device you put the ground coffee into) sits when you're making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to create steam. The steam then pushes hot water into the grounds of coffee under high pressure. These kinds of machines are usually less expensive and simpler to maintain than pumps-driven models. They are however limited to create the perfect conditions for brewing as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent years, compressed air-driven espresso machines have been gaining popularity. They make use of an air compressor to force hot water through the ground, and are more mobile than steam-driven electric espresso machines.