How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and amazing filter technology to make the perfect cup of coffee. But how exactly does it work?

To make espresso machine small hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, but the major difference is in the pressure.

The Group Head

As the name implies the group head is the place you insert your portafilter when brewing espresso. It is responsible for dispersing the water into the portafilter before controlling the pressure that results from the extraction. There are many different kinds of group heads each with its own advantages and disadvantages. Some are designed for stability in temperature, while others are designed to handle pre-infusion. Others are made to control the lever. Some are a combination, like the E61. This is a favorite among baristas since it provides multiple benefits in one package.

As you can see in the picture above the head of the group is fitted with a variety of notches. You place your portafilter inside these notches, and then turn the head around to secure it. There is also a rubber gasket that resides inside the notches and helps to create a seal when you insert your portafilter into the machine. The notches permit an exact placement of the portafilter. This is vital for an efficient extraction.

The group head does not just allow you to put in your portafilter easily, but it also maintains the temperature at a constant level. It does this by circulating hot water through the brew basket and around the portafilter, ensuring that it is always at the correct temperature for extraction. This is important because just a few degrees could make the difference between good and excellent espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever to pressurize water, the rotary espresso machines use motorized pumps that provide the nine atmospheric bars of pressure needed to extract espresso. The pressure is built by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be cheaper than piston-driven machines, and they tend to last longer. However, both types of machine can be damaged by excessive use and inadequate cleaning. Pumps are also more complicated mechanically, and can add to prices of even simplest models.

Certain espresso machines can eliminate 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 water to the point of boiling and can result in excessive extraction. In addition these machines typically have to rebuild their pressure between cups, which requires time and energy.

Many espresso machines employ an rotary or vibrating pump, which has a vibration model that uses a vibrating disc to create the pressure, and an rotary model that pushes hot water through the grounds at high speed. Both types of machine can produce an excellent espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the part that heats water to an optimal temperature for extraction. The resultant steam then reaches the portafilter containing the ground espresso coffee and gets funnelled down into the cup. The steam causes pressure to push through the grounds of the coffee. This creates a crema on top of the espresso. This is a hallmark of a great espresso.

There are three types of espresso makers, which differ in the type of pump they use and the degree of heat that the coffee is. There are a variety of ways to control the brew and the size of the cup that can be produced by the machine.

The earliest best budget espresso machine machines were steam-based. The first home espresso machine machines were steam-type machines. This led to the coffee tasting burnt and bitter. The modern barista espresso coffee machine machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso maker is a semi-automatic device that has an electric pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp the beans by yourself The pump, however, regulates the water flow and pressure. This is a great compromise between the human touch and mechanized quality.

The Filter

Typically, espresso machines have filters to separate the coffee grounds as they pass through the hot water. The filter is also an essential element of the machine's temperature control, as it prevents overheating.

It also enhances flavor, as a filter allows for a more prolonged bloom time. This allows the beans to let their nuances out and provides an opportunity for a better extraction.

It is important to keep in mind that even the most efficient filter could result in a poor cup of coffee. The quality of the beans and the extraction process are still very important.

It's in this area that the magic happens. This is the reason why espresso tastes so good. The grouphead, also referred to as the brewhead, is where the portafilter (the device you put the coffee grounds into) is located when you're making espresso.

Steam-driven espresso machines use hot water that is heated in an airtight container to produce steam. The steam then pushes hot water through grounds of the coffee under pressure. These types of machines are generally less expensive and simpler to maintain than pumps-driven models. However, they are not as efficient in their ability to create the perfect conditions for brewing, as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.

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