10 Things That Your Family Teach You About Machine Espresso

How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and incredible filter technology to produce the coffee we love. How does it work exactly?

To make an espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee. However, the pressure is the primary difference.

The Head of the Group

The group head is the portafilter you place in the espresso maker when making it. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the resulting extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are specifically designed for stability in temperature, while others are specifically designed to handle pre-infusion. Some are designed to control the lever. Some have a combination, like the E61. This is a preferred choice for baristas because it offers multiple advantages in a single package.

As you can see in the image above the group head comes with numerous notches that you can place your portafilter before twisting it by hand to lock it in. There is also a gasket made from rubber that resides inside the notches and helps to create an airtight seal when you insert your portafilter into the machine. The notches on the head allow for a precise location of the portafilter which is essential for a consistent extraction.

The group head not only allows the portafilter to be inserted easily however, it also keeps a constant temperature. It does this by circulating hot water through the brew pan and around the portafilter, ensuring that it is always at the right temperature for extraction. This is important because just a few degrees could mean the difference between excellent and great espresso.

The Pump

Unlike manual piston machines, which use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure required for espresso extraction. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior to it is shot through the ground coffee in the group head.

Pumps are generally less expensive than piston-driven machines, and tend to last longer, however both types of machines may be damaged by excessive use and inadequate cleaning. They also create mechanical complexity that can lead to a high price tag on even the simplest models.

Some espresso machines can eliminate the pump completely and use steam pressure to brew espresso. This can lead to over-extraction as the boiler that produces steam also heats the water to boil. They also have to constantly rebuild their pressure between cups. This requires energy and time.

A large majority of espresso machines employ either a vibration or rotary pump. A vibration model uses a rotating disk to generate pressure, whereas the rotary model pushes hot water through the ground at a fast speed. Both models can make a great espresso, but Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the one that will heat the water to the right temperature for extraction. The resultant steam then reaches the portafilter which holds ground espresso beans and is then pumped into the cup. During this process, the steam creates pressure and pushes through the grounds of the coffee. This produces a layer of crema on top. This is the hallmark of a great espresso.

There are three kinds of espresso makers. They differ in the type of pump they use and how hot the brew is. There are different ways to control the brew and the size of the cup that can be produced by the machine.

The earliest espresso machines were steam types. They utilized one boiler to create both brew and steam, but the pressure they could produce was very low - just two bars of atmospheric pressure, at most. This resulted in the coffee tasting bitter and burnt. This is why the Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine black friday machine.

The most popular espresso maker is a semi-automatic machine that has an electric pump. When people think of espresso machines, they think of these machines. 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 quality.

The Filter

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

It also aids in flavor, since a filter can allow for a longer bloom time. This lets the beans let their nuances out, and improves extraction.

It is important to keep in mind that even the most efficient filter can produce a bad cup of coffee machines espresso. The quality of the beans as well as the extraction, are still crucial.

This is where the magic happens, it's the thing that makes espresso machine with grinder taste good. The grouphead, often called the brewhead, is where the portafilter (the thing you put the coffee grounds into) sits when you're making espresso.

Steam-driven espresso machines use hot water heated in an airtight container to produce steam. The steam then pushes hot water through the grounds of coffee at high pressure. These machines are less expensive and are easier for the user to maintain than pumps-driven models. However, they are limited in their ability to produce the perfect brewing conditions as they only operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.

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