9 Things Your Parents Teach You About Machine Espresso

How Does Machine Espresso Work?

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

Espresso is created by forcing hot water under pressure through finely ground coffee. The process is similar to making drip coffee, but the difference is in the pressure.

The Head of the Group

The group head is the portafilter that you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter and controlling the pressure that results from the extraction. There are a variety of types of group head each with its own advantages and disadvantages. Some are designed for stability in temperature, while others are built to handle pre-infusion. Others are built to control the lever. There are some that come with a range of features, such as the E61, which is the classic choice among many baristas due to its capacity to offer multiple benefits in a single package.

As you can see in the image above the group head is made up of several notches to place your portafilter and twist it manually to secure it. A gasket made of rubber is placed in the notches to create a seal when you insert your portafilter. The notches on the head permit a precise positioning of the portafilter which is vital for an even extraction.

Apart from allowing you easily insert your portafilter, the group head is responsible to ensure that the temperature remains even. This is done by cycling hot water around the portafilter, and through the brew-basket to ensure that the temperature is constant for extraction. This is important because just a few degrees could make the difference between a good and excellent espresso.

The Pump

The motorized pumps used in best espresso machine under 500 machines rotary provide nine atmospheric bar pressure required for retro espresso machine extraction. This is different from manually operated piston machines that employ levers. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically cheaper and last longer than piston-driven machines. However, both types of machines are susceptible bean to cup espresso machines degrading due to excessive use and insufficient cleaning. Pumps are also more complex mechanically, which can raise prices of even most basic models.

Certain espresso machines can eliminate the pump completely and instead employ steam pressure to create espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. These machines also have to continually rebuild their pressure between cups. This takes energy and time.

Many espresso machines use a rotary or vibration pump. A vibration model makes use of a vibrating disk to generate pressure, while a circular model pushes hot liquid through the ground at a rapid speed. Both types of machines can produce an excellent espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component that heats water to the optimal temperature to extract. The steam created gets to the portafilter which is a container for espresso grounds. It is then funneled into the cup. In this process, the steam causes pressure to push through the grounds of the coffee. This results in a whipped-up top of the espresso. This is one of the hallmarks of a good espresso.

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

The earliest espresso machines were steam type. The first espresso machines were steam-type machines. This resulted in the coffee tasting bitter and burnt. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso machine is a semiautomatic one with an electric pump. These are what people imagine when they think of an espresso maker. Semi-automatic machines require you to grind and tamp your beans yourself while the pump controls the flow of water and pressure. This is a perfect solution that combines human control with mechanized consistency.

The Filter

Espresso machines usually have filters that separate the grounds of the coffee from hot water. The filter is also an essential part of the temperature control system as it prevents the machine from overheating.

A filter also helps with flavor since it allows for an extended flowering time. This allows the beans to release their flavor and allows for better extraction.

However, it is important to remember that even a good filter can result in a poor cup of coffee, since the quality of the beans and extraction is still vital.

This is where the magic happens. It's what makes espresso taste good. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy used to place the coffee grounds into, while making espresso.

In a steam-driven espresso machine hot water is heated in an airtight container to produce steam, which is then pushed through the grounds at a high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. They are however limited to create the perfect conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

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