A Productive Rant About Machine Espresso

How Does Machine Espresso Work?

The machine espresso is made using precision pressure, and a filter technology that is mind-blowing to make the coffee you love. What exactly is it that makes it work?

travel espresso maker is created by forcing hot water at high pressure through finely-ground coffee and espresso maker. The process is similar to making drip coffee, but the key difference is in the pressure.

The Group Head

The group head is the portafilter that you put in when making espresso. It disperses water into the portafilter, and then regulates the pressure of the extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are designed for temperature stability while others are built to handle pre-infusion. Others are built to control the lever. There are also some that include a mix of features, such as the E61, which is the classic choice among many baristas because of its ability to offer multiple perks in a single package.

As you can see in the above photo, the group head has several notches where you place your portafilter before twisting it with your hands to secure it. A gasket made of rubber is placed in the notches to make a seal when you insert your portafilter. The notches allow for an exact placement of the portafilter. This is vital for a consistent extraction.

Apart from allowing you easily insert your portafilter, the group head is responsible to ensure that the temperature remains even. This is achieved by cycling hot water around the portafilter and through the brew-basket, making sure the temperature is always right for extraction. This is important, as even a small difference in temperature can mean the difference between excellent and great espresso.

The Pump

Contrary to manual piston machines that use a lever to pressurize water, rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure needed to extract espresso. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior to being pushed through the ground coffee inside the group head.

Pumps tend to be less expensive than piston-driven models, and they tend to last longer, however both types of machines may be damaged by excessive use and inadequate cleaning. Pumps are also more complex mechanically, which can raise the price of even the simple models.

Certain espresso machines do away with the pump completely and employ steam pressure to create espresso. This could lead to over-extraction since the boiler that produces steam also heats the water to boil. They also have to continually rebuild their pressure between cups. This takes energy and time.

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

The Boiler

The boiler is the component that heats water to an ideal temperature for extraction. The resulting steam is then transferred to the portafilter that contains the ground espresso coffee, and is then pumped into the cup. During this process the steam causes enough pressure to push the coffee grounds through. This results in a crema on the top of the espresso. This is a sign of a good espresso.

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

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

The most common espresso machine is a semiautomatic model with an electric pump. When people think of professional espresso machine machines, they envision these machines. Semi-automatic machines require you to grind and tamp the beans yourself however the pump controls the water flow and pressure. This is an excellent compromise between human control and mechanised reliability.

The Filter

Typically, espresso machines employ filters that separate the grounds of the coffee as they go through the hot water. The filter is also an essential component of the machine's temp control, since it stops overheating.

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

However, it is important to remember that even a great filter can produce a bad cup of coffee, as the quality of the beans and extraction is essential.

This is where the magic happens, and it's what makes an espresso really taste good. The grouphead (also called the brewhead) is where you put the portafilter, the thingy used to place the grounds of your coffee into when making espresso.

Steam-driven espresso machines use hot water that is heated in an airtight vessel to create steam. The steam then pushes hot water through the grounds of coffee under high pressure. These types of machines are generally less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing, as they operate with 1-1.5 bar of pressure. The ideal 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 electric steam-driven espresso machines.