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How Does Machine Espresso Work?

The machine espresso makes use of precise pressure and filtering technology that is amazing to create the coffee you love. How does it work exactly?

To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However it is the pressure that makes the main difference.

The Head of the Group

As the name suggests the group head is where you place your portafilter while brewing espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the resulting extraction. There are several different types of group heads each with its unique advantages and drawbacks. Some are designed to provide stability in temperature, while others are built to handle pre-infusion. Others are built to control the lever. Some are a combination, like the E61. This is a favorite among baristas because it offers multiple benefits in one package.

As you can see in the photo above the group head is fitted with several notches. You place your portafilter in these notches, then turn the head around to secure it. A gasket made of rubber is placed inside the notches, which helps create a seal when you insert your portafilter. The notches on the head permit an exact placement of the portafilter, which is necessary to ensure a consistent extraction.

Aside from allowing you to effortlessly 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, ensuring that the temperature is constant for extraction. It is important to remember that even a slight deviation can make the difference between a good and great espresso.

The Pump

The motorized pumps that are used in rotary espresso machines supply the nine atmospheric bar pressure needed for espresso extraction. This is different from manually operated piston machines that employ a lever. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior to being shot 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 could increase prices of even simple models.

Some espresso machines eliminate the pump completely and utilize steam pressure to make espresso. This can result in over-extraction because the boiler that makes steam also heats the water to boil. The machines also need to constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines employ a vibration or rotary pump, with a vibrating model using a rotating disc that generates the pressure and an rotary model that pushes hot water through the grounds under high speed. Both machines can make excellent Discount Espresso Machines, however rotary machines are more stable, quieter and less likely to fail.

The Boiler

The boiler is the part that heats water to an optimal temperature to extract. The resultant steam then reaches the portafilter, which contains the ground espresso and is then funneled down into the cup. During this process the steam generates enough pressure to push the grounds of the coffee through. This results in a crema on the top of the espresso. This is a sign of a great espresso machine with frother.

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

The earliest retro espresso maker machines were steam type. They had one boiler to make both brew and steam, but the pressure they could generate was low - only two bars of atmospheric pressure maximum. This resulted in the coffee tasting burnt and bitter. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most commonly used espresso maker is a semiautomatic machine that has an electric pump. These are what people imagine when they think of an espresso machine. With a semi-automatic espresso machine, you must grind the beans and then tamp them by hand. However, the pump regulates the flow of water and pressure. This is a perfect combination of human control and mechanized consistency.

The Filter

Typically, espresso machines have filters to separate the grounds of coffee as they move through the hot water. The filter is also a vital part of the temperature control system, because it stops the machine from overheating.

A filter also helps with flavor since it allows for the beans to flower for a longer period of time. This allows beans to release their flavors and provides the chance for better extraction.

However it is crucial to keep in mind that even a top filter can produce a bad cup of coffee as the quality of the beans and extraction is crucial.

It's in this area that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead (also known as the brewhead) is where you place the portafilter, the thingy that you use to put the coffee grounds in, when making espresso.

Steam-driven espresso machines use hot water heated in an airtight container to create steam. The steam then pushes hot water into the coffee grounds under high pressure. These kinds of machines are usually cheaper and easier to maintain than pumps-driven models. They are however limited for creating the ideal 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-pump-driven espresso machines have been gaining popularity. They use an air compressor to push hot water across the ground and are much more mobile than steam-driven electric espresso machines.