A Good Rant About Machine Espresso

How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and mind-blowing filter technology to make the perfect cup of coffee. What exactly is it?

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

The Group Head

The name implies, the group head is where you put your portafilter in when making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the resulting extraction. There are many different types of group heads each with their own advantages and disadvantages. Some are designed to provide stability of temperature while others are built to handle pre-infusion. Others are made to control the lever. Some are a combination, like the E61. This is a popular choice among baristas due to the fact that it has multiple advantages in a single package.

As you can see in the image above the group head is equipped with several notches. It is possible to place your portafilter in these notches and then turn the head around to secure it. There is also a gasket made from rubber in the notches, which helps create a seal when you insert your portafilter into the machine. The notches on the head permit a precise positioning of the portafilter which is necessary to ensure an efficient extraction.

The group head does not just allow you to insert your portafilter easily however, it also keeps the temperature at a constant level. It does this by cycling hot water through the brew basket and around the portafilter, ensuring that it is always at the correct temperature for extraction. This is crucial, since even a small difference in temperature can be the difference between a good and great espresso.

The Pump

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

Pumps tend to be more affordable and last longer than piston-driven machines. However, both kinds of machines can degrade because of excessive use and poor cleaning. Pumps are also more complicated mechanically, which can raise the price of even the most basic models.

Certain espresso machines do away with the pump entirely and make use of steam pressure to make espresso. The drawback is that the boiler that produces steam also increases the temperature of water to boiling which could lead to over-extraction. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

A large majority of espresso machines employ the rotary or vibration pump. A vibration model uses a vibrating disk to generate pressure, whereas a Rotary model pushes hot coffee through the ground at a fast speed. Both machines can make great espresso but rotary machines are more stable, quieter and less likely to fail.

The Boiler

The boiler is the element that heats the water to the ideal temperature for extraction. The steam that is created gets to the portafilter which is a container for espresso grounds. It is then funneled into the cup. The steam is able to create enough pressure to push the grounds of coffee through. This results in a whipped-up top of the espresso. This is one of the main characteristics of a good espresso.

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

The first espresso machines were steam-types. They utilized only one boiler to make steam and brew, however, the pressure they could create was minimal - two bars of atmospheric pressure, at most. The coffee tasted bitter and burned. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso maker is a semi-automatic device with an electric pump. This is what people envision when they think of an espresso maker. Semi-automatic machines require you to grind and tamp your beans yourself however the pump controls the water flow and pressure. This is a fantastic compromise between human control and mechanised accuracy.

The Filter

Espresso machines usually have filters that separate the grounds of coffee from hot water. The filter is also an essential element of the temperature control system, because it stops the machine from overheating.

It also enhances flavor, as a filter allows for a longer bloom time. This allows the beans to release their flavor and also allows for better extraction.

It is important to remember that even the best filter can result in a bad cup of coffee. The quality of the beans, and the extraction process, remain vital.

This is where the magic happens, and it's what makes an mini espresso maker really taste great. The grouphead, sometimes called the brew head, is the place where the portafilter (the thingy you put the ground coffee in) sits when you're making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight container to create steam, which is then pushed through the grounds with high end espresso machine pressure. These types of machines are generally cheaper and easier to maintain than pump-driven models. They are however limited in their ability for creating the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The perfect shot requires 9 bar espresso machine-10 bars.

In recent years, Espresso machine With milk frother (worldaid.eu.org) machines driven by compressed air-pump are becoming increasingly popular. They use an air compressor to force hot water into the ground and are much more mobile than electric steam-driven espresso machines.