How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to create the coffee we love. What exactly is it that makes it work?
In order to make espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the major difference.
The Head of the Group
The name implies, the group head is where you insert your portafilter when brewing espresso. It disperses the water into the portafilter and regulates the pressure during the extraction. There are a variety of group heads each with their own advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion features, and others are designed to control the lever. There are even some that include a mix of features, such as the E61, which is considered the standard choice for many baristas because of its ability to offer multiple perks in a single package.
As you can see in the photo above, the group head has several notches where you place your portafilter before twisting it by hand to lock it in. A gasket of rubber is situated within the notches to create a seal while you insert your portafilter. The notches on the head permit an exact placement of the portafilter,
Machine Espresso which is necessary to ensure a consistent extraction.
Apart from allowing you easily place your portafilter in, the group head is also responsible for maintaining a consistent temperature. It does this by circulating hot water through the brew basket and around the portafilter to ensure that it's always at the right temperature for extraction. It is important to realize that even a slight differences can make the distinction between a good and excellent espresso.
The Pump
The motorized pumps that are used in espresso machines rotary provide nine atmospheric bar pressure needed for espresso extraction. This is different from manual piston machines which use levers. The pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger before being pumped through the ground
coffee and espresso maker inside the group head.
Pumps are generally less expensive than piston-driven machines, and they tend to last longer, however both types of machines could 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 remove the pump completely and instead utilize steam pressure to make espresso. This can lead to over-extraction as the boiler that produces steam also warms the water to boil. These machines also have to continually rebuild their pressure between cups. This requires energy and time.
Many espresso machines use an rotary or a vibration pump. A vibration model utilizes an oscillating disk to create pressure, while a rotary model pushes hot water through the ground at a rapid speed. Both types of machines can make a great espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the part that heats water to an ideal temperature to extract. The resultant steam then reaches the portafilter containing the ground espresso coffee, and gets funnelled down into the cup. During this process the steam is able to create enough pressure to push the grounds of coffee through. This produces a layer of crema on top. This is a hallmark of a great espresso.
There are three types of espresso makers. They differ in the type of pump they employ and how hot the coffee is. There are different ways to control the amount of brew, as well as the size of the cup that can be made by the machine.
The first espresso machines were steam type. The first espresso machines were steam types. The coffee tasted bitter and burned. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most common espresso maker is a semi-automatic machine with an electric pump. These are the things people think of when they think of an
best budget espresso machine machine. Semi-automatic machines require you to grind and tamp the beans yourself however the pump controls the water flow and pressure. This is a great compromise between the human touch and mechanized accuracy.
The Filter
Typically, espresso machines have filters to separate the grounds of coffee when they pass through the hot water. The filter is also a vital part of the machine's temperature control, as it prevents overheating.
It also helps with flavor, since a filter lets you enjoy a longer bloom phase. This allows the beans to let their nuances out and provides an opportunity for a better extraction.
However it is crucial to remember that even a good filter could result in a bad cup of coffee, since the quality of the beans and extraction is important.
This is where the magic happens. It's what makes an espresso really taste good. The grouphead, often referred to as the brew head, is the place where the portafilter (the thing you put the ground coffee in) sits when you're making espresso.
Steam-driven espresso machines use hot water that is heated inside an airtight container to produce steam. The steam then pushes hot water through coffee grounds under high pressure. These kinds of machines tend to be less expensive and simpler to maintain than pumps-driven models. However, they are limited in their ability to provide the perfect brewing conditions because they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.
In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They use an air compressor to force hot water through the ground. They are also more mobile than electric steam-driven espresso machines.