How Does Machine Espresso Work?
The machine espresso makes use of precise pressure, as well as a filtering system that is awe-inspiring to make the coffee you love. What exactly is it that makes it work?
Espresso is made by pushing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.
The Group Head
The group head is the portafilter you insert when brewing espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure of the resulting extraction. There are a variety of types of group heads each with its unique advantages and drawbacks. Some are designed for stability of temperature while others are built to handle pre-infusion. Others are made to control the lever. There are even some that come with a range of features, like the E61, which is considered the most popular choice among baristas for its ability to offer multiple perks in one package.
As you can see in the above photo the group head is made up of numerous notches that you can put your portafilter, then twist it manually to secure it. A gasket made of rubber is placed inside the notches, which helps create a seal as you insert your portafilter. The notches on the head permit a precise positioning of the portafilter which is essential to ensure a consistent extraction.
Aside from allowing uk espresso machine to easily connect your portafilter, the group head is responsible for maintaining an even temperature. It does this by circulating hot water through the brew pan and around the portafilter, making sure that it is always at the right temperature for extraction. This is important because even a small difference in temperature can mean the difference between excellent and great espresso.
The Pump
In contrast to manual piston machines which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure needed to extract espresso. The pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger prior being shot through the ground coffee in the group head.
Pumps are generally cheaper and last longer than piston-driven machines. However, both types of machines are susceptible to degrading because of frequent use and poor cleaning. They also create mechanical complexity that can lead to an expensive price for even the most basic models.
Some espresso machines eliminate the pump completely and utilize steam pressure to make espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of the water to boiling which could lead to excessive extraction. The machines also need to constantly rebuild their pressure in between cups. This takes energy and time.
Many espresso machines make use of either a vibration or rotary pump. A vibration model employs a vibrating disk to generate pressure, whereas the rotary model pushes hot water through the ground at high speed. Both machines can make excellent espresso but rotary machines are more quiet, durable and less likely to break.
The Boiler
The boiler is the element that heats the water to the ideal temperature for extraction. The resultant steam then reaches the portafilter containing ground espresso beans and gets funnelled down into the cup. The steam generates enough pressure to push the grounds of coffee through. This results in a whipped-up the top of the espresso. This is one of the hallmarks of a great espresso.
There are three kinds of espresso machines, each with different types of pumps and the temperature of the brew. There are also different ways in which the brew can be controlled and the dimensions of the cup the maker can create.
The first espresso machines were steam types. The first espresso machines were steam-type machines. The coffee tasted bitter and burnt. The modern espresso machine was invented by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most well-known espresso maker is a semi-automatic machine with an electric pump. These are the things people think of when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans on your own The pump, however, regulates the flow of water and pressure. This is an excellent solution that combines human control with mechanised accuracy.
The Filter
Espresso machines typically have filters that separate the coffee grounds from the hot water. The filter is also a vital component of the machine's temp control, since it helps to prevent overheating.
A filter can also help with flavor as it allows for the beans to flower for a longer period of time. This helps the beans release their flavor and gives the chance for better extraction.
It is important to remember that even the best filter could result in a poor cup of coffee. The quality of the beans and the extraction process, are still very important.
This is where the magic happens. It's what makes espresso taste good. The grouphead, often called the brew head, is the place where the portafilter (the container you place the coffee grounds into) is placed when you're making espresso.
Steam-driven espresso machines use hot water that is heated in an airtight container to produce steam. The steam then pushes hot water into the grounds of coffee at high pressure. These machines are cheaper and easier to maintain than pumps-driven models. They are however limited in their ability to create the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, espresso machines driven by compressed air-pump have become increasingly popular. They use an air compressor to force the hot water through the grounds and are much more portable than electric steam-driven machines.