How Does Machine Espresso Work?
The machine espresso uses precision pressure, and filtering technology that is amazing to create the coffee you love. What exactly is it that makes it work?
Espresso is made by forcing hot water 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 group head is the portafilter that you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter before controlling the pressure of the resulting extraction. There are many different types of group heads each with their own advantages and drawbacks. 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, such as the E61. This is a preferred choice for baristas since it provides multiple advantages in one package.
As you can see in the above photo The group head features several notches where you place your portafilter before twisting it by hand to secure it. There is also a gasket of rubber that is a part of the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches allow for precise placement of your portafilter. This is crucial for an accurate extraction.
In addition to allowing you effortlessly insert your portafilter the group head is also responsible to maintain an even temperature. It does this by cycling hot water through the brew basket, and around the portafilter to ensure that it is always at the right temperature for extraction. This is crucial, since even a small difference in temperature can mean the difference between excellent and great espresso.
The Pump
Motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure needed to extract espresso. 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 prior to being pumped through the ground coffee in the group head.
Pumps are typically less expensive than piston-driven machines, and they tend to last longer, but both types of machines could be damaged by excessive use and inadequate cleaning. They also increase the complexity of mechanical systems that can lead to costly prices for even the most basic models.
Some espresso machines employ steam pressure instead of a pump to make espresso. This could lead to over-extraction since the boiler that produces steam also heats the water to boil. They also have to constantly rebuild their pressure between cups. This takes energy and time.
Many espresso machines use a rotary or vibration pump. A vibration model utilizes a rotating disk to generate pressure, whereas the circular model pushes hot liquid through the ground at a rapid speed. coffeee.uk can make great espresso but rotary machines are more quiet, durable and less likely to break down.
The Boiler
The boiler heats the water to the right temperature to extract. The steam that is produced is then directed to the portafilter, which contains the espresso coffee grounds. It is then poured into the cup. During this process the steam causes enough pressure to push the grounds of the coffee through. This results in a whipped-up the top of the espresso. This is one of the hallmarks of a good espresso.
There are three distinct types of espresso machines, each having different pumps and the temperature of the brew. There are various ways to control the brew and the size of cup that can be produced by the machine.
The first espresso machines were steam-type. The earliest espresso machines were steam types. The coffee tasted bitter and burnt. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most common espresso maker is a semi-automatic one that has an electric pump. These are what people imagine when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the flow of water and pressure. This is a great combination of human control and mechanised reliability.
The Filter
Espresso machines usually have filters that separate the grounds of coffee from hot water. The filter is also a vital part of the temperature control system, as it prevents the machine from overheating.
It also improves flavor, since a filter can allow for a longer bloom time. This allows beans to release their nuances 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 remain vital.
It's in this area that the magic happens. This is what makes espresso taste so delicious. The grouphead, sometimes referred to as the brewhead, is where the portafilter (the device you put the ground coffee in) is placed when you're making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to create steam. The steam then pushes hot water into the coffee grounds under high pressure. These machines are cheaper and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their ability to create the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.
In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They make use of an air compressor to push hot water across the ground. They are also more mobile than steam-driven electric espresso machines.