How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the coffee we love. How exactly does it work?
To make an barista espresso machine hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference.
The Head of the Group
The group head is the portafilter that you place in the espresso maker when making it. It distributes water into the portafilter, and then controls the pressure of the extraction. There are a variety of types of group head, each with their unique advantages and disadvantages. Some focus on temperature stability, some on pre-infusion features, and others are designed to control the lever. There are some that contain a variety of features, such as the E61, which is the standard choice for many baristas due to its ability to provide multiple benefits in one package.
As you can see in the above photo, the group head has numerous notches that you can place your portafilter and then twist it with your hands to lock it in. There is also a rubber gasket that is a part of the notches and helps to create the seal when you insert your portafilter into the machine. The notches on the head permit a precise position of the portafilter which is necessary to ensure a consistent extraction.
Aside from allowing you to effortlessly insert your portafilter the group head is also responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew basket, and around the portafilter, ensuring that it’s always at the right temperature to extract. This is important, as even a few degrees can make the difference between a excellent and great espresso.
The Pump
Motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure that is required to extract espresso. This differs from manual piston machines that rely on levers. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger prior being pumped through the ground coffee in the group head.
Pumps are typically less expensive and last for longer than piston-driven machines. However, both types of machines can deteriorate due to excessive use and insufficient cleaning. They also make mechanically complex, which can result in an expensive price for even the simplest models.
Certain espresso machines remove the pump completely and instead use steam pressure to brew espresso. The drawback is that the same boiler that produces steam also raises the temperature of the water to the point of boiling which could lead to over-extraction. They also have to continually rebuild their pressure between cups. This requires energy and time.
A large majority of espresso machines employ either a vibration or rotary pump. A vibration model makes use of the vibrating disk to create pressure, while the circular model pushes hot liquid through the ground at high speed. Both machines produce great espresso but rotary machines are quieter, more durable and less likely to break.
The Boiler
The boiler is the one that heats the water to the right temperature for extraction. The steam produced gets to the portafilter which is the container that holds the best espresso machine uk coffee grounds. The steam is then channeled into the cup. The steam causes enough pressure to push the grounds of the coffee through. This results in a whipped-up top of the espresso. This is a hallmark of a great espresso.
There are three types of espresso machines for home machines, each having a different type of pump and brew temperature. There are many ways to control the amount of brew, as well as the size of cup that can be produced by the machine.
The first espresso coffee machine for home machines were steam-based. They utilized only one boiler to make both steam and brew but the pressure they could produce was not very high – two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most commonly used espresso machine is a semiautomatic that has an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine you grind the beans and then tamp them yourself but the pump provides regulated water flow and pressure. This is a great compromise between the human touch and the mechanised consistency.
The Filter
Typically, espresso machines have filters that separate the grounds of coffee when they pass through the hot water. The filter is also a vital element of the machine’s temperature control, since it stops overheating.
It also enhances flavor as a filter lets you enjoy a longer bloom time. This allows beans to release their flavor and gives an opportunity to improve extraction.
It is important to keep in mind that even the most efficient filter can result in a bad 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 great. The grouphead, sometimes referred to as the brew head, is the place where the portafilter (the container you place the coffee grounds into) is placed when making espresso maker for home.
In the steam-driven espresso machine hot water is heated in an airtight container to create steam. This is then pushed through the grounds under high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect brewing conditions since they are only operating at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.
In recent years, espresso machines powered by a compressed air compressor have become increasingly popular. They utilize an air compressor to force hot water through grounds, and are far more portable than steam-driven electric machines.