How Does Machine Espresso Work?
Machine espresso employs precise pressure and amazing filter technology to make the perfect cup of coffee. How exactly does it work?
Espresso is made by pushing hot water under high pressure through finely-ground coffee. The process is similar to that of making drip coffee. However, the pressure is the main difference.
The Group Head
The group head is the portafilter that you insert when brewing buy espresso makers. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the extraction. There are numerous kinds of group heads, each with its own advantages and disadvantages. Some are specifically designed for stability in temperature, while others are specifically designed to handle pre-infusion. Some are designed to control the lever. There are even some that have a combination of features, like the E61 one, which is to be the most popular among baristas for its ability to offer multiple perks in a single package.
As you can see in the picture above the head of the group is fitted with a variety of notches. You place your portafilter in these notches and then turn the head around 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 allow for an exact placement of the portafilter. This is essential for a consistent extraction.
The group head not only lets the portafilter to be inserted easily however it also keeps the same temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is constant to extract the coffee. This is important, as even a small difference in temperature can make the difference between a good and great espresso.
The Pump
The motorized pumps that are used in rotary espresso machines provide the nine atmospheric bar pressure needed to extract espresso. This is different from manually operated piston machines that employ a lever. This pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pushed through the ground coffee in the group head.
Pumps tend to be cheaper than piston-driven machines and tend to last longer, however both types of machine can degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, and can add to prices of even most basic models.
Some espresso machines make use of steam pressure instead of a pump to make espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of water until it reaches boiling which can cause 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 either a vibration or rotary pump. A vibration model employs the vibrating disk to create pressure, whereas the rotating model pushes hot water through the ground at a high speed. Both machines can make great espresso but rotary machines are quieter, more durable and less likely to fail.
The Boiler
The boiler makes the water warm to the right temperature for extraction. The resultant steam then reaches the portafilter that contains the ground Espresso machine uk (https://coffeee08135.wikijournalist.com/4782974/How_to_choose_the_right_electric_espresso_maker_online) coffee, and is then pumped down into the cup. During this process the steam is able to create enough pressure to push the grounds of the coffee through. This results in a layer of crema on top. This is the hallmark of a good espresso.
There are three types of espresso makers, which differ in the type of pump they employ and how hot the brew is. There are also different ways in which the brew could be controlled as well as the dimensions of the cup the maker can create.
The first espresso machines were steam-types. They employed one boiler to make both steam and brew, but the pressure they could generate was low - only two bars of atmospheric pressure maximum. This resulted in the coffee tasting bitter and burnt. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most commonly used espresso machine is a semiautomatic with an electric pump. These are the things people think of when they think of an espresso machine. With a semi-automatic machine you need to grind the beans and then tamp them by hand. The pump regulates the flow of water and pressure. This is a great compromise between the human touch and the mechanized accuracy.
Espresso machines typically have a filter that separates the coffee grounds from the hot water. The filter is also an essential component of the machine's temp control, as it helps prevent overheating.
A filter also improves flavor because it allows for a longer flowering phase. This lets the beans release their flavor and allows for a better extraction.
It is important to keep in mind that even the most efficient filter can make a bad cup of coffee. The quality of the beans and the extraction process are still crucial.
It's here that the magic occurs. This is the reason why espresso tastes so good. The grouphead, sometimes called the brew head, is the place where the portafilter (the thingy you put the coffee ground into) is located when you're making espresso.
Steam-driven buy espresso makers machines make use of hot water that is heated in an airtight container to create steam. The steam then moves hot water through the grounds of coffee at high pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. They are however limited to create the perfect conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent years, travel espresso maker machines powered by a compressed air pump have become increasingly popular. They use an air compressor to push hot water through grounds and are more portable than steam-driven electric machines.(Image: https://cdn.freshstore.cloud/template/images/778/14409/coffeee-logo-300x100-png.png)
