How Does Machine Espresso Work?
The machine espresso utilizes precision pressure, and filter technology that is awe-inspiring to make the coffee you enjoy. What exactly is it?
Espresso is created by forcing hot water at high pressure through finely ground coffee. The process is similar to making drip coffee. However, it is the pressure that makes the main difference.
The Group Head
The group head is the portafilter that you put in when making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the extraction. There are a variety of group heads each with their own advantages and disadvantages. Some are specifically designed for temperature stability while others are designed to handle pre-infusion. Others are built to control the lever. There are some that have a combination of features, like the E61, which is to be the most popular among baristas for its ability to provide multiple benefits in a single package.
As you can see from the photo above the group head is equipped with several notches. It is possible to place your portafilter in these notches and then turn the head around to secure it. A gasket made of rubber is positioned inside the notches to help create a seal as you insert your portafilter. The notches on the head permit an exact location of the portafilter which is essential for a consistent extraction.
The group head is not just able to allow you to place your portafilter easily however, it also keeps the temperature at a constant level. This is done by cycling hot water around the portafilter and through the brew-basket, ensuring the temperature is always right for extraction. This is vital, because even a few degrees can mean the difference between good and excellent espresso.
The Pump
In contrast to manual piston machines which use a lever to pressurize water, the rotary espresso machines use motorized pumps that provide the nine atmospheric bars of pressure necessary to extract espresso. This pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger before being pushed through the ground coffee inside the group head.
Pumps tend to be less expensive and last longer than piston-driven machines. However, both types of machines can degrade due to overuse and poor cleaning. Pumps are also more complex mechanically, which could increase the cost of even the simple models.
Some espresso machines eliminate the pump completely and instead utilize steam pressure to make espresso. The downside is that the same boiler that produces steam also increases the temperature of water to boiling and can result in over-extraction. These machines also have to continually rebuild their pressure between cups. This takes energy and time.
Many espresso machines employ either a rotary or vibration pump, with a vibrating model using a rotating disc to create the pressure, and rotating models that push hot water through the grounds under high speed. Both machines can make excellent espresso, however rotary machines are more quiet, durable and less likely to fail.
The Boiler
The boiler is the part that heats the water to the optimal temperature for extraction. The resulting steam is then transferred to the portafilter containing the ground espresso machine with frother (wwwcoffeeeuk37518.activoblog.com) and gets funnelled down into the cup. The steam causes enough pressure to push the coffee grounds through. This results in a whipped-up the top of the espresso. This is a hallmark of a great espresso.
There are three different types of espresso machines, each with a different type of pump and the temperature of the brew. There are various ways that the brew can be controlled and the size of the cup the machine is capable of making.
The first espresso machines uk machines were steam-based. They employed only one boiler to make both steam and brew, however, the pressure they could produce was very low – just two bars of atmospheric pressure at most. The coffee tasted bitter and burned. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso maker is a semiautomatic machine with an electric pump. These are the things people think of when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans on your own however the pump controls the flow of water and pressure. This is an excellent compromise between human touch and mechanized accuracy.
The Filter
espresso machine with frother (wwwcoffeeeuk37518.activoblog.com) machines usually use a filter that separates the grounds of coffee from hot water. The filter is also an essential element of the machine’s temperature control, since it stops overheating.
A filter can also help with flavor since it allows for a longer flowering period. This allows the beans to let their nuances out, and improves extraction.
It is important to remember that even the most efficient filter can produce a bad cup of coffee. The quality of the beans, and the extraction process, are still very important.
This is where the magic happens, and it’s what makes an espresso really taste great. The grouphead, sometimes called the brew head, is where the portafilter (the thingy you put the coffee ground into) sits when you’re making espresso.
Steam-driven espresso machines use hot water heated in an airtight container to make steam. The steam then pushes hot water through coffee grounds under high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, compressed air pump-driven espresso machines have become more popular. They make use of an air compressor to push hot water across the ground and are much more mobile than electric steam-driven retro espresso maker machines.