How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. What exactly is it?
Espresso is created 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 Group Head
The group head is the portafilter you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter and controlling the pressure that results from the extraction. There are numerous kinds of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion capabilities, and still others are designed to control the lever. There are also some that include a mix of features, like the E61 that is to be the most popular among baristas because of its ability to offer multiple benefits in one package.
As you can see in the image above The group head features many notches in which you can place your portafilter and twist it by hand to lock it in. A gasket made of rubber is positioned within the notches to make a seal when you insert your portafilter. The notches permit precise placement of the portafilter. This is vital for an accurate extraction.
Aside from allowing you to easily insert your portafilter, the group head is also responsible to maintain an even temperature. This is achieved by cycling hot water around the portafilter and through the brew-basket, making sure that the temperature is at the right level for extraction. It is important to note that even a few degree difference can make the difference between a good and great espresso.
The Pump
The motorized pumps that are used in rotary espresso machines supply the nine atmospheric bar pressure that is required for espresso extraction. This is different from manual piston machines that rely on levers. The pressure builds up by removing 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 tend to be cheaper than piston-driven machines, and tend to last longer, although both types of machines may get damaged through overuse and lack of cleaning. They also create mechanical complexity which can result in an expensive price for even the simplest models.
Some espresso machines make use of steam pressure instead of a pump to make Barista Espresso Coffee Machine. The drawback is that the same boiler that produces steam also raises the temperature of the water to boiling which could lead to excessive extraction. The machines must also continuously rebuild their pressure between cups. This requires energy and time.
Many espresso machines use the rotary or vibration pump. A vibration model employs an oscillating disk to create pressure, while a Rotary model pushes hot coffee through the ground at a rapid speed. Both machines can make excellent espresso however rotary machines tend to be more stable, quieter and less likely to break down.
The Boiler
The boiler makes the water warm to a temperature that is ideal to extract. The resulting steam is then transferred to the portafilter containing ground espresso beans and is then funneled down into the cup. The steam creates pressure that pushes through the coffee grounds. This results in a crema on the top of the espresso. This is one of the hallmarks of a good espresso machines for home.
There are three types of espresso machines, each having different pumps and the temperature of the brew. There are various ways in which the brew can be controlled and the size of the cup the machine can produce.
The first espresso machines were steam-types. They used a single boiler to make steam and brew, but 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 well-known espresso maker for home maker is a semi-automatic espresso machine device with an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the flow of water and pressure. This is a great compromise between human control and mechanized accuracy.
The Filter
Espresso machines usually use a filter that separates the grounds of coffee from hot water. The filter is also an essential component of the temperature control system because it stops the machine from overheating.
It also improves flavor, as it allows for a more prolonged bloom time. This helps the beans let their nuances out and provides an opportunity for a better extraction.
It is important to keep in mind that even the best filter could result in a poor cup of coffee. The quality of the beans and the extraction, are still very important.
It's in this area that the magic happens. This is what makes barista espresso coffee machine taste so good. The grouphead, often called the brew head, is the place where the portafilter (the container you place the ground coffee into) is placed when making espresso.
Steam-driven espresso machines espresso use hot water that is heated in an airtight vessel to create steam. The steam then pushes hot water through the grounds of coffee at high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the perfect brewing conditions as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.
(Image: https://cdn.freshstore.cloud/offer/images/778/8339/beko-cep5152b-espresso-pump-coffee-machine-15-bar-1200ml-tank-black-8339.jpg)In recent years, compressed air-pump-driven espresso machines have become more popular. They utilize an air compressor to push hot water across the ground and are more mobile than electric steam-driven espresso machines.
