How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. How exactly does it work?
To make an espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, but the difference is in the pressure.
The Head of the Group
The group head is the portafilter you insert when brewing espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure that results from the extraction. There are several different types of group heads, each with their unique advantages and drawbacks. Some are specifically designed for the stability of temperature while some are designed to handle pre-infusion. Some are designed to control the lever. Some are a combination, like the E61. This is a favorite among baristas because it offers multiple advantages in one package.
As you can see from the picture above the group head is fitted with several notches. You can place your portafilter into these notches and twist the head to lock it. There is also a gasket made from rubber which is located inside the notches, which helps create a seal when you insert your portafilter into the machine. The notches allow for precise placement of the portafilter. This is vital for an accurate extraction.
Apart from allowing you easily connect your portafilter, the group head is also responsible to ensure that the temperature remains even. It does this by cycling hot water through the brew basket, and around the portafilter, making sure that it is always at the right temperature to extract. It is important to note that even a small differences can make the distinction between a good and a great espresso coffee machine uk.
The Pump
The motorized pumps in rotary espresso machines supply the nine atmospheric bar pressure that is required for espresso extraction. This is different from manually operated piston machines that employ levers. The pressure is created by removing tap water from a reservoir and pumping it through a heat exchanger before being shot through the ground coffee in the group head.
Pumps are generally less expensive and last longer than piston-driven machines. However, both types of machines are susceptible to degrading due to excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which could increase prices of even simple models.
Certain espresso machines eliminate the pump entirely and employ steam pressure to create espresso machine sale. This can cause over-extraction because the boiler that produces steam also heats the water until it comes to a boil. The machines must also continuously rebuild their pressure between cups. This requires energy and time.
Many espresso machines make use of either a vibration or rotary pump. A vibration model uses the vibrating disk to create pressure, while the rotary model pushes hot water through the ground at high speed. Both machines produce great espresso, however rotary machines are quieter, more durable and less likely to break down.
The Boiler
The boiler is the component that heats the water to the optimal temperature to extract. The steam that is produced reaches the portafilter containing ground espresso beans and is then pumped into the cup. During this process, the steam creates pressure that pushes through the grounds of the coffee. This results in a layer crema on top. This is a hallmark of a good espresso.
There are three kinds of espresso machines, each having different pumps and the temperature of the brew. There are also different ways in which the brew could be controlled and the size of the cup that the machine can make.
The first espresso machines were steam type. They employed only one boiler to make both steam and brew, but the pressure they could generate was low - only two bars of atmospheric pressure at the most. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most well-known espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they imagine these machines. With a semi-automatic espresso machine, you need to grind the beans and then tamp them by hand, but the pump controls the flow of water and pressure. This is a fantastic combination of human control and mechanized accuracy.
The Filter
Typically, espresso machines use filters to separate the coffee grounds as they pass through the hot water. The filter is also a vital part of the temperature control system since it helps prevent the machine from overheating.
A filter can also help with flavor as it allows for an extended flowering time. This allows the beans to release their flavor and also allows for better extraction.
It is important to remember that even the most efficient filter can result in a bad cup of coffee. The quality of the beans and the extraction, are still crucial.
This is where the magic happens, it's the thing that makes espresso taste great. The grouphead (also called the brewhead) is where you put the portafilter, which is the thingy that you put the grounds of coffee into when making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to make steam. The steam then pushes hot water through grounds of the coffee under pressure. These machines are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the ideal brewing conditions, since they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.
In recent years, compressed-air-pump-driven espresso machine with grinder machines have been gaining popularity. They make use of an air compressor to push hot water across the ground, and are more mobile than steam-driven electric espresso machines.