How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and amazing filter technology to make the delicious coffee we enjoy. But how exactly does it work?
To make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the main difference.
The Head of the Group
The group head is the portafilter you place in the espresso maker when making it. It is responsible for dispersing the water into the portafilter, and controlling the pressure that results from the extraction. There are a variety of types of group heads, each with their unique advantages and drawbacks. Some focus on temperature stability, others on pre-infusion capabilities, and still others are designed to control the lever. There are some that contain a variety of features, such as the E61 one, which is the standard choice for many baristas for its ability to offer multiple perks in one package.
As you can see in the above photo the group head comes with many notches in which you can place your portafilter and twist it by hand to lock it in. A gasket made of rubber is placed inside the notches, which helps create a seal when you insert your portafilter. The notches on the head allow for an exact location of the portafilter which is necessary for an even extraction.
The group head not only lets the portafilter to be inserted easily but also maintains a constant temperature. This is accomplished by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is always at the right level to extract the coffee. It is important to realize that even a tiny difference can make the difference between a good and great espresso.
The Pump
The motorized pumps in espresso machines rotary provide nine atmospheric bars of pressure required to extract espresso. This differs from manual piston machines that rely on levers. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior being pushed through the ground coffee in the group head.
Pumps tend to be less expensive than piston-driven models, and they tend to last longer, but both types of machine can degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, which could increase the cost of even the most basic models.
Some 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 can cause over-extraction. The machines must also constantly rebuild their pressure between cups. This requires energy and time.
Many espresso machines use an rotary or a vibration pump. A vibration model utilizes the vibrating disk to create pressure, while a rotary model pushes hot water through the ground at a rapid speed. Both models can produce an excellent espresso, but rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler heats the water to a temperature that is ideal for extraction. The resulting steam reaches the portafilter, which contains the ground espresso coffee, and is then pumped 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. coffeee.uk is a hallmark of a good espresso.
There are three kinds of espresso machines, each with different types of pumps and brew temperature. There are many ways to control the brew as well as the size of the cup that can be produced by the machine.
The earliest espresso machines were steam types. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burned. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most well-known espresso machine is a semiautomatic that has an electric pump. These are the things people think of when they think of an espresso maker. With a semi-automatic machine you grind the beans and tamp them by hand. The pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanised quality.
The Filter
Typically, espresso machines utilize filters to separate the grounds of coffee when they pass through the hot water. The filter is also an essential element of the machine's temperature control, since it helps to prevent overheating.
It also enhances flavor, since a filter lets you enjoy a longer bloom time. This helps the beans to release their nuances and gives an opportunity for a better extraction.
It is important to remember that even the finest filter could result in a poor cup of coffee. The quality of the beans as well as the extraction, remain vital.
This is where the magic happens, and it's what makes espresso taste good. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy that you put the coffee grounds in, while making espresso.
Steam-driven espresso machines make use of hot water that is heated inside an airtight container to create steam. The steam then moves hot water through the coffee grounds under high pressure. These kinds of machines are typically less expensive and easier to maintain than pumps-driven models. However, they are limited in their capacity to create the ideal 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, compressed air pump-driven espresso machines have become more popular. They make use of an air compressor to force hot water into the ground, and are more mobile than steam-driven electric espresso machines.