How Does Machine Espresso Work?
The machine espresso uses precise pressure and filtering technology that is amazing to make the coffee you love. What exactly is it that makes it work?
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
As the name suggests the group head is where you place your portafilter while making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the extraction. There are many different kinds of group head, each with their particular advantages and disadvantages. Some focus on temperature stability, others on pre-infusion options, and others are designed to control the lever. There are some that contain a variety of features, like the E61 that is the standard choice for many baristas due to its capacity to offer multiple benefits in one package.
As you can see in the image above the group head is fitted with a variety of notches. It is possible to place your portafilter into these notches and turn the head around to secure it. A rubber gasket is located inside the notches, which helps create a seal while you insert your portafilter. The notches permit the precise placement of the portafilter. This is crucial to ensure an even extraction.
The group head does not just allow the portafilter to be inserted easily however, it also keeps an even temperature. It does this by circulating hot water through the brew basket, and around the portafilter, ensuring that it is always at the correct temperature to extract. It is important to note that even a few degree variation can mean the difference between a good and a great espresso maker for home.
The Pump
In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure that are required to extract espresso. The pressure is created by removing tap water from a reservoir, and pumping it through a heat exchanger before it is shot through the ground coffee in the group head.
Pumps are typically less expensive than piston-driven machines, and they tend to last longer. However, both types of machines could be damaged by excessive use and inadequate cleaning. They also make mechanically complex which can result in costly prices for even the most basic models.
Certain espresso machines utilize steam pressure instead of a pump in order to brew espresso. This could lead to over-extraction since the boiler that produces steam also causes the water to boil. The machines must also constantly rebuild their pressure between cups. This takes energy and time.
Many espresso machines utilize either a rotary or vibration pump, which has a vibration model that uses a vibrating disc to generate the pressure and rotating models that push hot water through the grounds at high speed. Both machines produce great espresso but rotary machines are more quiet, durable and less likely to break down.
The Boiler
The boiler is the component which heats the water to the optimal temperature for extraction. The steam that is created will eventually reach the portafilter, which holds the espresso grounds. The steam is then channeled into the cup. During this process, steam creates pressure to push through the grounds of the coffee. This results in a layer crema on top. This is the hallmark of a good espresso.
There are three kinds of espresso makers, and they differ in the type of pump they employ and the degree of heat that the espresso is. There are also different ways in which the brew could be controlled, as well as the dimensions of the cup the machine is capable of making.
The first espresso machines were steam-type. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burned. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most common espresso machine is a semiautomatic that has an electric pump. These are the images people have when they imagine an espresso machine sale machine. With a semi-automatic espresso machine, you have to grind the beans and tamp them by hand. However, the pump provides regulated water flow and pressure. This is an excellent combination of human control and mechanised reliability.
The Filter
Typically, espresso machines have filters that separate the coffee grounds as they pass through the hot water. The filter is also a crucial part of the temperature control system, since it helps prevent the machine from overheating.
It also aids in flavor, since a filter can allow for a longer bloom phase. This lets the beans release their nuances, and also allows for better extraction.
However, it is important to keep in mind that even a high-quality filter could result in a bad cup of coffee as the quality of the beans and extraction is 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 place the portafilter, the thingy used to place the coffee grounds in, when making espresso.
In the steam-driven espresso machine hot water is heated in an airtight tank to produce steam, which then pushes the hot water through the grounds under high pressure. These types of machines are typically cheaper and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect 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 been gaining popularity. They make use of an air compressor to force hot water through the best ground coffee for espresso machine (josepho912ztl6.get-blogging.com published an article), and are more mobile than steam-driven electric espresso maker espresso machines.