The Advanced Guide To Machine Espresso
How Does Machine Espresso Work?
The machine espresso utilizes precise pressure, as well as a filtering system that is awe-inspiring to make the coffee you enjoy. How exactly does it work?
To make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference.
The Group Head
The group head is the portafilter that is inserted when you are making espresso. It disperses water in the portafilter and regulates the pressure of extraction. There are various kinds of group heads each with its particular advantages and drawbacks. Some are specifically designed for stability of temperature while others are specifically designed to handle pre-infusion. Others are made to control the lever. Some include a combination like the E61. This is a favorite among baristas since it provides multiple advantages in one package.
As you can see in the above image the group head is made up of several notches to put your portafilter, then twist it with your hands to lock it in. There is also a gasket made of rubber that resides inside the notches, which helps create a seal when you insert your portafilter into the machine. The notches on the head allow for a precise placement of the portafilter, which is essential for a consistent extraction.
The group head does not just allow you to place your portafilter easily however, it also keeps a constant temperature. It does this by cycling hot water through the brew pan and around the portafilter to ensure that it's always at the right temperature for extraction. It is important to realize that even a small variation can mean the difference between a decent and a excellent espresso.
The Pump
The motorized pumps used in espresso machines that rotate provide the nine atmospheric bar pressure that is required to extract espresso. This is different from manual piston machines that use a lever. The pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger before being shot through the ground coffee inside the group head.
Pumps are generally cheaper and last longer than piston-driven machines. However, both types of machines may degrade because of frequent use and poor cleaning. Pumps are also more complex mechanically, which could increase the price of even the simpler models.
Some espresso machines employ steam pressure instead of a pump for brewing espresso. The downside is that the boiler that produces steam also increases the temperature of water to the point of boiling which can cause over-extraction. These machines also have to continuously rebuild their pressure between cups. This requires energy and time.
Many espresso machines make use of a rotary or vibration pump. A vibration model makes use of the vibrating disk to create pressure, whereas a rotary model pushes hot water through the ground at a fast speed. Both types of machine are capable of producing excellent espresso, however rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is the one that makes the water warm to the right temperature to extract. The steam that is created gets to the portafilter which is the container that holds the espresso coffee grounds. It is then funneled into the cup. During this process the steam is able to create enough pressure to push the grounds of the coffee through. This creates a crema on the top of the espresso. This is a sign of a great espresso.
There are three kinds of espresso makers. They differ in the kind of pump they use and how hot the espresso is. There are different ways to control the amount of brew, as well as the size of cup that can be made by the machine.
The first espresso machines were steam-types. The first espresso machines were steam-type machines. The coffee tasted bitter and burned. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most popular espresso maker is a semi-automatic machine with an electric pump. These are what people imagine when they think of an espresso machine. Semi-automatic machines require you to grind and tamp your beans yourself while the pump controls the water flow and pressure. This is a perfect compromise between human control and mechanized reliability.
The Filter
Espresso machines usually use filters that separate the grounds of the coffee from the hot water. The filter is also a crucial part of the temperature control system, as it keeps the machine from overheating.
Filters also aid in flavor as it allows for an extended flowering time. This helps the beans to let their nuances out and provides an opportunity for better extraction.
However, it is important to keep in mind that even a top filter can result in a poor cup of coffee as the quality of the beans and extraction is still important.
This is where the magic happens, it's the thing that makes espresso taste good. The grouphead, often referred to as the brew head, is the place where the portafilter (the thing you put the ground coffee into) is located when you're 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 at high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. They are however limited for creating the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In coffeee.uk , espresso machines driven by compressed air-pump are becoming increasingly popular. They utilize an air compressor to push the hot water through the grounds and are significantly more portable than steam-driven electric machines.