9 Things Your Parents Teach You About Machine Espresso
How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. What exactly is it that makes it work?
In order to make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, but the key difference is in the pressure.
The Group Head
The group head is the portafilter that you place in the espresso maker when making it. It disperses water into the portafilter, and regulates the pressure of the extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are focused on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. There are some that come with a range of features, such as the E61, which is the most popular choice among baristas because of its ability to offer multiple perks in a single package.
As you can see in the above image the group head is made up of many notches in which you can place your portafilter before twisting it with your hands to secure it. A rubber gasket is located in the notches to create a seal as you insert your portafilter. The notches permit precise placement of your portafilter. This is crucial for an even extraction.
In addition to allowing you to easily connect your portafilter, the group head is responsible for maintaining an even temperature. This is done by cycling hot water around the portafilter, and through the brew-basket to ensure the temperature is always right to extract the coffee. It is crucial to keep in mind that even a small difference can make the difference between a decent and a excellent espresso.
The Pump
Contrary to manual piston machines which use a lever to pressurize water, the rotary espresso machines use motorized pumps that provide the nine atmospheric bars of pressure necessary for espresso extraction. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are generally more affordable and last longer than piston-driven machines. However, both types of machines can deteriorate due to overuse and inadequate cleaning. They also make mechanically complex and can lead to costly prices for even the simplest models.
Some espresso machines eliminate the pump completely and make use of steam pressure to make espresso. This can lead to over-extraction as the boiler that makes steam also warms the water to boil. The machines must also continually rebuild their pressure between cups. This takes energy and time.
Many espresso machines employ either a rotary or vibration pump, with a vibration model using a vibrating disc that generates the pressure, and a rotary model pushing hot water through the grounds at high speed. Both models can make a great espresso, but Rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is what is used to heat the water to a temperature that is ideal to extract. The steam produced reaches the portafilter, which contains the espresso coffee grounds. It is then funneled into the cup. During this process, the steam creates pressure and pushes through the grounds of the coffee. This creates a crema on the top of the espresso. This is one of the hallmarks of a good espresso.
There are three types of espresso makers, which differ in the kind of pump they use and the degree of heat that the espresso is. There are different ways in which the brew can be controlled and the dimensions of the cup the machine can produce.
The earliest espresso machines were steam-based. The earliest espresso machines were steam types. This led to the coffee tasting bitter and burnt. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most commonly used espresso machine is a semiautomatic model with an electric pump. These are the things people think of when they imagine an espresso machine. With a semi-automatic best espresso maker machine, you grind the beans and tamp them yourself but the pump provides regulated water flow and pressure. This is a great compromise between the human touch and mechanized quality.
The Filter
espresso machine with frother machines usually have filters that separate the grounds of the coffee from the hot water. The filter is also an important component of the temperature control system as it keeps the machine from overheating.
It also helps with flavor, since a filter lets you enjoy a longer bloom phase. This allows the beans to release their flavor and improves extraction.
It is important to keep in mind that even the most efficient filter could result in a poor cup of coffee. The quality of the beans, and the extraction process, remain vital.
It's here that the magic occurs. This is the reason why espresso tastes so good. The grouphead (also called the brewhead) is where you put the portafilter - the thingy used to place the grounds of your coffee into while making espresso.
Steam-driven espresso machines use hot water heated in an airtight vessel to create steam. The steam then pushes hot water into the coffee grounds under high pressure. These types of machines are typically cheaper and easier to maintain than pump-driven models. However, they are not as efficient in their ability to provide the perfect brewing conditions since they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.
In recent years, professional espresso machine machines driven by compressed air-pump are becoming increasingly popular. They utilize an air compressor to force hot water into the ground, and are more mobile than steam-driven electric espresso machines.