How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly does it work?
Espresso is made by forcing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.
The Head of the Group
The name implies, the group head is the place you place your portafilter while making espresso. It is responsible for dispersing water into the portafilter before controlling the pressure of the extraction. There are a variety of types of group head each with its unique advantages and drawbacks. Some focus on temperature stability, while others on pre-infusion capabilities, while others are designed to control the lever. Some include a combination such as the E61. This is a favorite among baristas as it provides a variety of benefits in a single package.
As you can see in the photo above, the group head has numerous notches that you can place your portafilter before twisting it with your hands to lock it in. A gasket made of rubber is positioned in the notches to make a seal when you insert your portafilter. The notches allow for precise placement of your portafilter. This is crucial to ensure an efficient extraction.
The group head is not just able to allow you to place your portafilter easily, but it also maintains the same temperature. It does this by circulating hot water through the brew pan and around the portafilter, making sure that it is always at the right temperature for extraction. It is important to note that even a few degree deviation can make the difference between a great and a great espresso.
The Pump
In contrast to manual piston machines that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to provide the nine atmospheric bars of pressure that are required for espresso extraction. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger prior being shot through the ground coffee inside the group head.
Pumps tend to be cheaper than piston-driven models, and they tend to last longer, but both types of machines can become damaged due to excessive use and poor cleaning. They also increase the complexity of mechanical systems that can lead to costly prices for even the simplest models.
Some espresso machines use steam pressure instead of a pump to make espresso. This can result in over-extraction because the boiler here that produces steam also warms the water to boil. Additionally these machines typically have to restore their pressure between cups, which takes time and energy.
Many espresso machines make use of the 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 under high speed. Both machines can make excellent espresso, however rotary machines are quieter, more durable and less likely to break down.
The Boiler
The boiler is the component which heats the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter which holds the ground espresso and is then pumped down into the cup. The steam generates enough pressure to push the coffee grounds through. This creates a crema on the top of the espresso. This is a sign of a good espresso.
There are three different types of espresso machines, each with a different type of pump and brew temperature. There are a variety of ways to control the strength of the brew click here and the size of cup that can be made by the machine.
The first espresso machines were steam-type. They utilized one boiler to make both brew and steam, read more but the pressure they could produce was very low - just 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 producers Luigi Bezzerra & Desiderio Pavoni.
The most common espresso maker is a semi-automatic device that has an electric pump. When people think of espresso machines, they imagine these machines. With a semi-automatic machine you grind the beans and then tamp them by hand, but the pump provides regulated water flow and pressure. This is a great compromise between human control and mechanised consistency.
The Filter
Espresso machines typically use filters that separate the coffee grounds from the hot water. The filter is read more also a vital part of the machine's temperature control, as it helps prevent overheating.
Filters also aid in flavor as it allows for a longer flowering phase. This lets the beans release their flavor and also allows for better extraction.
It is important to remember that even the best filter can make a bad cup of coffee. The quality of the beans, and the extraction, are still crucial.
It's here that coffee machine the magic happens. This is what makes espresso taste so delicious. The grouphead, sometimes referred to as the brew head, is where the portafilter (the device you put the coffee grounds into) is placed when making espresso.
In an espresso machine that is driven by steam, hot water is heated in an airtight container to produce steam, which then pushes the hot water through the grounds at high pressure. These kinds of machines are typically less expensive and easier to maintain than pumps-driven models. They are however limited in their ability for creating the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent years, compressed air pump-driven espresso machines have become more popular. They use an air-compressor to push hot water across the ground and are much more mobile than steam-driven electric espresso machines.