Don't Buy Into These "Trends" About Machine Espresso
Don't Buy Into These "Trends" About Machine Espresso
Blog Article
How Does Machine Espresso Work?
Machine espresso uses precision pressure and incredible filter technology to produce the perfect cup of coffee. What exactly is it that makes it work?
In order to make espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However it is the pressure that makes the main difference.
The Group Head
The group head is the portafilter you insert when brewing espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the resulting extraction. There are a variety of types of group head, each with their own advantages and drawbacks. Some are designed for temperature stability while others are designed to handle pre-infusion. Others are made to control the lever. Some are a combination, such as the E61. This is a very popular choice for baristas due to the fact that it has multiple benefits in a single package.
As you can see in the image above, the group head is fitted with several notches. You can place your portafilter in these notches and then turn the head around to secure it. There is also a rubber gasket that resides inside the notches to help create an airtight seal when you insert your portafilter into the machine. The notches on the head permit an exact placement of the portafilter, which is necessary for a consistent extraction.
Apart from allowing you easily insert your portafilter, the group head is also responsible for maintaining a consistent temperature. This is done 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. This is important, as even a few degrees can be the difference between a good and excellent espresso.
The Pump
The motorized pumps that are used in rotary espresso machines provide the nine atmospheric bar pressure needed for espresso extraction. This differs from manually operated piston machines that employ a lever. This pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger before being shot through the ground coffee in the group head.
Pumps are generally less expensive and last for longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of frequent use and poor cleaning. Pumps are also more complicated mechanically, and can add to prices of even most basic models.
Some espresso machines eliminate the pump completely and use steam pressure to brew espresso. The drawback of this is that the boiler that produces steam also raises the temperature of water to the point of boiling which could lead to over-extraction. The machines also need to constantly rebuild their pressure in between cups. This takes energy and time.
Many espresso machines use the rotary or vibration pump. A vibration model employs the vibrating disk to create pressure, whereas a rotating model pushes hot water through the ground at a rapid speed. Both machines can make excellent espresso, however rotary machines are more stable, quieter and less likely to break.
The Boiler
The boiler is used to heat the water to a temperature that is ideal to extract. The steam that is produced reaches the portafilter, which contains the ground espresso and gets funnelled down into the cup. During this process the steam is able to create enough pressure to push the grounds of the coffee through. This results in a whipped-up top of the espresso. This is one of the main characteristics of a good espresso.
There are three kinds of espresso machines, each having a different type of pump and the temperature of the brew. There are also different ways in which the brew could be controlled and the dimensions of the cup the machine can produce.
The earliest espresso machines were steam types. The first espresso machines were steam-type machines. This resulted in the coffee tasting burnt and bitter. This is the reason Milanese manufacturers Luigi espresso and filter coffee machine Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most well-known espresso machine is a semiautomatic that has an electric pump. This is what people envision when they think of an espresso machine. With a semi-automatic espresso machine, you must grind the beans and then tamp them yourself but the pump controls the flow of water and pressure. This is an excellent compromise between human touch and the mechanised quality.
The Filter
Typically, espresso machines use filters to separate the grounds of the coffee as they go through the hot water. The filter is also a vital element of the machine's temperature control, since it stops overheating.
It also enhances flavor, since a filter allows for a more prolonged bloom time. This helps the beans let their nuances out and provides the chance for better extraction.
It is important to remember that even the best filter can result in a bad cup of coffee. The quality of the beans and the extraction process, remain crucial.
This is where the magic happens, it's what makes an espresso really taste great. The grouphead, sometimes referred to as the brew head, is the place where the portafilter (the container you place the coffee ground into) is placed when you're making espresso.
Steam-driven espresso machines use hot water that is heated inside an airtight container to produce steam. The steam then pushes hot water through the grounds of coffee at high pressure. These machines are cheaper 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, espresso machines driven by compressed air-pump are becoming increasingly popular. They use an air compressor to force hot water through the grounds and are significantly more portable than steam-driven electric machines.