Don't Buy Into These "Trends" Concerning Machine Espresso
Don't Buy Into These "Trends" Concerning Machine Espresso
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How Does Machine Espresso Work?
Machine espresso utilizes precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. How exactly does it work?
To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the primary difference.
The Head of the Group
The name implies the group head is the place you place your portafilter while brewing espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the resulting extraction. There are many different types of group heads each with its own advantages and drawbacks. Some are specifically designed for stability of temperature while others are built to handle pre-infusion. Others are made to control the lever. Some include a combination like the E61. This is a preferred choice for baristas because it offers multiple benefits in one package.
As you can see from the picture above the group head is fitted with a variety of notches. The portafilter is placed in these notches, then turn the head around to secure it. A rubber gasket is located inside the notches, which helps make a seal when you insert your portafilter. The notches allow for an exact placement of the portafilter. This is crucial to ensure an accurate extraction.
The group head is not just able to allow you to place your portafilter easily however it also keeps the same temperature. It does this by cycling hot water through the brew basket, and around the portafilter, ensuring that it is always at the right temperature to extract. This is important, as even a small difference in temperature can mean the difference between good and great espresso.
The Pump
The motorized pumps that are used in espresso machines rotary provide nine atmospheric bar pressure that is required for espresso extraction. This differs from manual piston machines that rely on a lever. The pressure is built by pumping water through a heat exchanger and then through the ground coffee.
Pumps tend to be less expensive and last for longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of excessive use and poor cleaning. They also make mechanically complex that can lead to costly prices for even the most basic models.
Certain espresso machines can eliminate the pump completely and utilize steam pressure to make espresso. The drawback of this is that the boiler that produces steam also raises the temperature of the water until it reaches boiling and can result in excessive extraction. The machines must also continually rebuild their pressure between cups. This takes energy and time.
A large majority of espresso machines employ an rotary or a vibration pump. A vibration model utilizes the vibrating disk to create pressure, whereas the Rotary model pushes hot coffee through the ground at a rapid speed. Both types of machine can make a great espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler heats the water to the ideal temperature to extract. The resulting steam is then transferred to the portafilter containing the ground espresso coffee and is then funneled down into the cup. During this process, the steam creates pressure and pushes through the coffee grounds. This results in a whipped-up the top of the espresso. This is one of the hallmarks of a good espresso.
There are three kinds of espresso makers, which differ in the type of pump they employ and how hot the brew is. There are also different ways in which the brew can be controlled and the size of the cup that the machine can produce.
The earliest espresso machines were steam types. They used a single boiler to make both steam and brew, however the pressure they were able to create was minimal - two bars of atmospheric pressure at most. The coffee tasted bitter and burned. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso maker is a semi-automatic device with an electric pump. These are what people imagine when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the water flow and pressure. This is an excellent compromise between human touch and the mechanised accuracy.
The Filter
Typically, espresso machines employ a filter to separate out the grounds of coffee as they move through the hot water. The filter is also a vital part of the temperature control system, as it prevents the machine from overheating.
It also improves flavor, as a filter allows for a longer bloom phase. This helps the beans to let their nuances out and provides the chance for better extraction.
It is important to keep in mind that even the most efficient filter can result in a bad cup of coffee. The quality of the beans, and the extraction, are still very important.
It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead, often referred to as the brew head, is the place where the portafilter (the container you place the ground coffee in) is located when you're making espresso.
In a steam-driven espresso machine hot water is heated in an airtight container to produce steam, which is then pushed through the grounds with high pressure. These kinds of machines are typically check here less expensive and simpler to maintain than pump-driven models. They are however limited to create the perfect brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent years, espresso machines powered by a compressed air compressor have become increasingly popular. They use an air compressor to force hot water through the grounds and are much more portable than electric steam-driven machines.