How Does Machine Espresso Work?
Machine espresso utilizes precise pressure and incredible filter technology to produce the perfect cup of coffee. What exactly is it?
In order to make espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.
The Group Head
The name implies, the group head is where you place your portafilter when brewing espresso. It disperses the water into the portafilter and regulates the pressure of extraction. There are a variety of types of group heads each with its distinct advantages and drawbacks. Some are designed to provide stability in temperature, while others are specifically designed to handle pre-infusion. Others are built to control the lever. Some have a combination, like the E61. This is a favorite among baristas because it offers multiple advantages in a single package.
As you can see in the photo above, the group head has many notches in which you can put your portafilter, then twist it by hand to secure it. There is also a gasket made from rubber that resides inside the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches on the head permit a precise placement of the portafilter, which is vital for an efficient extraction.
The group head does not just allow you to put in your portafilter easily, but it also maintains the same temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is always at the right level for extraction. It is important to realize that even a few degree deviation can make the difference between a good and excellent espresso.
The Pump
Motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure that is required for espresso extraction. This differs from manual piston machines which use a lever. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head.
Pumps tend to be less expensive than piston-driven machines, and tend to last longer, although both types of machines can become damaged due to excessive use and poor cleaning. They also add mechanical complexity that can lead to the cost of even the most basic models.
Certain espresso machines eliminate the pump entirely and utilize steam pressure to make espresso. The drawback is that the boiler that produces steam also raises the temperature of water to boiling and can result in excessive extraction. These machines also have to continually rebuild their pressure between cups. This takes energy and time.
A large majority of espresso machines employ a rotary or vibration pump. A vibration model makes use of an oscillating disk to create pressure, while the rotary model pushes hot water through the ground at high speed. Both models can make read more excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the element that heats water to the ideal temperature to extract. The steam created reaches the portafilter, which holds the espresso grounds. It is then poured into the cup. The steam is able to create enough pressure to push the grounds of coffee through. This creates a layer crema that is then poured over. This is the hallmark of a good espresso.
There are three kinds of espresso makers, and they differ in the type of pump they use and how hot the coffee is. There are many ways to control the strength of the brew and the size of the cup that can be made by the machine.
The first espresso machines were steam-based. The earliest espresso machines were steam types. This led to the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso machine is a semiautomatic model with an electric pump. These are the things people think of when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the read more beans yourself however the pump controls the flow of water and pressure. This is a great compromise between the human touch and the mechanised consistency.
The Filter
Typically, espresso machines have filters to separate the coffee grounds as they pass through the hot water. The filter is also website an important part of the temperature control system as it prevents the machine from overheating.
It also improves flavor, as a filter lets you enjoy a longer bloom time. This allows the beans to release their flavor and gives an opportunity for better extraction.
It is important to keep in mind that even the best filter could result in a poor cup of coffee. The quality of the beans, and the extraction process, are still very important.
It's here that the magic takes place. This is what makes espresso taste so good. The grouphead, sometimes referred to as the brew head, is the place where the portafilter (the thing you put the coffee ground into) is placed when making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to make check here steam. The steam then pushes hot water through grounds of coffee under high pressure. They are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to create the ideal brewing conditions, since they are only operating at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.
In recent years, compressed air-driven espresso machines have become more popular. They make use of an air compressor to force hot water into the ground. They are also more mobile than electric steam-driven espresso website machines.