5 Killer Quora Answers On Machine Espresso
How Does Machine Espresso Work?
Machine espresso uses precision pressure and amazing filter technology to make the coffee we love. What exactly is it that makes it work?
Espresso is produced by pushing hot water 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 Head of the Group
As the name suggests, the group head is where you put your portafilter in when brewing espresso. It distributes water into the portafilter, and controls the pressure of the extraction. There are numerous kinds of group heads each with distinct advantages and drawbacks. Some are specifically designed for stability of temperature while others are designed to handle pre-infusion. Others are made to control the lever. Some have a combination, such as the E61. This is a popular choice among baristas since it provides multiple benefits in one package.
As you can see from the above photo the head of the group is equipped with several notches. You can place your portafilter in these notches and then turn the head around to secure it. There is also a gasket made from rubber in the notches and helps to create a seal when you insert your portafilter into the machine. The notches on the head permit an exact placement of the portafilter, which is essential to ensure an efficient extraction.
Apart from allowing you easily place your portafilter in, the group head is also responsible for maintaining a consistent temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is constant for extraction. This is important because even a few degrees can make the difference between excellent and great espresso.
The Pump
In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure that are required to extract espresso. The pressure is created by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pumped through the ground coffee in the group head.
Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which can increase the cost of even simplest models.
Certain espresso machines remove the pump completely and use steam pressure to brew espresso. The disadvantage of this is that the same boiler that produces steam also raises the temperature of water to boiling and can result in excessive extraction. They also have to constantly rebuild their pressure in between cups. This takes energy and time.
Many espresso machines employ either a rotary or vibration pump, which is a vibration model using a rotating disc to create the pressure, and a rotary model pushing hot water through the grounds under high speed. Both models are capable of producing excellent espresso, but Rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is the component that heats water to an optimal temperature for extraction. The resultant steam then reaches the portafilter which holds the ground espresso coffee and is then pumped into the cup. During this process the steam creates enough pressure to push the grounds of coffee through. This results in a whipped-up top of the espresso. This is a hallmark of a good espresso.
There are three types of espresso makers, which differ in the type of pump they use and the degree of heat that the espresso is. There are various ways to control the strength of the brew and the size of the cup that can be produced by the machine.
The first espresso machines were steam types. They employed only one boiler to make steam and brew, however the pressure they were able to produce was not very high - two bars of atmospheric pressure, at most. This led to the coffee tasting burnt and bitter. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most popular espresso maker is a semi-automatic one with an electric pump. These are what people imagine when they think of an espresso maker. With a semi-automatic espresso machine, you have to grind the beans and tamp them by hand. The pump controls the flow of water and pressure. This is a great combination of human control and mechanized reliability.
The Filter
Espresso machines usually have filters that separate the grounds of coffee from hot water. The filter is also a vital element of the temperature control system, as it keeps the machine from overheating.
A filter also helps with flavor because it allows for a longer flowering period. This lets the beans release their nuances, and also allows for better extraction.
However, it is important to remember that even a good filter can produce a bad cup of coffee, since the quality of the beans and extraction is important.
machine espresso 's in this area that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead, also referred to as the brew head, is the place where the portafilter (the thingy you put the coffee ground into) sits when you're making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to make steam. The steam then pushes hot water through grounds of the coffee under pressure. They are less expensive and easier for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.
In recent times, espresso machines powered by a compressed air compressor have become increasingly popular. They utilize an air compressor to force the hot water through the grounds and are more portable than steam-driven electric machines.