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What is an Espresso Machine?

Posted By: Aabree Coffee
Posted At: Nov 28, 2011 at 8:33 AM
Related Categories: Espresso Machine Guides

What is an espresso machine? The short answer: A machine that makes espresso. Okay, so you probably already figured that out. However, espresso is a specific thing that is made in a specific way, and so to make it, you need to have a machine that produces a specific environment for a proper brew. So maybe we should start with a quick recap of what espresso is. Specifically.

Espresso is a beverage that is produced by pushing hot water (between 190F and 195F in temperature) at high pressure (between 8 and 9 bars, or 135 PSI) through a bed of finely ground, compacted coffee. A normal single shot of espresso is approximately 1 to 1.5 ounces of liquid, using approximately 7 grams of ground coffee. A normal double shot is between 2 and 2.5 ounces, using double the volume of coffee grounds. When brewed properly, the resulting beverage is topped with a dark golden cream, called crema.

Therefore, at its simplest, an espresso machine must do all of the following:

  • Produce brewing water that is between 190 and 195 degrees F in temperature by means of an internal boiler or a thermoblock device.
  • Channel water into the brewing chamber (grouphead).
  • Deliver the water to coffee grounds (in the portafilter attached to the grouphead) at approximately 9 BAR or 135 PSI of pressure by using a pump, a spring system, or a lever.
  • Provide an exit for brewed espresso to be released into your cup.

That's pretty much what an espresso machine is. The result of the above parameters is that using an espresso machine, a shot of espresso can be brewed in under 30 seconds. When you consider most automatic drip coffee makers take 8 or 10 minutes to brew, espresso, which means fast or quick in loose Italian translation, suddenly seems very appropriately named. You should also keep in mind that all espresso machines also include a steam wand that can dispense hot water for tea or hot chocolate or steam so that you can froth and steam milk for delicious cappuccinos and lattes.

But even though espresso machines are similar in all the ways listed above, different types of espresso machines use different means to reach the same end. Let’s take a closer look at these varying methods.

Manual or “Piston” Espresso Machines

Manual machines were the first “real” espresso machines (those that met the requirements above) to be developed, and are still widely popular today. The machines consist of a large boiler that holds and heats all of the water necessary for brewing and steaming/frothing milk. When the boiler is at the correct temperature for brewing espresso, the operator simply lifts the lever, which raises a piston inside the grouphead. Water begins to flow from the boiler into the grouphead and seeps down through the coffee grounds in the portafilter. The coffee begins to drip from the spouts into your cup. When this happens the lever is then pressed down - also pushing the piston down and plunging the rest of the water through the coffee grounds. When the lever is pushed all of the way down, the brew cycle or extraction of espresso is complete and then you can repeat the process to make more espresso. With a piston lever espresso machine, you act as the machine's pump, applying direct pressure by means of the lever and pushing brew water through a finely ground, compacted bed of ground coffee at pressures of 8 BAR or greater.

These machines are not very easy to figure out at first, but they reward the diligent. Those who invest hours or days of practice with the machine can become true espresso connoisseurs that can literally "pull" the most amazing shots possible. As you can see, these machines are not necessarily for weekend warrior espresso fans. These machines are for the diehard espresso lover. But if cappuccino, lattes, or mochas are your thing, then their large boilers provide ample steam for producing perfect foamed and steamed milk.

For the most part, lever style machines have been pushed aside by modern technology and the desire for great espresso with less effort. Electric pump driven machines with sophisticated temperature and pressure monitoring devices and computers are the way of the future it seems, but it will be tough to replace the old world charm and reliable function of the lever espresso machine. La Pavoni and Gaggia continue the hand build the functional work of art to this day.

Semi Automatic Espresso Machines

Semi automatic machines use an electric water pump as opposed to the lever and piston design. They have a separate water reservoir where water is stored until it is pulled into the boiler to be heated and used for brewing or steaming/frothing milk. In short, these machines make the production of espresso much easier and consistent. Semi autos automatically regulate the activity of the water temperature for brewing and steaming as well as the activity of the built in electric water pump.

Semi autos are named as such because there is still a bit of work that you need to do in order to brew. Just like manual espresso machines, semi autos have a portafilter – an attachment that holds ground coffee during the brewing process. Before brewing, the portafilter will need to be filled with ground coffee. Then this coffee will need to be tamped, or compacted, in order for the coffee to fit properly and to create additional resistance during brewing. Then the portafilter is attached to the machine. To start the brewing process, you simply push the coffee brew switch causing the electric water pump to draw water from the boiler and force it under pressure through the portafilter and coffee grounds. When the proper amount of espresso has been brewed, just turn off the brew switch and you are done.

In the same family of semi automatic machines are automatic espresso machines. This term confuses most people because they may think automatic implies the machine does everything including grinding, tamping, and disposing of the used coffee grounds. This type of machine does exist, but is called a super automatic (you can read more about these machines below). An automatic is essentially the same as a semiautomatic except that it automatically controls the volume of water that is dispensed through the coffee grounds. As a matter of convenience you can choose among two to three programmable brewing buttons. The buttons can be programmed by you to tell the machine to run a certain amount of water though the coffee grounds in the portafilter, then automatically stop. Since it can take up to 30 seconds to brew two shots of espresso this automatic feature frees you to prepare other ingredients for your beverage while the machine is brewing the espresso. Many commercial machines use automatic systems such as this to give the drink better consistency and to allow the Barista to prepare other beverages in a timely fashion. However, all of the steps of preparing the coffee for brewing, including adding and tamping the coffee grounds, will still be the same as a semi automatic model.

Super Automatic Espresso Machines

Simply put, super automatic espresso and coffee centers are amazing. Yes, they make espresso, café crème, and they are capable of making all coffee house drinks like lattes, mochas, cappuccino and more. But most of the preparation for brewing is completed automatically by the machine – all at the press of a button.

A super automatic machine has all of the same basic components that semi and automatic espresso machines like an electric water pump, boiler, water reservoir, steam wand, and a variety of dials and switches. What makes super automatics different is that they have an automated internal brewing system and a high-quality burr coffee grinder built in. All of these components come together with the help of an onboard computer to quickly and effortlessly produce perfect and consistent espresso without the mess and guesswork that one might experience with either a semi or automatic espresso machine.

When you push the coffee brew button, coffee beans held inside the machine will be ground and placed into the internal brewing system. The pump will automatically start the flow of hot water through the coffee grounds and then result in espresso being automatically dispensed into your cup from spouts located on the front of the machine. Immediately after brewing has finished, the internal brewing system will take the used coffee grounds and discard them into the onboard waist box for later disposal. From start to finish you can have a fresh cup of espresso or café crème in 30 seconds.

One shining ability of super automatic espresso machines and the reason they are dubbed “coffee centers” as well, is that they can produce a coffee beverage called café crème. This coffee is brewed in the same manner as espresso. However, where espresso is brewed relatively slow (about 15-20 seconds for 1.5 ounces), cafe crème is brewed at a faster rate. Espresso brews slower because the coffee grounds are required to be very fine, which restricts the water flow through the grounds. This helps give espresso its intense flavor and strength. For café crème, simply make a small adjustment to the coffee grinder to make the coffee grounds coarser. This in turn will allow the water to flow more freely through the coffee grounds as required. The result is a wonderfully aromatic and flavor-rich coffee that is a smooth replacement for the same-old drip coffee.

As you can see, espresso machines can be rather diverse despite their similarities. Figuring out which type will suit you best will mainly come down to how involved in the brewing process you’d like to be. If you’re a really hands-on person, a manual or semi automatic machine is probably for you. If you’re into quick and easy, a super automatic is something you should consider. But no matter which type you choose, you can be sure that your machine will be perfectly equipped to make those espresso drinks you’ve been craving.

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