Espresso Machines

Priced around $40.00 - $40,000.00 depending on features

The traditional Italian coffee beverage known as espresso is produced by an Espresso Machine. It was invented in 1901 and since then has had many variations in functionality.

There are, however, a few features that are commonly shared by most espresso machines. One common feature you will find is a metal filter basket that holds the coffee grounds. This is referred to as a “portafilter” or “group handle”. It is locked in place and located just under the group head's diffusion block.

A steam wand is another common feature. It is used to steam and froth milk for cappuccino and latte drinks.
Now let’s look at the various types of machines and how they function.

There are three basic types of  espresso machines:

• Steam System
• Piston System
• Pump System

Other less popular (but worth mentioning) machines:

• Air-pressure System
• Stove top System

Steam System

A steam style machine is based on a system that forces water through the coffee grounds using steam or steam pressure. This method was the basis for the first espresso machines.

A common boiler was attached to four group heads and multiple types of coffee were made at the same time. The steam driven concept is still used today in lower cost consumer machines. It is a basic design and not as complicated as the machines that contain moving parts.

Many people state that the lower end machines are more labor intense and produce a lower quality cup of espresso. This is mostly due to fact that these machines do not heat up as rapidly and are not as precise in delivery.

One selling point, besides the low price, is the fact that you can purchase an espresso / coffee brewer all-in-one. Saving space and well as saving money is a popular idea especially in this economic climate.

Piston System

The piston (lever) system was first introduced in Italy by Achille Gaggia around 1945. The main design utilizes a lever that is manually pumped. This pressurizes the hot water and forces it through the coffee grounds. This pumping method to produce an espresso shot is often called “pulling a shot” because the operator is actually pulling a long handle down to draw the shot of espresso.

Lever machines contain two categories; manual piston machines and spring piston machines. Manual piston machines have the operator manually push the water through the coffee grounds. With the spring piston machine, the operator will work to a tension spring. That tension is what delivers the pressure for the espresso and is usually 8 to 10 bar units.

Pump System

The piston system was improved upon with the pump system. This is the type of machine that you will commonly see in most commercial espresso bars. Unlike the piston machine that uses manual labor, this machine is operated by a motor. The  motor provides the pump action that forces water through the grounds for more efficient espresso brewing.

Some of the higher end consumer machines and most commercial machines are attached directly to plumbing allowing an endless supply of water. Lower end home machines have a built-in water reservoir that needs to be filled often; depending on coffee consumption.

Home pump espresso machines typically are designed using a single chamber. This chamber not only heats the water for brewing but it also boils the water for steaming/frothing the milk. Since the temperature for brewing coffee sometimes differs from the temperature required for the creating steam, this type of machine will need time to transition from one function to the other. This down time is not present in commercial and the top-of-the-line home models.

Commercial and top-of-the-line home espresso machines generally use a boiler chamber that has a single use only; and that is to make steam. This creates a much more accurate temperature that is on demand instead of having to wait.

Other less popular (but worth mentioning) machines:

Air-pressure System

Another machine worth mentioning is a hand-held little oddity called a handpresso.  This is a very small, high-pressure espresso machine that looks like a cross between an airbrush and a tire pump. You operate it by manually pumping air into an intermediate chamber.

Hot water is then poured into a small reservoir, which can contain just enough hot water for one cup of espresso coffee or about 45ml. Ground coffee or a coffee pod (depending on the model) is inserted on top of the water reservoir and a portafilter is screwed on the top of the water reservoir. The machine is then turned around and the pressure from the intermediate chamber is released into the water reservoir. The high pressure forces the water through the coffee pod (or fresh grounds) and into the cup, which is positioned underneath the device. After the espresso is expelled, the pressure is released from the water reservoir.

The advantages of the handpresso is that not only can you have a high quality cup of espresso using high pressure that produces crema, but you can take it anywhere hot water is available or bring a thermos! It is popular perfect hiking and camping.

Stove top System

Stove top espresso makers or Moka pots can produce coffee with an extraction ratio similar to that of conventional espresso machines. Commonly found in Italy, Spain and Portugal, they are referred to as a macchinetta, Italian for "little machine".

The basic operation starts by filling the bottom chamber with water. There is a funnel shaped metal filter that is then inserted. Coffee that is finely ground is added to the filter. Another metal filter fits on top of the first filter sealing the coffee grounds inside. The pot is then placed on the stove and the water is brought to a boil. This creates steam in the bottom section.  The gasket (or seal) safely allows pressure to build and flood the top chamber with the finished espresso.

It comes equipped with a safety valve just  in case the pressure gets too high. As long as the filters are clean, this should not be an issue.  Depending on the beans that you select, and the grind, Moka pots can create the same crema of conventional espresso machines.

Categories of Espresso Machines

Semi-automatic, automatic, and super automatic

Semi-automatic

Espresso machines are considered semi-automatic if the water is delivered by a pump, rather than having to use manual force.  Another criteria is that the unit contain a three way valve that functions to alleviate brew pressure in the basket.

Automatic

Espresso machines are considered automatic when an inline flow meter with the grouphead is added. This flow meter allows the programmed amount of water to flow through; then the pump is automatically turned off and the brew pressure released through the three-way solenoid valve.

Super-automatic

Espresso machines are considered automatic machines when they perform all phases of production. This would include automatically grinding the coffee beans, then tamping it, and finally extracting for that perfect prompt, hassle-free cup of coffee. Your only responsibility is to fill the bean hopper when needed and possibly fill the water reservoir (if the machine is not connected to a water line).

Additionally, these super-automatic models have an automated milk frothing and dispensing device that allows you to fill and froth within seconds.