Espresso machines have greatly revolutionized coffee brewing in the 21st century. Modern technology has seen to the rise of digital espresso machines sending many baristas packing.Espresso machines rely on the pressure concept to brew coffee – the machine forces pressurized water through a puck’ of finely ground coffee to produce a highly concentrated and thick coffee – espresso. The first machine dates back to 1884 built by Angelo Moriondo, an Italian from Turin. Since then, the machine has undergone improvements to meet the changing times and client preferences.
Espresso machines are driven by a variety of systems – piston driven; air-pump-driven, steam driven and pump driven are some of the common machines. They may either be manual or automatic. This article will focus on the parts, drive mechanisms and finally automation of the espresso machines.
A typical espresso machine consists of a group head, a portafilter, and a steam wand.
Group head – acts as the receiver for the removable portafilter/group handle. Typical espresso machines will constitute of a single group head. More sophisticated machines especially the professional machines can hold up to seven heads. The group head hosts a shower which distributes the pressurized water evenly across the puck’ to attain a uniform cross-sectional stream.
Portafilter/group handle – fixed to the group head in the semi-automatic as well as the piston-driven machines. The handle is responsible for holding the puck of finely ground coffee beans. Usually made from brass for efficient heat retention and attached to a plastic/wooden handle for safety purposes. The portafilter directs the high-pressurized steam through the puck. Various portafilter are available with the bottomless portafilter being the most common among baristas – in analyzing coffee pack quality and evenness.
Steam Driven Espresso Machines.They were as a matter of fact the first espresso machines in history. These machines operate by forcing pressurized water through coffee mainly as pressure or steam. The design requires no moving parts and is therefore largely used among low-cost consumer machines.
Piston – Driven Espresso Machines
The design incorporates a level which sends pressurized hot water through the coffee grinds. The machines required a long handle to yield a single shot and the art was therefore nicknamed pulling a shot’.The design is used in two types of lever machines –
• The manual piston – the operator directly pushes the steamed water through the puck.• Spring-piston design – the operator tensions a spring which in turn delivers the pressure for the espresso.
Pump-Driven Espresso Machines
Currently the most common espresso machine especially in espresso bars. A motor-driven pump is used in place of the manual force. The machine, however, requires a separate source of cold water (tank or gallon).The machine has a range of variants of home machine options including:
• The single boilers – requires a single boiler since they are only capable of brewing. Offers other variants among them the Single Boiler, Dual Use, and the Heat Exchanger.• Dual Boilers – they require that water is boiled in a separate chamber and, therefore, requires two separate boilers.
Air-Pump Driven Espresso Machines
They use compressed air to force the pressurized water through the puck of finely ground coffee beans. The hot water is manually added from a thermos flask or a kettle. The compressed air is generated from N2 and CO2 cartridges or from a hand pump. These machines are smaller and lighter for maximum portability.
Espresso Machine Automation
Most of the modern machines are automatic – they consist of pumps, valves, grinders and sensors to mechanize coffee brewing. There are four categories of automation:
• Automatic – such machines automate the brewed volume by adding an in-line flow meter to the grouped. The pump turns off immediately the programmed amount passes through the meter. Camping and grinding are also done manually.
• Semi – Automatic – they utilize a pump in place of the manual force for water delivery.
• Super-automatic — Automatically grinds coffee, tamps and extracts a single shot.The operator fills the bean hopper and connects the machine to a water reservoir. Other models contain an automated dispensing device and milk frothing devices. Commercial establishments in most cases use the semi-automatic machines. These machines are larger than consumer models producing espresso shots quicker than consumer models.
Stay tuned for the latest information updates on espresso machines. You may need to check the next article for a guide before purchasing.