The modern day espresso maker has a noble lineage. In 1938, an Italian café owner by the name of Achilles Gaggia invented a machine to make espresso. It used a hand-operated piston to drive heated water through finely ground coffee under high pressure. That first espresso maker required both skill and strength to operate properly, but once one learned the knack of it, it could turn out flavorful espresso that was sweet, thick and rich with crema every single time.
These days the piston-driven espresso maker is a collector’s item, more often a display piece than a practical workhorse, while there are a few exceptions. Its place has been taken by the pump-driven espresso maker, whether the pump is operated by pushing a button, or switches on automatically when everything is right for extracting perfect espresso. The modern day espresso maker still depends on the same principles as Gaggia’s original invention, though, and the basic anatomy of the espresso machine remains the same.
These days the piston-driven espresso maker is a collector’s item, more often a display piece than a practical workhorse, while there are a few exceptions. Its place has been taken by the pump-driven espresso maker, whether the pump is operated by pushing a button, or switches on automatically when everything is right for extracting perfect espresso. The modern day espresso maker still depends on the same principles as Gaggia’s original invention, though, and the basic anatomy of the espresso machine remains the same.
The Main Parts of an Espresso Maker
And why each is important in making excellent espresso
And why each is important in making excellent espresso
Boiler
The boiler heats the water both for making espresso and for creating steam to froth milk and other drinks. In a high end espresso maker, there may be two boilers – one for each function.
The distinction between a single boiler machine and a twin boiler machine is a vital one, because the difference in temperature need for each task is significant. Espresso should be extracted at temperatures between 194 and 198 degrees Fahrenheit – but a good head of steam requires temperatures above boiling – 212 degrees Fahrenheit. In a single boiler machine, the boiler needs time to cool between shots if the steamer is used, or to heat up for steaming and delivering hot water. In a twin boiler, each boiler maintains water at the correct temperature for the task, and the barista can immediately extract another shot of espresso, or even perform both tasks simultaneously.
Brew Group
The brew group is the business end of the espresso maker. It holds the coffee, allows the water to pass through it while maintaining the proper temperature, and dispense the extracted coffee into the cup. Because maintaining the temperature is so important in the flavor of the espresso, the material of which the brew group is made is also very important. Professional machines use chrome plated marine brass for all of these parts because of its superior heat-retaining properties. Many consumer machines also use solid brass brew groups, but the least expensive machines may use steel or another metal with less heat retention. The parts of the brew group are:
- Grouphead
The grouphead is located on the bottom of the machine. It contains the locking connector for the portafilter and plays a part in maintaining the proper temperature. It must be sturdy enough to hold the portafilter firmly under very high pressure.
- Portafilter
The portafilter is exactly what it sounds like – a portable filter. It usually looks like a cup with a long handle and one or two spouts at the bottom. The filter basket fits inside it snugly, and it locks into the grouphead securely. The best portafilters are made of solid, chrome plated brass. On most commercial machines, the portafilter has two spouts, but single spouts are also common.
Portafilters are available in different sizes to accommodate enough coffee for a single or double shot of espresso, or to accommodate a coffee pod. Many of the newer machines can accommodate a coffee pod without an adapter, but older machines may need a pod adapter in order to use coffee pods.
- Filter Basket
The filter basket fits into the portafilter and holds the ground coffee. Like the other parts of the brew group, they are usually made of brass in professional machines for heat retention purposes, but may be made of steel or aluminum in less expensive machines. The filter basket is an essential part of the extraction process in an espresso maker, and its weight and the size of the holes can affect the quality of the espresso made with it.
- Dispersion Screen (aka shower screen)
The dispersion screen, also known as a ‘shower screen’ fits into the grouphead above the portafilter. It consists of a metal disc with tiny holes over its entire surface. The dispersion screen ensures that all of the coffee in the filter basket is wet evenly and at the same time with hot water.
Pump
The proper making of espresso requires a pump to force water through the coffee at a pressure of about 9 bars. While there are steam powered ‘espresso machines’, most coffee experts will tell you that steam machines require far too high a temperature to reach the proper pressure. There are two types of pumps used in espresso machines. The type of pump that’s most commonly found in a home espresso maker is a vibratory pump. An espresso maker without a pump is more properly termed a moka pot.
Thermostat/Thermometer
Perfect espresso requires temperatures within a very narrow range – about 6 degrees variation. In an automatic or semi-automatic espresso maker, the thermostat serves the purpose of switching on the pump when the water in the boiler reaches that precise temperature. In an espresso maker that is activated by pressing a button or using a lever, the thermostat will turn a signal on or off to tell you that the machine is ready to pull off a shot. It will also let you know when water is at the right temperature for steaming.
Steam Valve
The steam valve (and steam wand) allow you to draw off steam and/or hot water during or after brewing. In part, can help regulate the temperature of the water in some low end machines. In fact, the Rancilio Silvia, one of the most popular and highly regarded machines, nearly requires this to ensure perfect temperature control.
The boiler heats the water both for making espresso and for creating steam to froth milk and other drinks. In a high end espresso maker, there may be two boilers – one for each function.
The distinction between a single boiler machine and a twin boiler machine is a vital one, because the difference in temperature need for each task is significant. Espresso should be extracted at temperatures between 194 and 198 degrees Fahrenheit – but a good head of steam requires temperatures above boiling – 212 degrees Fahrenheit. In a single boiler machine, the boiler needs time to cool between shots if the steamer is used, or to heat up for steaming and delivering hot water. In a twin boiler, each boiler maintains water at the correct temperature for the task, and the barista can immediately extract another shot of espresso, or even perform both tasks simultaneously.
Brew Group
The brew group is the business end of the espresso maker. It holds the coffee, allows the water to pass through it while maintaining the proper temperature, and dispense the extracted coffee into the cup. Because maintaining the temperature is so important in the flavor of the espresso, the material of which the brew group is made is also very important. Professional machines use chrome plated marine brass for all of these parts because of its superior heat-retaining properties. Many consumer machines also use solid brass brew groups, but the least expensive machines may use steel or another metal with less heat retention. The parts of the brew group are:
- Grouphead
The grouphead is located on the bottom of the machine. It contains the locking connector for the portafilter and plays a part in maintaining the proper temperature. It must be sturdy enough to hold the portafilter firmly under very high pressure.
- Portafilter
The portafilter is exactly what it sounds like – a portable filter. It usually looks like a cup with a long handle and one or two spouts at the bottom. The filter basket fits inside it snugly, and it locks into the grouphead securely. The best portafilters are made of solid, chrome plated brass. On most commercial machines, the portafilter has two spouts, but single spouts are also common.
Portafilters are available in different sizes to accommodate enough coffee for a single or double shot of espresso, or to accommodate a coffee pod. Many of the newer machines can accommodate a coffee pod without an adapter, but older machines may need a pod adapter in order to use coffee pods.
- Filter Basket
The filter basket fits into the portafilter and holds the ground coffee. Like the other parts of the brew group, they are usually made of brass in professional machines for heat retention purposes, but may be made of steel or aluminum in less expensive machines. The filter basket is an essential part of the extraction process in an espresso maker, and its weight and the size of the holes can affect the quality of the espresso made with it.
- Dispersion Screen (aka shower screen)
The dispersion screen, also known as a ‘shower screen’ fits into the grouphead above the portafilter. It consists of a metal disc with tiny holes over its entire surface. The dispersion screen ensures that all of the coffee in the filter basket is wet evenly and at the same time with hot water.
Pump
The proper making of espresso requires a pump to force water through the coffee at a pressure of about 9 bars. While there are steam powered ‘espresso machines’, most coffee experts will tell you that steam machines require far too high a temperature to reach the proper pressure. There are two types of pumps used in espresso machines. The type of pump that’s most commonly found in a home espresso maker is a vibratory pump. An espresso maker without a pump is more properly termed a moka pot.
Thermostat/Thermometer
Perfect espresso requires temperatures within a very narrow range – about 6 degrees variation. In an automatic or semi-automatic espresso maker, the thermostat serves the purpose of switching on the pump when the water in the boiler reaches that precise temperature. In an espresso maker that is activated by pressing a button or using a lever, the thermostat will turn a signal on or off to tell you that the machine is ready to pull off a shot. It will also let you know when water is at the right temperature for steaming.
Steam Valve
The steam valve (and steam wand) allow you to draw off steam and/or hot water during or after brewing. In part, can help regulate the temperature of the water in some low end machines. In fact, the Rancilio Silvia, one of the most popular and highly regarded machines, nearly requires this to ensure perfect temperature control.
