Espresso Machine
The espresso machine is the mainstay of many cafes, coffee houses, restaurants, hotels and anywhere there is a desire for excellent coffee.
The espresso machine history dates back to 1822 with the first espresso machine.
The modern espresso machine was created by Gaggia in 1946.
There are 3 main types of espresso machine.
Steam Driven
The earliest espresso machines were the steam driven type which work by forcing water through the coffee grinds using steam pressure.
This technique is still used on some domestic espresso machine, as it requires no moving parts, so they can be produced at low cost.
The problem with steam driven machines is that there is possibilty that the steam can scald the coffee affecting the taste.
Piston / Lever Driven
The piston / lever driven espresso machine works by the barista pumping a lever which puts the water under pressure.
The water is then forced through the ground coffee producing the espresso.
This method is still popular today, however they tend to be more domestic machines than commercial.
Lever espresso machines were the first to produce espresso with a crema.
This crema was at first looked upon with mistrust but after trying most people agreed the taste was less and more enjoyable.
Today this crema is recognised as a sign of a good espresso.
Pump Driven
The pump driven espresso machine works on the same priniples as the lever machine, but uses a pump to create the water pressure.
This allows the espresso to be created without any effort from the barista.
Most modern commercial espresso machines work at the touch of a button, sending the correct amount of water, at the right temperature and pressure , through the coffee in the group head.
A Modern Automatic Espresso Machine
Making an espresso
To make an espresso you need to start by grinding 7-10 grams coffee beans finely.
This poured in to a group head which is a metal cup with tiny perforated holes to alow the water through.
The ground coffee should be tamped down with 5 pounds of pressure to form a puck shape.
Water heated to 90 °C (194 °F) is forced through the ground coffee at a minumun of 9 bar pressure, though higher is better 12-14 being ideal.
To make an ideal espresso this extraction time should be between 20-25 secs.