A Vibrant Rant About Machine Espresso

How Does Machine Espresso Work?

Machine espresso employs precise pressure and amazing filter technology to make the perfect cup of coffee. What exactly is it that makes it work?

Espresso is made by forcing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee, but the difference is in the pressure.

The Group Head

The group head is the portafilter that you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter before controlling the pressure of the extraction. There are several different types of group head each with its unique advantages and drawbacks. Some are designed to provide temperature stability while others are specifically designed to handle pre-infusion. Others are made to control the lever. Some come with a combination of both, such as the E61. This is a favorite among baristas due to the fact that it has multiple advantages in one package.

As you can see in the photo above, the group head has many notches in which you can place your portafilter and twist it by hand to lock it in. A gasket of rubber is situated inside the notches to help create a seal when you insert your portafilter. The notches permit precise placement of the portafilter. This is crucial to ensure a consistent extraction.

In addition to allowing you easily place your portafilter in, the group head is also responsible to maintain an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure the temperature is always right for extraction. It is important to note that even a tiny difference can make the difference between a decent and a excellent espresso.

The Pump

Motorized pumps in rotary espresso machines supply the nine atmospheric bar pressure required for espresso extraction. This differs from manually operated piston machines that employ levers. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger before it is shot through the ground coffee inside the group head.

Pumps tend to be cheaper and last longer than piston-driven machines. However, both kinds of machines can degrade due to overuse and inadequate cleaning. They also create mechanical complexity, which can result in costly prices for even the simplest models.

Some espresso coffee machine home machines espresso make use of steam pressure instead of a pump for brewing espresso. The downside is that the boiler that produces steam also raises the temperature of water until it reaches boiling and can result in over-extraction. Additionally these machines typically have to restore their pressure between cups, which requires time and energy.

Many espresso machines make use of either a vibration or rotary pump. A vibration model uses a vibrating disk to generate pressure, while a rotating model pushes hot water through the ground at a fast speed. Both types of machines are capable of producing excellent espresso, but rotary machines are quieter and more durable than vibration pumps.

The Boiler

The dual boiler espresso machine is the component that heats water to the optimal temperature to extract. The resulting steam is then transferred to the portafilter containing the ground espresso coffee, and is then pumped down into the cup. During this process the steam causes enough pressure to push the grounds of coffee through. This results in a layer of crema on top espresso machines. This is a hallmark of a good espresso machine sale.

There are three types of espresso makers. They differ in the type of pump they employ and how hot the brew is. There are a variety of ways to control the brew and the size of cup that can be produced by the machine.

The first espresso machines were steam type. The earliest espresso machines were steam types. This led to the coffee tasting burnt and bitter. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso maker is a semiautomatic machine with an electric pump. This is what people envision when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans on your own however the pump controls the flow of water and pressure. This is a perfect solution that combines human control with mechanised accuracy.

The Filter

Espresso machines usually have filters that separate the grounds of coffee from hot water. The filter is also an important component of the temperature control system since it helps prevent the machine from overheating.

A filter also improves flavor, as it permits the beans to flower for a longer period of time. This allows the beans to let their nuances out and provides an opportunity for a better extraction.

However, it is important to remember that even a good filter can result in a poor cup of coffee, because the quality of the beans and extraction are vital.

This is where the magic happens. It's what makes an espresso really taste great. The grouphead, sometimes referred to as the brew head, is the place where the portafilter (the thingy you put the ground coffee in) sits when you're making espresso.

Steam-driven espresso machines make use of hot water that is heated inside an airtight vessel to create steam. The steam then pushes hot water through grounds of coffee at high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. They are however limited for creating the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent years, espresso machines powered by a compressed air compressor have become increasingly popular. They use an air-compressor to push hot water through the ground, and are more mobile than electric steam-driven espresso machines.