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How does Pressure Affect the Intensity of Coffee?

16 June 2021
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There are many factors that contribute to the quality of your coffee and pressure is a key aspect. Here’s what you should know about managing pressure to get your best brew.

When it comes to coffee, the ‘rules’ are not set in stone. While it’s important to learn the basics, it’s always up to you to make your coffee the way you want it. But what is pressure when it comes to coffee preparation?

In short, it’s a combination of the amount of force the water is pushed into your puck and the resistance produced by the coffee puck. The water pressure is what pulls the oils from the coffee grounds to create the desired taste profile. Together, these will determine how the coffee is extracted from the grounds and how it will eventually taste.

It Starts with a Good Tamp

a person holding a porta filter filled with coffee grounds
Aim to make your puck as dense as possible to maximise the extraction of flavours. Photo from Noora AlHammadi.

A good tamp is one that has good resistance to the water that will be pushed through it. It should allow the water to be distributed evenly and give it enough time to saturate and extract the flavours from the grounds. An even extraction results in higher extraction of flavours which usually gives you more sweetness.

If your coffee grounds are loose, lumpy, or uneven, it may lead to uneven extraction and less than ideal outcomes — the water will just flow through the gaps quickly without extracting the flavours, resulting in a watery and flavourless brew. Under-extracted coffee usually has less flavour and tastes more acidic giving it a sour profile while over extraction can make it bitter and ashy.

Key takeaway: The secret of a great crema extraction and balanced cup of coffee begins with a good tamp. Here’s where you can get one.

Packing the Perfect Puck

a person levelling coffee grounds on a portafilter
Don’t forget to wipe off excess grounds before inserting your portafilter into the machine. Photo from Thome Holmes.

To facilitate optimum extraction, the goal is to have a compact, uniform surface area. To achieve this, start by making sure your coffee beans are finely ground and the grounds are even before you start putting pressure on it — you can easily do this by tapping your portafilter against your hand or a tamping mat.

Once that’s done, hold the tamper like you would a doorknob then apply force straight down.
While a twisting motion is recommended as you pull up your tamper (known as “polishing”), hold back from twisting the tamper while you are pressing down as this might disturb the packed coffee.

Pro tip: Use your body weight and not just your wrist strength to apply pressure to avoid spraining your wrist.

It’s important to note that while there is a range of recommended amount of pressure to apply to the puck, it is not as important as how well your puck is packed. Applying more pressure will not necessarily give better output and vice versa, if the other variables are not in their correct form.

Before you insert your portafilter into your coffee machine, take one last look to check there are no gaps or loose spots in your coffee grounds. It’ll also be good to wipe off any excess grounds on the edges of the portafilter to protect your portafilter gasket and reduce the need for machine maintenance.

Managing and Experimenting with Pressure

a person holding a cup of coffee in front of a coffee machine
The De’Longhi La Specialista has numerous options for personalisation but also has one-touch recipes for a fuss-free operation. Photo from De’Longhi.

Pump espresso machines usually come with different intensities of pressure like the De’Longhi La Specialista which offers up to 19 bar pump pressure. Most machines brew coffee at nine bars which takes about 25 to 30 seconds to pull a shot of espresso.

If you’re unsure, the rule of thumb is: lesser pressure means slower flow while higher pressure has faster flow. Your coffee needs time to be extracted so setting a higher pressure may not give the best results. However, this also depends on the grind size, water temperature, the type of roast you are using, and your personal taste preference. A longer brew time may also result in a more acidic coffee as more acid is extracted the longer your grounds stay in water.

The right pressure also allows you to produce crema, the flavourful, aromatic, golden froth that rests on top of a freshly brewed espresso which is usually an indication of a good espresso. You’ll normally get this using seven to nine bars of pressure.

If you’re just starting out recreating your favourite coffeehouse experience, opt for a coffee machine that allows you to adjust grind size, brewing duration, coffee quantity, and if you like your coffee with milk, milk textures. This will help you experiment and explore different coffee recipes to find out which works best for you!

This article features De’Longhi La Specialista

This article features Professional Barista Coffee Tamper

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