What Is Pre-Infusion Espresso? Can Every Coffee Machine Do It?

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As an espresso enthusiast or just the one who is keen on coffees, you have probably been trying any practical technique to get the best of brewing. And on this research journey, you are likely to hear about the “pre-infusion” term at least once.

For better understanding, it would help to learn more about pre-infusion and how this technology can transform your espresso taste. Hence, we bring here a simplified definition as well as list everything needed for this process. 

So, what is pre-infusion espresso? Let’s get started with the basic things to know about it. 

What Is Pre-Infusion Espresso?

When it comes to espresso, pre-infusion is when water goes through the portafilter filled with ground coffee. Or you can view it as the coffee pre-soaking or blooming phase. In other words, it is the one right before the stage of extraction. 

Pre-infusion normally does not require too much water. You only need to use a sufficient amount to wet the ground coffee evenly in the portafilter. 

To put it simply, in the pre-infusion process, the machine takes a low pressure so that the coffee puck can expand and absorb water. But the temperature is often higher than the one applied for extraction. 

More Detailed Explanation

As for a typical espresso extracting process, the water pressure of 9 bars (equivalent to 130 psi) is normally needed. The espresso machine will use a pump and build up that pressure for more details. Consequently, the pump and the pressure force water through the espresso puck.

Traditionally, the espresso machine maintains the 130-psi pressure throughout the extraction. It means when you press the “Start,” then activate the pump until the cup catches the last coffee drops extracted from the machine. 

At first, an amount of low-pressure water flows into the portafilter gently when you let the machine start. The pressure at this time often goes around 1 and 5 bars. However, it is entirely normal. This flow of water then soaks the ground coffee to make it saturated. 

And this whole stage is undoubtedly the pre-infusion process. 

After completing the full water saturation, it is time to hit the 9 bars of water pressure. This water will activate the coffee extraction, and you will see the first coffee drops fall into the cup. 

The Necessity

To sum up, pre-infusion relates to the stage in which water gently soaks the ground in the portafilter right before the process of brewing pressure. In other words, it ensures even water absorption for the coffee. As a result, you can avoid the issue of channeling. 

Channeling

Without pre-infusion, how does the channeling occur?

This issue comes when the water only penetrates a small part of the grounds instead of spreading evenly through the puck. Consequently, it results in an over-extraction which causes the coffee flavor to become much bitter. Generally, the less evenly the water flows, the less consistent the extraction. 

When tested by a shot without pre-infusion, you will notice more possibilities of channeling than the one with pre-infusion. The water only finds a low-resistance path to flow through. At the same time, it tends to avoid nearby areas of the coffee puck. Hence, the water flow over-extracts the channel and leaves the surrounding under-extracted. 

For better understanding, the primary goal of pre-infusion is to help the water flow through the grounds evenly. Only this way, the entire coffee puck can get wet well before the machine starts extracting.  

Other factors

The concept related to pre-infusion holds a key in mitigating the problems which often occur while tamping. Also, several factors are contributing to the issue of channeling. Here is an example.

Sometimes, you may go wrong in collapsing and distributing the coffee grounds in the portafilter. The improper completion will leave some cracks and air pockets in the puck. 

Another case is that you press the coffee grounds unevenly. There will be one or more than two spots that are not as dense as the surrounding area in the puck. 

Then, when the water flow with the high pressure (9 bars, for example) hits the coffee, channeling occurs due to those issues. In practice, water is a kind of lazy thing. So, it tends to punch on the path of least resistance. 

In short, your coffee will, honestly, taste quite terrible with an “ugly” bitter flavor. 

How Does Pre-Infusion Process Work?

As we mentioned above, the water penetrates the entire coffee puck evenly. During the stage of pre-infusion, the grounds will expand after absorbing enough water. The below instruction will help you know more about it. 

The Process

Pre-infusion allows the coffee grounds to expand and compress each other. Thanks to this compression, all cracks and holes in the portafilter will disappear. Next, the water under the high pressure will flow into the puck, and no channeling occurs at all.

Unless the spout of water flows unevenly in the puck, it can absorb the coffee ground’s fantastic flavor and aroma. Thus, all amazing coffee extraction will drop into your cup. 

Thus, when the full force of the high-pressured water is driven through the puck, channeling won’t occur. The water is now forced to flow through the fused puck, thus evenly absorbing the flavors and aroma. The fewer errors you make during the process, the tastier the espresso will be. 

The Time Needed

Our answer depends on which espresso machine types are in use. Besides, the choice of a single shot or a double shot needs a different amount of time for pre-infusion. Hence, knowing about your coffee machine and how long the coffee grounds need to seep out the water spout. 

Typically, the ideal time for pre-infusion varies from 2 to 8 seconds only. And then, the machine will turn to the extraction. 

How To Do Pre-Infusion Espresso?

Before digging deeper into how to do pre-infusion, it would be better to know about the espresso-making process first.

How To Prepare An Espresso?

The standard espresso brewing process is not the same all the time. It depends much on the type of espresso machine in use. For instance, a modern automatic device can give comprehensive support after you press the “Start” button. By contrast, a manual-lever machine requires more steps for brewing.  

Regardless of the machine or you – a barista who will carry out all steps, here is the process. 

  • Stage 1: After you add coffee beans into the machine, its grinder will ground them in the form of powder. 
  • Stage 2: You use a metal basket in the portafilter to get that coffee ground. This portafilter clips the basket onto the group head of the machine. 
  • Stage 3: A tamp will help to expand and compress the coffee puck. 
  • Stage 4: The machine starts heating the water at 195°F to create the essential pressure of 9 bars. We suggest flushing some water onto the whole machine before attaching the portafilter. It is for preheating the group head. 
  • Stage 5: It is time to attach the portafilter to the group head and let the high-pressure water flow through the pick evenly. 
  • Stage 6: The extraction begins and takes around 25 and 30 seconds. 

When To Do Pre-Infuse?

The pre-infusion starts when the portafilter gets fixed into its place. And this process finishes right before the stage of extraction. However, it is not that every espresso machine can achieve the pre-infusion. 

As for the plum-in device, it can do the pipe pressure. But you need to open its lever way. This tip lets water flow through and soak the coffee puck at low pressure. After that, the machine will activate the brewing process. Additionally, the device featuring a water reservoir can do this function well. 

In theory, it is possible to achieve the pre-infusion with the automatic/semi-automatic machine. In other words, you only need to switch on the spout of water and then turn it off.

Can Your Espresso Machine Pre-Infuse?

For years, espresso machines have been launched with hundreds of new advanced features. For example, it is the extraction stage with the higher espresso quality. And the function of pre-infusion is surely not out of the trend. That said, not every espresso machine has it. 

If you are still confused about searching for a model with this dedicated functionality, we bring here several recommendations.

Nuova Simonelli Oscar II

Are you searching for an espresso machine that is affordable and available with numerous high-end features? If YES, we would like to recommend the Nuova Simonelli Oscar II. Surely, there are tons of things for you to love about this choice.

Firstly, this model comes as one of the most budget-friendly espresso machines. It has almost the same price as similar products on the market. In particular, despite the low price, you will not feel any sacrifice of money on its quality so far. 

Secondly, Nuova Simonelli Oscar II features a copper-made heat exchange boiler. Thanks to the antimicrobial nature, this part can do its work so well when handling both brewing and steaming at the same time. 

On top of all, the integrated cup warmer is an indispensable feature of this model. It helps you keep more than one mug as well as leave some space for storage. 

To sum up:

  • A semiautomatic machine with the timed dosing button
  • Pour-over plumbing method
  • One group
  • Convenient warming shelf for the cup on the top of the device
  • A copper-made heat exchange boiler for both brewing and steaming simultaneously
  • A push and pull the steaming trigger for your wrist protection from discomfort

La Pavoni Bar Star

In case you are keen on an espresso machine to work at a fast speed and an additional pre-infusion, do not ignore La Pavoni Bar Star. This model has a 2-group configuration. Despite that fact, you can pick the 3-group configuration since it is extremely good in speed.

By a combination of three groups along with a steam wand, the La Pavoni Bar Star has got more popularity among the masses. It means that two different baristas can work on this machine simultaneously. In other words, there will be more cups of coffee made at once to serve more customers. 

Additionally, we also consider La Pavoni Bar Star an energy-efficient model besides its convenient structure. On the machine, there is a power switch with four positions in total. They allow you to turn to the standby mode for hours off easily as a solution to reduce power consumption. 

To sum up:

  • An automatic machine 
  • Directly connecting plumbing method
  • Three groups
  • Convenient telescopic Side Handle to move the entire machine easily 
  • An anti-vacuuming valve to prevent milk from going back and clogging the steam wand 
  • A 4-position power switch for energy saving solution 
  • A manual dosing button

Victoria Arduino Eagle One

Eagle One comes as of the latest models created by the Victoria Arduino. In particular, the product can meet most requirements regarding advanced features and design which an experienced barista often expects.

As for the first look, the Victoria Arduino Eagle One is available in numerous colors. It means that you can pick from more than one option to give the right fit for your coffee space. 

Besides, the machine is available with both two and three-group models. This flexibility allows the users to customize the espresso output capacity. If you need to work with a high espresso volume, we suggest choosing three groups. On the other hand, two groups will be more suitable for an average amount. 

The most impressive point found in the Eagle One is the energy efficiency. By running on an optimal engine as well as a thermal energy recovery system, the machine tends to consume less energy. 

  • An automatic machine 
  • Directly connecting plumbing method
  • Two or three groups
  • A thermal energy recovery system to reduce the water amount needed
  • An optimal engine Optimization for the energy efficiency 
  • An ergonomic steam lever to ensure comfort for the barista while working 
  • Numerous color options

To Sum Up

So, what is pre-infusion espresso

As we mentioned above, there are a lot of things to learn about it. Without this stage, no one can ensure that your coffee cup will bring the best taste ever. 

With the definition as well as instruction above, hopefully, we can help you enjoy an amazing cup of espresso.

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Almost 20 years already spent committed to coffee and more than 3 years of experience as a barista at Starbucks. Madelyn Doyle graduated with a Bachelor’s Degree in Nutritional Science from the University of California and finished the Coffee Skills Program at the Specialty Coffee Association (SCA).