Pre-infusion is the low-pressure soaking of the coffee bed before an espresso machine builds to its full 9 bar brew pressure. This settles the coffee puck, which can minimize channeling and improve shot consistency.
Video transcript below:
The A53 is a direct plumb only machine, which means it uses the passive pressure of the water line to accomplish pre-infusion. It simply opens the path to the group head by opening a solenoid. The exciting part is that it can be programmed to automatically pre-infuse for one to eight seconds. When you use either of the machine’s brew buttons this pre-infusion step will automatically occur, making consistent pre-infusion easy.
Let’s go ahead and program this machine to do 4 seconds of pre-infusion. First, we’ll enter the setting menu by pressing and holding the power button for about 10 seconds. To change the pre-infusion setting we’ll now press and hold the boiler button for about 5 seconds. Now you can see that all the numbered lights on the face of the machine have gone dark. This indicates that pre-infusion is set to “off.” By pressing the hot water button we can increase the duration of the pre-infusion by one second at a time. I’ll press it 4 times to set a 4-second pre-infusion. By pressing the power button again, we’ll save and exit the settings mode.
Now let’s pull a shot. As you can see, when I press the shot button we get a slow trickle of water for 4 seconds and then we hear the pump kick in.
Just for fun, we pulled shots with zero, three, five, and eight seconds of pre-infusion to give you a visual for how that impacts extraction. Around here, we generally use about 5 seconds of pre-infusion. It’s enough to ensure even extractions without having too much impact on the yield you’ll have when you stop your shot.
The convenience of being able to pull a shot with automated pre-infusion which stops at a specified volume is why this is our go-to recommendation for offices and small shops – and why it’s the machine we use in our offices!