On this blog, I always try and write about issues in speciality coffee in a way that your everyday, engaged coffee drinker gets. I want these things to excite them as much as they excite me. Partly that’s to do with my writing, but mostly it’s to do with what I write about. The following post may be boring to many, but I think it’s important. I call it a dummy’s guide, not because it is for dummies, but because it’s aimed at people who don’t use espresso machines regularly. Like myself. This is the product of secondary research rather than my own experience.
So, why is pressure profiling ‘exciting’? When you pull an espresso, water is pumped through at a certain pressure, determined by how much force is exerted to push the water through the coffee. This pressure is typically around 9 bars, and this will pull you a perfectly acceptable espresso. But, consider this, if water is allowed to go through at a slower pace, will that change the flavour? It works on the same principle as leaving your cafetiere/aeropress brewing for longer. Though of course just letting the water trickle down has its own disadvantages.
Pressure profiling allows you to control this factor. In particular, pressure profiling allows you to alter the beginning and end of the extraction to give an even flavour. In the middle, particularly when the coffee is still relatively flavourful, you want the pressure to be high. This allows for the best quality flavour to come through. The end of the extraction can then be levelled out so that whatever flavour left in the coffee is drawn out slowly and not given too much prominence. By the end of the extraction most of the good flavour has gone.
Of course, that’s just one type of journey profiling allows. I was shown a whole set of graphs of how pressure changed over time, and what impact this would have on the taste of the espresso I was drinking. There is debate over whether profiling can actually change that much about the flavour. This is compounded by it being notoriously difficult to test. A thought for the barista, sitting experimenting with espresso, not sure if the flavour has changed because of the dose amount, the temperature of the water, the coarseness of the grind, environmental factors OR the pressure profile. And then there’s tastebud fatigue on top of all that.
How is the pressure controlled? More and more espresso machines are being built with pressure profiling as a feature. Some of this is manual, and controlled with levers, and others are automatic, and controlled electronically.
Another accessible guide to profiling can be found here. If you want to read more on this fascinating subject, James Hoffman’s complex but comprehensive thoughts can be found here (basic) and here (not basic).