I think most of us have by now come to accept that the doctrine of the need to present water to the espresso puck at a constant pressure has proven itself to be bogus
As we see in a spring lever espresso machine, the pressure reduces as the extraction progresses. This ensures that as the coffee becomes ‘poorer’ (as the desirable elements are extracted out) the pressure is reduced to protect against extracting the undesirable elements within the coffee
Given the relationship between temperature and pressure, I can’t help but wonder if the current mantra of ‘constant water temperature’ is also balls
Whilst it is clear that optimum espresso needs water to be presented in a fairly tight temperature range, I am increasing of the view that better results are achieved if the water temperature drops as the extraction progresses
Again, this is what happens within a lever group
Im not saying that water temperature doesn’t need to held within a fairly tight range, but I don’t accept that it should be held at a constant throughout the shot
If constant pressure and temperature were a prerequisite for exceptional espresso then lever machines would not be capable of making exceptional espresso. We know this isn’t true