mdmvrockford wrote:I have had this discussion in person with some senior HB.com members who said basically as such (i.e. not worth measuring).
I think its well known, and healthy for the community, that senior HB members disagree with other. My personal opinion, which is also no surprise, is that pressure profiling is worth measuring, and that having a good grasp of it will definitely improve your espresso experience. With the right skill / tools you can repeatably modulate the flavor of a cup to your preference (within the potential of the coffee of course). I often find that tweaking the pressure profile can change a good shot into a great shot. I understand that the same could be said about tweaking other variables as well, but with the exception of flow profiling, pressure profiling has the most amount of flexibility for how it is administered across different phases of the extraction.
Such is why I believe it is a useful tool, and one of my tools of choice for dialing in coffee. It may not be as useful as a tool for others whose equipment favors modifying other variables instead. Even so, modifying preinfusion time or overall shot pressure is often within the realm of most machines, and I would consider those both to be within the "pressure profiling" realm.
As far as general profile recipes go, there are a few generalizations that can be made, but there are always coffees and regions that will be exceptions.
Here are some general guidelines that I follow:
Longer preinfusion times will reduce acidity.
Higher preinfusion pressure will increase body / mouthfeel.
A declining pressure profile can increase sweetness.
As far as regions go, I have found that a sharp decline in pressure after about 2/3 the way through the shot creates a lot of sweetness for lighter roasted guats and colombias.
A slow ramp up of pressure will cause a faster overall flow (i.e. allow you to grind finer if you wish)
For dark roasts and Italian roasts I like to peak at 7 bar.
For lighter roasts I like to peak at 8 bar.
For light roasts on the Cremina I often preinfuse for 10 to 12 seconds, push on the lever and hold at 3 bar for another 3 seconds or so, then ramp to my desired max pressure. I hold that pressure until it starts dripping fast enough to get a flow, then I try to keep the flow constant at a rate where I will arrive at 3 bar when I hit the shot's target weight.