Can any of you guys who have a pressure-profiling machine tell me:-
1)What differences in a shot can be liberated by changing the profile from a typical 9bar extraction?
2)What changes (if any) do you need to make to the grind when you make a conscious decision to make a change in the pressure profile?

Cheers,
Paolo

I only fit in your category by a slight margin, but I can pressure profile both pre infusion and spring compression resistance during the extraction. The resulting grinds? Fine as powder if I want, and I can dose down and find true flavor separation by slowing the flow thru the puck. Normally, the Strega likes larger coarser ground doses, but by tweaking the pre-infusion pressure, I can flip this quite easily and get even better extractions.

I use slow ramp up and pre-infusion which allows a finer grind. My machine (a flow profiler) usually reduces pressure near the end of the shot in order to keep flow constant. I'm not into trying to describe taste so I'll just say "better".

Similar, but my machine is a true pressure profiler.

I will use a 2 bar 10s preinfusion, slowly ramping to 11 bar, 7 s:: 9 bar, 8s:: 8 bar, 6s:: finally 6 bar, 5s.

to answer the OP second question 1st. The grind I need to use would choke a normal 9 bar machine, but runs fine with the profiling. lowering the pressure in stages during the shot allows the extraction to continue without losing puck integrity and minimises the harsher flavours high pressures would bring out later in the shot. Further changes in the profile don't really affect grind, as much as the long preinfusion does and that initial ramp speed up to high pressure.

The differences in the shot are flavour plus, with such a fine grind and a better extraction you get more, lots more. It's like turning up the gain, but without getting extra noise (noise being the undesirable flavours).

Changing pump acceleration for a quicker ramp to each pressure can slightly affect grind level....but I'm still experimenting.

DaveC wrote:Similar, but my machine is a true pressure profiler.

I will use a 2 bar 10s preinfusion, slowly ramping to 11 bar, 7 s:: 9 bar, 8s:: 8 bar, 6s:: finally 6 bar, 5s.

to answer the OP second question 1st. The grind I need to use would choke a normal 9 bar machine, but runs fine with the profiling. lowering the pressure in stages during the shot allows the extraction to continue without losing puck integrity and minimises the harsher flavours high pressures would bring out later in the shot. Further changes in the profile don't really affect grind, as much as the long preinfusion does and that initial ramp speed up to high pressure.

The differences in the shot are flavour plus, with such a fine grind and a better extraction you get more, lots more. It's like turning up the gain, but without getting extra noise (noise being the undesirable flavours).


Changing pump acceleration for a quicker ramp to each pressure can slightly affect grind level....but I'm still experimenting.

So does that mean that for every different profile that is used, the grinder has to be dialled-in to suit that particular profile?

Paolo wrote:So does that mean that for every different profile that is used, the grinder has to be dialled-in to suit that particular profile?

It depends on the profile, not always, but sometimes...yes. As I have pump acceleration parameters to play with as well, which indirectly affects flow and ramp rate, this can further complicate things. As I use my machine more i realise I will probably have 2 or 3 favourite profiles and a preferred level of pump acceleration that suits my taste. Others with the same machine when they start shipping in few weeks, may well prefer a different setup to me.

The difference with a pump that adjusts pressure and is mains pressure independent even when plumbed in, means I can explore profiles beyond the capabilities of most other machines.

I covered this sort of stuff in my review of the prototype and what's to come on the production machines.