Lower pressure brewing

#1: Post by **Jepy** » December 26th, 2007, 3:25 am

A while back I was at a pretty well known coffee bar in San Francisco doing some pressure readings, and found that their machine a LM Linea, was set for a pressure of 100 psi at the PF. I wasn't too surprised, but the Barista was. Anyway, I started playing around with lower pressures on some of my equipment, and found that I really like the lower (sub 7 bars)pressures far more than the standard 9 bar.
I haven't played with many blends, but at least 3 commercial ones that I have tried seem quite nice. Anyone else experimented with these pressures?
I also went to another location of the above cafe, and found their GB5 was set a little over a bar higher with the same blend. The lower one is the shop I go to, just seems better to me.
If interested there's a clip of how I set up a current blend I'm using with a pressure profile here:

Again though, just trying to see if anyone else has seen this as plus in there experiments

December 26th, 2007, 12:59 pm

lots of tiger flecking in the cup, the shot looked pretty good.

on a side note, i do have to comment on how abnormally ristretto that shot was for a double basket, it appears to be < 1oz?

how do the two taste profiles compare, 7bar vs standard 9ish bar?

#3: Post by **TimEggers** » December 26th, 2007, 1:39 pm

I bet the low volume is more attributed to the lower pressure. In other wards a 6-7bar normale may be 1 ounce rather the typical 2-ounces we often hear about.

December 26th, 2007, 2:20 pm

i do have to comment on how abnormally ristretto that shot was for a double basket, it appears to be < 1oz?

This cup is a very wide "v" shape, so as it a short ristretto, it's probably at an ounce.

how do the two taste profiles compare, 7bar vs standard 9ish bar?

What I find is that the mouthfeel seems heavier, and flavor is noticeably smoother, seems the higher you go, the sharper to the cup becomes. I've tried dark and lighter roasts, and the effects going lower are similar. I'm going to try this on a standard rotary pump Synesso later this week. I hope some of you will get to experiment as well.

I bet the low volume is more attributed to the lower pressure.

On this particular profile, the lower amount is more attributed to the pressure drop after the initial ramp up. You could adjust all this through grind/tamp I suppose

#5: Post by HB » December 26th, 2007, 10:41 pm

Jepy wrote: I haven't played with many blends, but at least 3 commercial ones that I have tried seem quite nice. Anyone else experimented with these pressures?

I haven't tried it on a pump machine, but have pull lots of "low brew pressure" on home spring lever machines (Elektra Microcasa a Leva, Ponte Vecchio Lusso). Their starting pressure of ~6 bar and they finish at around 4 bar. They pull a good shot. I wish that I had the gear to do programmable pressure profiles, e.g., 9 bar flat versus 6 bar flat versus 9 bar declining to 6 bar versus 6 bar declining to 4 bar. Greg and Andy have wrote about it: