I trying to find some data on lever machine pressures, anyone know where I can get this? I'm wondering because on my prototype machine which isn't a lever, but uses pulse-less pressure delivery, I'm getting really good shots at lower pressures. I'm using larger, more accurate gauges that read in psi. Some of the best tasting shots are coming out at as low as 103 - 108 psi (7.1 -7.4 bars). All these are slow ramp to full pressure, usually about 10 to 12 seconds, also gradual ramp down at end with a total shot time of around 40 seconds.

I have a short video of standard, and bottomless if interested:
http://homepage.mac.com/jepy/.Movies/Sidebyside1.mov

I'm curious to see if anyone has seen these pressures working.......

Is that the same coffee, amount of coffee, grind & pressure in both videos?
If so, what a difference in crema!(especially color!)

I've got a gauge on my lever La Peppina, and without any assistance, it brews from 6 bar (start), down to 3 bar (finish).
If I push the lever in assistance, I can watch the gauge and put the pressure wherever I want.

I haven't done a great deal of testing, but I do know I get the best looking and most persistent crema in the 8-9 bar range.
I've also found I can delay blonding if I raise the pressure near the end. This does not always help the taste though

One of the downsides of doing anything with La Peppina is that if you really stuff the basket you can get a whopping 14g into it.

Also, I get an error when I try to watch your videos... Quicktime says it's missing something. This is on a PC/Firefox. Quicktime works for me otherwise.


ciao

lino

Jepy, on your machine can you try out different pressure profiles? Have you done any more experimentation with it?

Henry

j7on wrote:Is that the same coffee, amount of coffee, grind & pressure in both videos?
If so, what a difference in crema!(especially color!)

Same for both.

Thanks Lino for your input on your Peppina, sorry for the videos being sometimes difficult to see.


Henry, I have tried many different profiles. In full manual mode, I can vary it all over the place. In semi automatic mode it can be set to a profile and repeat it. I seem to always go back to the lower pressures, as I like the smoother flavor a little more-the experimenting never ends.

Here's a video(6" dia.gauge view) of a semi auto profile that I really like for this particular coffee(Paradise Roasters Espresso Classico)


http://homepage.mac.com/jepy/.Movies/profile%201.mov

I too have played with Peppi lever assists, although without a pressure gauge. My finding are in line with Lino's, the classic 9 bar (as far as I can calculate based on the pressure I'm adding) is best for crema, but the bitterness increases sharply if one maintains this. I've compromised by helping the lever early, easing off at the end, and removing the cup before too much blonding sets in. This is basically an extraction which starts at 9 bar and ends at 3.

While doing this, I noticed something. I now manipulate the lever to hold a fairly constant flow rate. As everyone knows, the flow tends to increase on a motor, constant pressure, espresso machines as the shot ends. I'm hazarding a guess that a good place to start with pressure profiles is one that results in constant flow. Obviously, this has the minor justification of maintaining the same extraction rate across the shot. But more importantly, it's an easy profile to verify optically; and finally, if someone with good measuring equipment can publish the pressure curve that results in a constant flow, we'll learn more about how espresso extracts in real time.