Define: Pressure Profiling

19 02 2010

Note that given the current early adoption phase of pressure profiling technology, everybody is still learning what is possible, us included. We have, for the past year, extensively used and experimented with pressure profiling capable prototypes and modified espresso machines and thought it is time to “go on the record” with what we have learned.

What Pressure Profiling IS:

  • Provides the ability to vary and/or manipulate brewing pressure (between 0 and 9 bars, static or progressive) during the extraction process
  • An additional espresso preparation variable that, in itself, has a high degree of possible brewing parameters

What Pressure Profiling is NOT:

  • Necessarily a new machine
  • Necessarily going to make EVERY coffee taste good*
  • Capable of making bad coffee good
  • The Holy Grail

What Pressure Profiling DOES:

  • Allows you to change the “volume” (or “expression”) of different flavor components to effect the balance and body of the shot*
  • Tends to produce a rounder, softer espresso that highlights brightness, sweetness, and delicate notes to emerge from the body of the shot*

What Pressure Profiling REQUIRES:

  • A very attentive, well trained barista
  • Good palate
  • LOTS of experimentation to subject your coffee to various pressure profile curves to determine the best fit, as there is no right or wrong
  • Objective and careful reconsideration of classic espresso extraction parameters (e.g. dosage, preinfusion time, total dwell time, etc.) in conjunction with open mindedness*

*Experiments reveal that even the same pressure profile has dramatically different effects on different coffees. Some espressos do taste better when subjected to pressure profiling. Some don’t.

In summary, this post is only meant to put some thoughts on pressure profiling, given some of the questions out there. If anything, this hopes to serve to get more discussion (and experimentation) going to further espresso quality and appreciation.




18 responses

19 02 2010
nick cho

Best. blog. ever.

19 02 2010

inspirational, beat us to it, but will only push everyone to discuss and theorise more.

21 02 2010

This post is an excellent introduction to pressure profiling concepts, but one of the statements seems deceptive:

> What Pressure Profiling DOES:
> * Tends to produce a rounder, softer espresso that highlights brightness,
> sweetness, and delicate notes to emerge from the body of the shot*

You appear to echo the reaction that many tasters ascribe to ONE PARTICULAR PRESSURE PROFILE, the one designed to mimic a spring-lever machine: “prefusion period” + “rapid rise to full pressure” + “brief hold period” + “gradual decline to lower pressure.”

But there are an infinite number of possible pressure profiles, including gradually rising profiles and/or profiles with bumps and valleys. Considering our collective lack of experience with these, it is incorrect (IMO) to say that pressure profiling IN GENERAL produces a certain type of shot.

21 02 2010

The clarify on the “deceptive” statement: It points to the observation that the vast majority of shots pulled with a progressively dampened pressure ramp up (whether it be only a second or two, or a lot more) results in a rounder, softer taste IN COMPARISON to the same coffee pulled on a typical semi-auto machine (that is, once you find the ideal profile for that given coffee). Even if you try to use a LM Mechanical Paddle (or a Slayer, for that matter) like a semi-auto, the ramp up to full 9 bars would still be much “slower” than a real semi-auto and nonetheless result in reduced channeling.

While it is impossible to assign a certain type of characteristic to pressure profiling given the infinite number of possible pressure profile curves, we do feel that the statement made does reflect most of our experience and tastings. We are aware that there is still a lot to learn from pressure profiling and that’s why the statement begins with “tend” and ends with an *.

IMHO, due to the limitations of current pressure profiling machines, the focus has been more (comparatively) on the pressure ramp up, rather than the ramp down. No machines available today can truly reproduce the gradual pressure decline as on a lever machine, nor are they necessarily meant to. The advantage of pressure profiling is to allow the barista to work with infinite profiles, rather than to mimic an old machine (not that you couldn’t or shouldn’t). In fact, most shots we experimented with were not pulled with a profile like that of a lever machine.

21 02 2010

“Deceptive” was a poor word choice on my part. Sorry about that, I didn’t mean to imply that your were deliberately trying to deceive.

If I understand correctly, it appears that the majority of your experimentation has been focused on the initial ramp up to pressure. This is interesting, because most of the pressure profiling people I know seem to assume that a decent preinfusion is standard operating procedure, and they’ve focused more on a ramp DOWN in pressure through the middle and end portion of the extraction.

I still feel that your comment on “what pressure profiling DOES” doesn’t have much utility unless you specify (at least in general terms) the profile you are using.

22 02 2010

Very true, and that’s why in the coming months we’ll try to do series of experiments with a data logger and a transducer to map out the actual pressure profiles. This makes communicating much easier. More posts to come with actual data and results.

25 02 2010
Jason S

What about repeatability? Could profiles be stored and programed? While I love to think that we can train our baristas to take the same care and approach each shot with precision and passion. On a busy Saturday morning being able to set a profile and stick with it would help greatly with consistency. Or better yet be able to set profiles for coffees on a lab machine and load the programs onto wholesale customers machines.

1 03 2010

As of now, no variable pressure machines today can truly reproduce an exact profile shot after shot. It’s based on the control and consistency of the barista. When there’s a dozen customers waiting to order coffee on a busy day, that’s a problem for even the best barista. Therefore, a truly practical pressure profiling machine not only needs to have precise pressure control but also repeatability/consistency.

Strada will be able to “record” a desired profile based on a shot you’ve just pulled and replay it back indefinitely (like a macro on a computer) with a flick of the paddle. In the future, you will also have the ability to see the actual profile (time vs. pressure) and manipulate the graph on the computer and upload it back to the machine for playback.

11 03 2010
Jason S

This is awesome… and should hopefully will be available when my current equipment is fully depreciated.

18 03 2010

Will the Strada come in a consumer/one group version? For the ultimate home-espresso?

19 03 2010
coffee supreme

nice, sums up most everything we are finding on the Slayer as well. thanks.

19 03 2010
Pressure Profiling or Infusion « Coffee Supreme

[…] we have found can be funnily enough summed up here, I find it quite amusing linking to LM for this info but its good and basically how I feel about […]

31 03 2010

Sorry, no one group is planned but you can do plenty with the GS/3 MP.

3 04 2010

In my own feeble experiments with my GS/3 MP, I find that the same factors that require barista adjustment of the grind and dose (staling of beans, changes in ambient temperature and humidity, nocturnal visits of gremlins) require changes in pre- and post-infusion times. If I am correct, how does this square with the goal of programmable pressure profiling?

5 04 2010

All current and future MP machines are manual in nature, and hence the barista is in control of all variables to account for any changes in parameters.

In Strada, the machine will allow several pressure profiles to be programmed. The barista has the option of selecting from pre-programmed profiles. Alternatively, the barista can also manually pull a shot and, if it’s good, record that profile (much like macro in Excel).

So let’s say that an environmental factor has changed and it does necessitate a different pressure profile, the barista can simply manually pull shots to find a calibrated profile s/he likes (much like adjusting the grind). Then it’s just a matter of pressing a button to record that for later “replay”.

21 06 2010
La Marzocco Strada Is Your Barista’s New Wet Dream Machine | Gizmodo Australia

[…] with pressure is kind of like the new thing to doin coffeeland. The point of pressure profiling, as it’s called, is to pull different qualities out of espresso by manipulating the pressure […]

14 07 2010
Pressure points → St. Eutychus

[…] Pres­sure pro­fil­ing, man­ag­ing the pres­sure dur­ing the pulling of a shot of cof­fee, is “the next big thing“TM in spe­cialty cof­fee. Pres­sure is one of the vari­ables dur­ing the shot that until now has been restricted to mod­i­fy­ing your machine’s pump in order to have a par­tic­u­lar water pres­sure sup­plied through­out the shot. […]

25 02 2011
Slayer - Preinfusion? - Kaffee-Netz - Die Community rund ums Thema Kaffee

[…] Pretty simple. What you do with it is up to you. What we have found can be funnily enough summed up here, I find it strange linking to LM for this info but its good and basically how I feel about it at […]

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