It was interesting that two coffees (use partly beans from same region) from two roasters, both came with the specific instruction of No PI. Which was a first for me.

1) SO: Ethiopia Guji 50% Hambela, 50% Tabe Burka
Recipe: 18.2g, 28sec, 38ml, 93C, ESP. No PI

2) Blend: Ethiopia Tabe Burke & Bristol Ondas natural
Recipe 21g, 22sec, 40g, 91-93C, no PI

Any thoughts on why this would be?

I use a robot and it would be convenient for the sake of consistency to ramp up to pressure over 5secs. 3 as a minimum.

The first bag I had dialed based on following the Espresso 101 method, but with 3sec ramp up. Have been impressed with that philosophy (especially after I cleaned my grinder and realised it had been blocked throwing things off)

Then I followed the recipe from the second bag. I was surprised with the speed of the shot. I dialed it in ok, got to the balanced and dull point. And cut the subsequent one off a few secs earlier to get the desired result (didn't want to up dose from 21g) but it gushes at the end and it's real hard to get consistent results - hence I haven't really bothered to try and fine tune. It's pretty good though to be fair.

So my thinking is ideally I can adopt ramp up to 7-8 bars over 5 secs as a standard, but I fear missing out by ignoring the specific instructions.

Why? The short answer is that the roasters pulled shots to their preferred taste within these parameters.

Based on the recipe for the blend, I'm assuming it was taken to a more traditional roast. And no PI (or a quick ramp to 6/7/8/9bar) in that case means less of the unpleasant bitterness that could come from an extended soak. I'm tempted to think the same for the SO, though the one or two Gujis that I've pulled have been light and came out better with a 1:3ish ratio and a healthy PI.

But you've mentioned a 5 sec. ramp up, which in my thinking, isn't so long that I would be concerned about missing their intended taste range. In other words, go for it, and see how it tastes. Play with it. The Robot is great for that kind of experimentation. And don't hesitate to ramp down in pressure toward the end of the shot to avoid some of the messiness.

I can't think of a reason to not pre-infuse other than to simplify things. How about asking the roaster for the rationale behind this recommendation?

Perhaps the roaster dialed in with an espresso machine that didn't support pre-infusion?

One of the coffees I routinely buy I pull (on a Robot) without any preinfusion. I mean, there is some time between zero pressure and 7-8 bar or whatever but it's on the order of 1-3 seconds. Pretty close to just bringing the hammer down.

I found that preinfusion only added bitterness to a coffee that I was already pulling pretty short (1:1.2).

If you don't mind wasting a shot...
Add a 10 second pre-infusion to the routine, then follow the recipe but stop it 4-5 seconds short (or taper it off 5 seconds short) and see how that has affected the taste.

Also bear in mind that the term "preinfusion" is not standardized.

If you run a La Marzocco GB5 or Linea PB in your shop, preinfusion consists of running the pump for a few seconds and then venting the brew solenoid for a few seconds before starting the shot. This is far from ideal and if I were giving shops with these machines guidance on dialing in, I would instruct them to turn PI off on their machines.

If a shop were running a Strada EP or a Linea MP, or a Synesso Hydra, I might instead instruct them to preinfuse at 3 bar for some amount of time before starting the shot. But the challenge is that shops have all sorts of different machines setup with different capabilities. A shop with a Slayer Espresso machine will have a different approach to pulling shots than a shop with a Slayer Steam, which lacks the needle valve and associated Pre-Brew capabilities.

Far easier for the roaster to give a simple recipe that is repeatable across machine capabilities by specifying "no PI", even if this recommendation may very well be far from ideal.

Cheers!

- Jake

Jake_G wrote:Also bear in mind that the term "preinfusion" is not standardized.

I'll go further: "preinfusion" is not only nonstandard, but nonsense terminology.

Presumably preinfusion is the initial espresso brewing stage: grinds saturate with hot water, but full brew pressure has not been reached. Per this definition, there is always preinfusion, because this process does not happen instantaneously.

IMHO: Extended preinfusion is primarily useful for "softening" light roasts, which are harder to extract, and benefit from finer grind settings. Extended preinfusion and blooming profiles seem to produce more brew-like espresso, with thinner body and mouthfeel. My clear preference is rapid infusion of the puck, especially for classic medium roasts. Some tout reduced channeling as a benefit of preinfusion, but I consider that a fault in puck prep, easily correctable with correct grind/dose/distribution.

Obviously YMMV. Try different settings and pick the one you enjoy most.

I think the answer is a lot more trivial. The roaster dialed with no pre-infusion because that's the setting that's available to the greatest number of their customers, it's a good baseline, that is all.

If you want to dial with a pre-infusion phase, or with flow control, or with a dipper style infusion and a pressure decrease (aka you have a lever), you can and it could potentially give you better tasting coffee.

They didn't say pre-infusion forbidden, they gave a starting point for "regular" 9 bar pump machines.