Pre-Infusion, longer vs. shorter?

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F.M.

#1: Post by F.M. »

Thats the question!
I've been experimenting with shorter (:08) and longer (:15) but with so many other variables I'm having a hard time finding the difference in shot quality.

Anybody have thoughts to share on this?

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timo888

#2: Post by timo888 »

The goal of the preinfusion is to saturate the coffee thoroughly so that it expands under hydrostatic pressure, presenting uniform resistance against the inlet water, resulting in an even extraction.

Once you get into the :08 range, you're into the long-ish preinfusion, and there's not going to be much of a difference between one longish preinfusion and another. The difference will be most marked between short and long, :02 vs :08, for example. But even that difference can be masked if your boiler pressure is high.

Higher p-stat settings can build up enough boiler pressure to preinfuse fairly thoroughly in a few seconds, if the basket has not been overcompacted. (I'm not recommending high p-stat settings, just pointing it out. I keep my pstat fairly low.) Are you using boiler-pressure-only preinfusion or are you assisting with gentle semi-demi-pulls on the lever?

Your coffee must have room to swell in the basket -- i.e. dose is another important factor when trying to assess the effects of preinfusion. Best to experiment with a moderate dose.

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F.M.

#3: Post by F.M. »

Thanks for the info, that helps!

I've been wanting to make a quick video of one of my pulls to solicit "constructive criticism".
My P-stat levels out at about .85bar, and I usually pull two doubles in a row every AM.
This is on a Pavoni Pro and I use a rocky grinder.
General technique goes like this:

-Fill double basket to the rim, rotating & shaking basket as it fills. Level off with side of finger.
-Tamp directly downward @ 30lbs, polish. No tapping. Shake off excess grounds.
-Pull 1-2oz of water through the group head w/o the portafilter
-Pull lever up to just below where water comes through the group head
-Lock PF, pull lever up to the top
-Wait 8-12 seconds for pre-infusion (sounds like this is too long)
-Pull 1/3 way down (so the bottom of the cup is covered), slowly raise back up to top, pull down completely for double shot.


I generally set my grind so it takes a good bit of force to pull the lever down, but the espresso flows in thin mousetails, not drips.

I think there's room for improvement, since although I get crema, it doesn't always last long.

EspressoForge

#4: Post by EspressoForge »

Try a ~5s preinfusion and a single pull just for kicks to see what you get as a difference. Do you have a 0.1 gram scale for dosing testing?

Low crema by itself isn't an indicator of bad espresso, but it may be an indicator of the age of the beans. How many days post roast is your coffee normally?

Only other change I would try is to pull lever to near fill point, then lock in the portafilter, then raise all the way and pull the shot. This always worked better for me on the pavoni.

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F.M.

#5: Post by F.M. »

I do not have a scale....
Low crema by itself isn't an indicator of bad espresso, but it may be an indicator of the age of the beans.
Definitely not happy with my current pound of beans.
I get one brand for free, but find them to be marginally fresh (no date stamp). Still I use them %50 of the time to save money as I go through a lot of beans, and they are typically acceptable but never inspirational. The other %50 I get from Vivace, 1-2 days after roasting.
Only other change I would try is to pull lever to near fill point, then lock in the portafilter, then raise all the way and pull the shot. This always worked better for me on the pavoni.
This sounds exactly like what I am doing, minus the fellini move (where I've bee doing an additional 1/3 pull)
So you are suggesting I ditch the fellini move? I'm certainly not attached to the results.

Thanks for the ideas!

EspressoForge

#6: Post by EspressoForge »

I would suggest picking up a gram scale and playing with doses, most coffees seem to have an ideal dose for my tastes, and if you aren't getting something you really enjoy chances are you should be changing your dose if everything else is going well. You can also try it without the partial pull and see what happens, it's never worked out well for me on the Pavoni as it always seemed to fracture the puck and cause channeling. But maybe with a coarse grind and heavy tamp it would work...

As to pre-infusion itself, I think in general it's important, but mostly the fill time + a couple seconds extra seems adequate to me. Longer I don't find makes a large difference. Of course in my Caravel filling time takes a bit longer than the steam driven Pavoni...

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timo888

#7: Post by timo888 »

F.M. wrote:I get one brand [of beans] for free, but find them to be marginally fresh (no date stamp). Still I use them %50 of the time to save money as I go through a lot of beans, and they are typically acceptable but never inspirational. The other %50 I get from Vivace, 1-2 days after roasting.
Stale beans are a waste of time if you're trying to hone your skills. It's like carving soap with a mallet and a chisel to practice sculpting marble. You might be getting to wield the tools, but the practice medium doesn't give you a feel for the real thing.

You might try the Chicago Chop to settle the grounds -- chop with the edge of the spoon handle across the rim of the basket in a cross-hatch pattern. Better than shaking the basket.

With freshly roasted beans, you can grind finer and tamp lightly. My practice is to create a fluffy, fine grind, dose about 8-9 grams in the single basket, chop to settle, and press with only 2-3 pounds of tamping force, maximum, just enough to create headroom. 5-second preinfusion, slight Fellini.

With thin crema that dissipates quickly you might be overextracting because the machine is too hot. Try skipping the warming flush and see how that affects things. Use the Vivace 8)

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orphanespresso

#8: Post by orphanespresso »

I do not think that I have ever read such a concise bit of insight on pulls with a La Pavoni EVER!!!!

but allow a few observations on preinfusion.....we were just at CoffeeFest Seattle and Cafe Vita had their Bosco two group on the trade floor and there were two Victoria Arduino two levers as well (though not serving the best masters) and we were paying close attention to preinfusion times and in all 3 cases....Cafe Vita was the most attentive to actual espresso on the Bosco....no more than 5 seconds preinfulion time. they were shooting for extreme Ristretto and they were using their special CoffeeFest blend which was their usual espresso blend with some new Ethiopian they have just gotten in. While in Seattle we went to Hal Parry's and fiddled around with his Termozona HX one group and same thing 3 to 5 seconds preinfusion....tops. Never with a single drop during preinfusion. And then we come home to our Faema Wallbanger.....so our no tamp process (similar to Timo's description ie light or no tamp) and get drops at 5 seconds with a slowdown of drops (indicating that the puck is self packing.....an effecct I appreciate personally)....at the slowdown of drops I release the lever and get not a real long lasting crema but a very flavorful pull (using single origns beans from Stumptown).
The group heat on the La Pavoni is such a huge concept here. We have tested our line pressure at 1 bar and so on our machine we are preinfusing at 1 bar. If you have your machine set at .85 for heat control there is not going to be full preinfusion to the point of drips. Check Juanjo's videos with his Brunetti and he gets drips coalescing under preinfusion pressure which seems to be what one wants in any lever extraction.....full infusion of the coffee in the basket before application of lever pressure.

By the way, the Cafe Vita Bosco was very nice....a little old school with some cheesy braided brassette trim, but a very nice CMA group, very classic rectangular Italian "I am here to work not look good" format...lots of polished chrome panels....but really, the best shots in the room. The 2 group VA machines aslo very good and quite a small footprint (cost $8000) and the same group and lever as well, but lots of fancy hammered copperette and chrome. We went to Cafe Vita later that day and they use a Synesso 3 group and the shots at the store were not even close to flavor and just plain OOOOOOHHHHHH factor as the ones on the Bosco lever.....but the Baristas at the store were much cuter.

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peacecup

#9: Post by peacecup »

Allow me to say that I pre-infuse for a much longer time - 15 sec or more. I preinfuse by applying pressure until the first drop falls into the cup. Then I wait a moment, refill the piston, and preinfuse again. This second preinfusion requires less pressure, and usually a couple of more drops will fall into the cup. Then I refill the piston and pull the shot.

I don't always follow the above technique, but i do it often enough to know that it works. Would it work on the Pavoni, which is more prone to overheating than are my machines? Not sure, but probably depends on the p-stat setting.

The theory behind my preinfusion method is that I'm getting a more even and thorough soaking of the puck by giving it a little more time. I have never found it to result in any bitterness whatsoever, nor do I see any other signs of overextraction in the cup when I have the grind adjusted properly.

Lastly, the whole thing revolves around both the beans and the temperature. There are just so many different kinds of coffee beans, that I only know the way that my favorite blends behave. Currently these are commercial Italian roasts, which I've found to be so much better than I expected them to be. I think they are supposed to be pulled around 90C, and maybe that's why my method works for them.
LMWDP #049
Hand-ground, hand-pulled: "hands down.."

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F.M.

#10: Post by F.M. »

orphanespresso wrote: If you have your machine set at .85 for heat control there is not going to be full preinfusion to the point of drips.
Interesting- do you think it's wort increasing the pressure? I had fiddled with my P-stat and couldn't really figure out which direction would increase pressure.
timo888 wrote: With thin crema that dissipates quickly you might be overextracting because the machine is too hot. Try skipping the warming flush and see how that affects things.
I often wonder if I am just over-extracting due to too fine a grind. No oil globules, but about half my shots require serious work on the lever. I'll try backing off my grind a bit.

I actually found a very quick flush helps- just enough to get any "old water" out of the group head? I don't know... it seems like, when I let the machine warm up for only 10 minutes, no flush, pull three shots, the second one is the best.

Anyways thanks everybody for the ideas!