Is pre-infusion obsolete with lower pressure, spraying of the puck and a bplus screen filter? - Page 2

Beginner and pro baristas share tips and tricks for making espresso.

#11: Post by mathof »

Auctor wrote:Which of the Kafatek Flat burrs are unimodal?
I upgraded my Flat from the original Mythos burrs to the Shuriken LM. Kafatek doesn't publish particle size distribution graphs, but there seems little doubt in usage that these burrs are more like EK43s than bimodals.

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#12: Post by Auctor »

You could be right. I wanted to confirm whether your comment was based on an analysis, or if it was speculative. There was some recent discussion on the Kafatek forums about this subject.


#13: Post by longpvo »

I also use the bplus lower contact screen with my Breville, it helps 200% on shower head cleanliness and noticeably better water distribution. With the screen I really needed to pay attention to my temperature offset vs no screen, I was trying to dial in a light floral roast today at 92°C (puck prep, dose yield were all good), and it was just a touch overly sour, tried it again without the screen and voila.


#14: Post by Rustic39 »

I'm clearly out of previous poster's league on this thread, as I'm only a bit over a year into my serious home espresso journey. Also, my only experience has been with my old Elektra lever machine, which is kinda apples to oranges concerning the Op's pointed question. Nevertheless, something I've learned with my set up might be relevant to this discussion....I've almost completely stopped rigidly timing my preinfusions, in leu of waiting/watching the naked portafilter for even drop developments across the bottom before releasing. This technique has all but eliminated sink shots entirely for me. Of course the timing varies with roast/grind/dose, but I don't really have to concern myself much by that point after dialing in from shot to shot when I'm simply aiming for a good drinkable shot. On the other hand though, when dialing in new beans this technique self adjusts to the changes I make in grind/dose/age/humidity etc, to give me a good shot or tell me what I need to adjust to get there. I can use this preinfusion technique to help me dial in by gaining information from how long I have to wait on the preinfusion. Things like tamp pressure, grind and dose all provide good feedback via the preinfusion wait time. For example, I may seek a preinfusion duration of 10 seconds but my first grind gets me only 5 seconds till launch time. I can then maybe grind a tad finer, or tamp a tad firmer, and check the next preinfusion time for results. I've found some roasts tasted best at longer preinfusions or shorter ones, but have always had a decent shot when relying on visual indicators vise blind timing. I suspect this is because using this technique may overcome errors done elsewhere, like tamping wrong pressure or grind off some.

Once when I was distracted, I forgot to tamp the grinds in the portafilter. Upon starting my preinfusion step, instead of a wait for the beads of espresso to start forming typically @10 seconds in, I was immediately presented with a fully involved flow. I simply released the lever at that instant, riding the spring loaded lever to the top, completing the shot. Figured it was surely gonna be a sink shot. Turned out to be surprisingly drinkable!

If I were stuck drinking the same beans all the time, I suppose at some point I'd have to play around with this step more, in order to expand the flavor profile of a given bean, to not get board by the same thing always. Instead though, I'm experimenting primarily with home roasting SO beans, roast levels, etc. Enough going on there to keep me with an endless variety of flavors.


#15: Post by BaristaBob »

Katran wrote:I'm using a Linea Mini, and I modified it for lower flow and lower pressure (pushing about 7.5 bars). I spray my puck with a bit of water to distribute first drops of water a little better. (as seen in the decent espresso video). I also use a bplus filter.

Here's the interesting part: I'm getting better results without pre-infusion (vs infusion of 2 seconds on, 2 off). For the same grind, the TDI's are about the same. The taste is much improved.

What are your experiences with pre-infusion in the lower pressure context?

Well, you certainly can't argue with results. When it tastes good...stick with it. Recently I've been experimenting with the bplus/Flair screen and have observed a few things. First, I rotate through many coffees, but currently I'm drinking three that are med-light to medium in roast level. Therefore I use a fair amount of preinfusion...15 seconds worth. I have a "Slayer" modded Breville 920, so I modulate the flow to get first drops at the 15 sec. mark. After that it's the full 9 bars to the end of the shot. A few people have posted that the bplus/Flair screen slows down the flow significantly, but this has not been my experience. I get the same total shot time and yield with or without the screen (same grind). I'm beginning to think the screen has more impact on flow when there is little to no preinfusion (as in your case).

If I can discern any taste difference it might be that my shots without the screen are a little brighter, but I haven't measured the TDS. Both shots are great, there is just a subtle difference. Anyway, for me I use the screen because I want to tone down the acidity just a bit and accentuate the chocolate note of my coffees. Plus the screen really does keep my dispersion shower screen sparkling clean, and makes my puck knock out of the pf like no tomorrow! If there is a area I haven't explored yet with the screen it would be extraction temperature. I believe bplus says that elevating the group temperature by 2-3 degrees is necessary because the screen acts like a giant heat-sink.

Bob "hello darkness my old friend..I've come to drink you once again"


#16: Post by LindoPhotography »

A few sites selling these similar espresso screens mention it will LOWER temperatures by a degree or two so they recommend increasing your machines temperature to compensate, 92c is 197.6f which is a bit low regardless for a light roast (but could work) so that would explain why it was a bit sour with the screen and fine without it.

Interesting someone else claimed they found the opposite, where the flavours are brighter WITHOUT the screen, and believes the temperatures are actually hotter with the screen? Maybe it works differently for different types of machines? Maybe something like a Decent machine for example if it has a sensor there in the brew head, it might detect the screen is cooler and overcompensate for that? (Just a theory).

I think pre-heating the screen should help prevent it from affecting temperatures much.
On my ECM Synchronika with flow control, I can balance it on the ledge of the machine and mushroom part which gets really hot.
longpvo wrote:I also use the bplus lower contact screen with my Breville, it helps 200% on shower head cleanliness and noticeably better water distribution. With the screen I really needed to pay attention to my temperature offset vs no screen, I was trying to dial in a light floral roast today at 92°C (puck prep, dose yield were all good), and it was just a touch overly sour, tried it again without the screen and voila.


#17: Post by Eiern »

I keep my two screens at room temp as I think that would be more repeatable than not knowing the temp trying to heat it up.

I also have lowered my temp from 94C to 86C with screen for pulling nordic filter roast as espresso with no sourness. I actually found higher temp to have a weird profile where they have a mix of high acidity and lot's of weird 'stuff' that cleared up at lower temp, allowing the sweetness and aromas to get perceived more clearly.

I was very sceptical of lowering temp with light roast, I feared high acidity and a lacking shot, but with the faster flow longer shots I do it works better for me with the lower temp.


#18: Post by LindoPhotography »

You mentioned you've been doing medium or darker roasts lately I think that's the key here, they might not benefit from a pre-infusion as much as a light roast I believe. I've had good results with preinfusions but also have done one where I noticed I was getting some over-extraction as a result (more bitterness).
How/Why do you find the non pre infusion shots are turning out better? Like what is different about them?


#19: Post by Giampiero »

Jeff wrote:Lots of hypotheses, theories, guesses, and even wrong beliefs about what happens during espresso making, like anything that you can't see (and a lot of things that you can).

As a guess, the more quickly you can evenly wet the grinds (including top-to-bottom), it would seem as though the more evenly the puck would extract, all other things equal. With commercial-level roasts (at least, as I assume that was what the experimentation used), the grind coarse, extract fast approach of Hendon, et. al., seems to suggest that a slow infusion isn't needed. The "need" to grind fine with lighter roasts and use soak to soften the puck seems to be a force that opposes that. Who knows?
I agree with you and i think that, without all of hypotheses, theories, guesses, and even wrong beliefs about what happens during espresso making, the coffee business would be already collapsed :lol:

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#20: Post by mrgnomer »

I believe the idea that light roasts are denser and do better with a longer extraction at finer grinds, higher doses and higher temperatures has some merit. Pre infusion would gently increase the extraction time and potential to extract good aroma that might otherwise stay locked in the grind. If you don't have pre infusion control with your machine doing it before puck lock in could lead to better extractions. On medium roasts pre infusion helps a bit but for dark roasts I am currently avoiding the extra extraction time of a long pre infusion. With the new lever I've got I'm experimenting with pre infusion and extraction times using only lever control and find the theory of longer for light roasts and shorter for dark roasts does lead to tastier extractions. All of that is given the grind, dosing, distribution/tamping are dialed in for the extraction time and well done to prevent channeling.
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