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Pre-infusion, does it work and how?
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Discussions > Espresso > General > Pre-infusion,...  
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pstam
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pstam
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Posted Sun Sep 17, 2006, 1:16am
Subject: Pre-infusion, does it work and how?
 

When I talked to our trainees this afternoon, a new understanding came to my mind.  It is about "pre-infusion".

Do you believe it?  Or how do you understand it?  Even if you do not believe it but heard about some kind of explanation of it, please let me know and I would compare it with mine.

I do not tell it before we collect all different udnerstandings, in order not to disturb your description and uderstanding.


I am looking forward to hearing as much as possible.

 
Peter in Beijing
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DarkMajestic
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Joined: 9 May 2006
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Espresso: Quckmill Vetrano
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Posted Sun Sep 17, 2006, 11:45am
Subject: Re: Pre-infusion, does it work and how?
 

Hello ..

I'm no expert but here are the two reasons I have read about.

First, coffee expands as it gets wet so pre infusion helps the puck surface seal up as it expands providing a tighter fit when the high pressure water starts to flow.

Second, the pre infusion helps loosen up coffee oils in the puck. Like a pre soak stage before the water really starts moving.

Good Day ...
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emradguy
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emradguy
Joined: 31 Mar 2011
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Espresso: Duetto II; Twist v2
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Roaster: H-B "List of Favorites"
Posted Fri Mar 2, 2012, 3:47pm
Subject: Re: Pre-infusion, does it work and how?
 

I found this ancient thread about preinfusion, because I don't understand it  - when to do it, why to do it, etc.  When I took my barista training course with Heather Perry, she told me don't worry about it, and that was about all the explanation I ever got.  I was using my Silvia at the time (at home, not in her course).  Is the second post accurate?  Can anyone elaborate, or should I just get a book and read?

Would anyone use a manual pre-infusion technique with a Duetto?  Is it worth experimenting?

 
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frcn
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frcn
Joined: 23 Dec 2001
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Espresso: Vibiemme Domobar Double
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Drip: Behmor Brazen, Bunn A10 mod...
Roaster: computer controlled Hottop,...
Posted Fri Mar 2, 2012, 4:29pm
Subject: Re: Pre-infusion, does it work and how?
 

A machine with an E-61 group preinfuses every shot if the group is working correctly. For detailed information on how that works, download the Vibiemme Domobar double from http://www.espressocare.com  The working of the group are diagrammed and described in detail. On plumbed manual E-61 groups, the preinfusion can be extended as long as you want by simply holding the lever up without turning the pump on. This opens the brew valve and allows line water pressure to infuse. Other machines may have to go about it differently, usually though the electronics.

Preinfusion gives the coffee throughout the puck to become saturated and helps give an even extraction across the entire puck. It also swells the coffee which lessens channeling and fracturing. As far as a low pressure water stream assisting directly in any extraction process, I would have to assume that whatever can be so easily extracted at around 1.5 to 2bar could be even more easily extracted at 9 BAR after the pressure increases when the pump kicks in.

 
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emradguy
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emradguy
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Posted Fri Mar 2, 2012, 5:31pm
Subject: Re: Pre-infusion, does it work and how?
 

thanks, Randy!

That's a nice document. I wish the Duetto came with as much detailed explanation.  I'm looking forward to reading it thoroughly.  I skimmed it thus far and noticed in the E-61 section you explained the fully opened valve and fully closed "idle" position.  Again, I plan to read through it thoroughly, but in case the answer is not there...what is the purpose of the intermediate lever position (I'm assuming that what I'm referring to on my Duetto is common to other E-61 group levers - where the lever can be raised about halfway towards open and seems to cick into an intermediate position, without apparently allowing extraction from the puck out of the portafilter)?

 
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frcn
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frcn
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Posted Fri Mar 2, 2012, 6:16pm
Subject: Re: Pre-infusion, does it work and how?
 

emradguy Said:

thanks, Randy!  That's a nice document. I wish the Duetto came with as much detailed explanation.

Posted March 2, 2012 link

They should hire me!

...what is the purpose of the intermediate lever position (I'm assuming that what I'm referring to on my Duetto is common to other E-61 group levers - where the lever can be raised about halfway towards open and seems to cick into an intermediate position, without apparently allowing extraction from the puck out of the portafilter)?

There really is no intermediate position. It feels that way for a couple of reasons:
- it is when the lever's external cam hits the brew switch
- there is a transition internally when the internal cam closes the infusion valve (and indirectly, the exhaust valve) and the lever effort momentarily is very light. Right after that, as the lever moves a bit further, the cam opens the brew valve. If the machine is plumbed, this will allow the water to flow into the coffee at the pressure supplied to the machine. The feedback on the lever causes you to think that this is doing something, or at least to say, that something more tactile, auditory, or functional should be apparent. That's the preinfusion point. Lifting it fully closes the contacts on the brew (pump) switch and holds the lever in the brew position.

 
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emradguy
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emradguy
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Espresso: Duetto II; Twist v2
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Posted Mon Mar 5, 2012, 7:18pm
Subject: Re: Pre-infusion, does it work and how?
 

yeah, they should hire you!  or at the very least, pay you for the work you did.

 
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pstam
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pstam
Joined: 27 Jan 2004
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Location: Beijing
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Espresso: ECM, SAN MARCO, EURO 2000
Grinder: MAZZER
Vac Pot: YES
Drip: YES
Roaster: YES, HOME STYLE
Posted Mon Mar 5, 2012, 7:47pm
Subject: Re: Pre-infusion, does it work and how?
 

preinfusion can really help to avoid uneven extraction, but only for single cup extraction. For double cups extraction, it is not useful at all. Excluding that preinfusion has nothing to do with coffee extraction.

Sometimes, I use manual preinfusion. It's not necessary, but sometimes helps.

This is a really old thread, and I totally forgot it, until someone dig it out these days.
Thanks.

 
Peter in Beijing
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http://www.kaffa.cn/
-------------------
I am looking for the way and the place to extend our trainning courses.
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jwoodyu
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jwoodyu
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Espresso: Allex Duetto II
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Posted Fri Oct 26, 2012, 2:47pm
Subject: Re: Pre-infusion, does it work and how?
 

So while doing some reading to better understand Pre-infusion I came across this twice resurrected old thread.

pstam Said:

preinfusion can really help to avoid uneven extraction, but only for single cup extraction. For double cups extraction, it is not useful at all.

Posted March 5, 2012 link

Why would it act any differently on a double than on a single?

 
Yes i have a reason for leaving SCG off my list, yes it is my opinion, yes it is subjective as opinions are by definition, no don't start a flame war because you disagree.
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frcn
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frcn
Joined: 23 Dec 2001
Posts: 3,351
Location: Northern California
Expertise: Professional

Espresso: Vibiemme Domobar Double
Grinder: Mazzer Kony, Baratza...
Vac Pot: Hario, 2 Cory pots, 1 Cory...
Drip: Behmor Brazen, Bunn A10 mod...
Roaster: computer controlled Hottop,...
Posted Fri Oct 26, 2012, 4:53pm
Subject: Re: Pre-infusion, does it work and how?
 

jwoodyu Said:

Why would it act any differently on a double than on a single?

Posted October 26, 2012 link

It doesn't. it may appear that way to some observers because single are a bit more difficult to dose and distributes because of the shallower coffee bed, so it would appear make one conclude that it works better for singles, but really , it just points out that a poor preparation was being done and the preinfusion helped it.
It does help the coffee expand and that helps to limit gushers, sprites, and other such problems because the coffee expands before the full pressure is applied.

 
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