# Pre-infusion on a Gaggia



## fatboyslim (Sep 29, 2011)

So I've noticed that high end machines (such as GS/3) have pre-infusion features. This feature is designed to replicate level machines as far as I can tell. The explanation of this feature is:



> Preinfusion helps fuse the puck of coffee together where there might be some weak spots due to inconsistent density, rendering a more even extraction.
> 
> It very well may provide a flavor advantage from the fact that the first batch of water to hit the coffee will have a certain amount of temperature pulled by the coffee itself, making it unable to dissolve certain soluble solids at the beginning. Once the puck has acclimated, it is ready to give up the goods. That's when it needs full pressure.


So my question is two fold. Firstly is it necessary? There are many debates out there so just interested in the views of people here. Secondly has anyone got a technique for pre-infusing on a standard semi-auto machine with a simple On/Off switch? Could you comment on pre-infusion times and on improvements you have noticed?

Thanks


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## truecksuk (Sep 22, 2011)

definately a question that has been on my mind lately


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## MikeHag (Mar 13, 2011)

The auber PID for the Classic has the option of a pre-infusion.

Is it necessary? No. Does it help? Probably, but arguably if your technique is good then you shouldn't need it. It helps in cafes where staff are not necessarily very skilled.

I'm not sure that trying to manually pre-infuse would work. A proper pre-infusion, if I understand correctly, is not at full pressure... it just allows the puck to be pre-wetted to allow expansion of the grinds and help ensure that once the full pressure water hits then more of the grinds are 'washed' and more solids diffused from them... this is how it reduces blonding. Trying to do it manually, the water would still come out at high pressure.


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## fatboyslim (Sep 29, 2011)

MikeHag said:


> The auber PID for the Classic has the option of a pre-infusion.
> 
> Is it necessary? No. Does it help? Probably, but arguably if your technique is good then you shouldn't need it. It helps in cafes where staff are not necessarily very skilled.
> 
> I'm not sure that trying to manually pre-infuse would work. A proper pre-infusion, if I understand correctly, is not at full pressure... it just allows the puck to be pre-wetted to allow expansion of the grinds and help ensure that once the full pressure water hits then more of the grinds are 'washed' and more solids diffused from them... this is how it reduces blonding. *Trying to do it manually, the water would still come out at high pressure.*


I learnt this just now. Tried a few experiments and pre-infusing manually DOES NOT WORK.

The reasoning behind pre-infusing does seem solid and it may help bring out the best in some beans for those that don't have adjustable brew temp machines.

I did notice the Auber PID + pre-infusion at around $210!!!

Does anyone know how that kit runs water through the group at line pressure?

Reduced power to the pump maybe?

Why would top end prosumer machines mostly be kitted up with pre-infusion if it didn't make a positive difference?

Surely designers of prosumer machines expect the person operating it to be able to dose/distribute/tamp properly?


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## MikeHag (Mar 13, 2011)

> Why would top end prosumer machines mostly be kitted up with pre-infusion if it didn't make a positive difference?
> 
> Surely designers of prosumer machines expect the person operating it to be able to dose/distribute/tamp properly?


Well you could say the same about commercial machines too, but in reality the expectations are set at the lowest common denominator, which is probably new, untrained staff, and so it's good that technology helps overcome any human frailties. It does seems that pre-infusion helps with achieving a better extraction so I think it should be welcomed if it means more customers better espresso. I'd have it on my machine if I could, but only on a manual brew button because I'd never use an automatic brew button on an espresso machine.


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## maarten_booij (Jan 28, 2011)

fatboyslim said:


> I learnt this just now. Tried a few experiments and pre-infusing manually DOES NOT WORK.
> 
> The reasoning behind pre-infusing does seem solid and it may help bring out the best in some beans for those that don't have adjustable brew temp machines.
> 
> ...


I've been looking at this kit as well, but as far as i know it does it full pressure. So you could do it manually by turning the pump on for a couple of secs, turning it off for a couple of secs, and then do your shot. This doesn't work. The better manual way I have tested and seems to give ok results is to open up your steam wand a bit. Just so some of the pressure can escape through the steam wand but there will still be some water coming through your group. After a couple of seconds you will see a tiny bit flow coming through your puck (at least if you have a naked PF), when you then close your steam wand it will be at full pressure and the shot will come through.

I'm not a professional or anything, but it is worth 'a shot'


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## SlowRoast (Sep 24, 2010)

I use the preinfusion on my PV, about 8 seconds normally, shots are always better. But I assume this is included on the machine because of the brew temperatures needing the adjust etc?

I tried the manual thing on work's machine, all that happened was when the three way valve took water off the puck, it ruptured right down the middle and I got horrible channelling when I finally extracted...


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## fatboyslim (Sep 29, 2011)

maarten_booij said:


> I've been looking at this kit as well, but as far as i know it does it full pressure. So you could do it manually by turning the pump on for a couple of secs, turning it off for a couple of secs, and then do your shot. This doesn't work. The better manual way I have tested and seems to give ok results is to open up your steam wand a bit. Just so some of the pressure can escape through the steam wand but there will still be some water coming through your group. After a couple of seconds you will see a tiny bit flow coming through your puck (at least if you have a naked PF), when you then close your steam wand it will be at full pressure and the shot will come through.
> 
> I'm not a professional or anything, but it is worth 'a shot'


I tried this a bit today, pressure of water from brew head definitely decreased when water was coming out the steam wand but I tested without PF attached.

What is the exact order of this?

Flush 2oz through brew head, attach PF, open steam valve, press brew switch, close steam valve?


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## maarten_booij (Jan 28, 2011)

fatboyslim said:


> I tried this a bit today, pressure of water from brew head definitely decreased when water was coming out the steam wand but I tested without PF attached.
> 
> What is the exact order of this?
> 
> Flush 2oz through brew head, attach PF, open steam valve, press brew switch, close steam valve?


What I usually do is:

- Flush enough through brew head so the light goes out (boiler will start heating, usually about 3oz)

- Wait until light goes on again

- attach PF

- Open steam valve

- press brew switch

- as soon as you see the first sign of coffee coming trough your naked PF, close steam valve (time depends on how far you open your steam valve. I try not to have it totally open, so the first sign of coffee coming trough takes about 6-7 seconds).


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## fatboyslim (Sep 29, 2011)

Thanks so much maarten.

Tried it just now, and still have half the shot left.

Absolutely fantastic pour from naked PF. Probably best one yet.

Very even and no premature blonding at all.

Best part is....tastes fantastic.


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## maarten_booij (Jan 28, 2011)

That's great! Enjoy







(your post made me thirsty for a good espresso as well, but it's so late I shouldn't...ah...what the heck...)


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## fatboyslim (Sep 29, 2011)

Maarten just to clarify, how much would you say you open the steam valve?

I presume the more you open it the less the pressure of water coming out the group head?

I have tried fully open steam valve for 4-5 seconds then close to allow extraction.

Mixed results.


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## maarten_booij (Jan 28, 2011)

Yeah, I have been experimenting with it as well. I settled now on just opening the valve, so there is still some pressure coming through the group head. Maybe about 10 degrees? So not much at all. usually I can see the coffee starting to come through the filter basket within 5-6 seconds.


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## jimbow (Oct 13, 2011)

Interesting topic. I remember reading that this is one of the reasons that many non-E61 group heads can accommodate such highly up-dosed baskets - they have extra capacity built in intended to provide head room above the surface of the puck where the pressure can ramp up gradually, simulating pre-infusion. Of course full E61 groups support full control of the pre-infusion through the group "leva" in the same way that some La Marzocco and Synesso machines do with their paddle controlled groups. These controls are analogue (as opposed to a simple, digital on/off switch) and so allow the water flow to be varied during the shot.


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## maxscan (May 12, 2012)

Been trying this the last couple of days on my Classic - using about a quarter turn on the steam nob, closing off after about 5 seconds - has made a huge difference to the taste, even on old beans this morning. Getting much richer, sweeter shots - awesome!

Thanks very much to maarten for posting the technique & fatboyslim for introducing me to it!

Btw - how do you thank a member when posting? Had a look on the FAQs but couldn't find anything...


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## fatboyslim (Sep 29, 2011)

Below the post there is a small green bar with a thank button on it.

Glad to hear you're pre-infusing like a pro!


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## maxscan (May 12, 2012)

That's weird - I could see the thanks button below your last post (& have in fact clicked it!) but I couldn't see it below any other posts on this thread - but when I view other threads I can now see it ?? Is there a minimum number of posts or something? Anyway - glad it's working now & thanks again


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