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PostPosted: Tue Nov 25, 2014 12:11 pm
by simonp
CakeBoy wrote:Any chance of photos? :)


Indeed!

PostPosted: Tue Nov 25, 2014 12:33 pm
by simonp
Or to see in full resolution though from a mobile so not great quality :oops:
https://www.dropbox.com/s/x5g941i4ufg8m ... 1.jpg?dl=0

PostPosted: Tue Nov 25, 2014 6:56 pm
by CakeBoy
Looks nice though, you must be really pleased :)

PostPosted: Wed Nov 26, 2014 10:11 am
by simonp
CakeBoy wrote:Looks nice though, you must be really pleased :)


So far, yes. Though I'm having to completely re-learn steaming milk as the technique with a 4-hole tip and lots of power is totally different. A short aggressive stretch followed buts lots of texturing seems to be the way. My old 2-hole (or 1-hole) technique was a long slow stretch and a short texture. There is also little room for error or accidental movement of the pitcher height without wearing the milk for my morning cappa :lol:
If you get it right though the milk texture is something else 8)

PostPosted: Fri Nov 28, 2014 6:10 am
by CakeBoy
Yes that is the way on Anna too, just a very quick introduction of air and move to the centre with a giant vortex. Indeed, any blip and it's ruined. Anna is sub ten seconds for a small pitcher.

PostPosted: Fri Nov 28, 2014 9:23 am
by simonp
CakeBoy wrote:Yes that is the way on Anna too, just a very quick introduction of air and move to the centre with a giant vortex. Indeed, any blip and it's ruined. Anna is sub ten seconds for a small pitcher.


Blimey the Profitec isn't quite that quick, probably 20 seconds (though I haven't timed it). You do seem to get a sweeter, better textured result though.

Speaking of which I managed to nail the cappuccino this morning for the first time. I've had a few (very good but unintentional) flat whites and one VERY frothy cap, but got the foam proportion and texture nailed this morning. A tiny bit more in the pitcher helped. Actually it was one of the best cappas I've ever had. I was using Extract Coffee Roasters Original Espresso blend. Boy is that stuff nice with milk. Caramel, chocolate, nuts and a hint of fruit/cherry.
It pulls a damn nice straight shot too. Old-school in some ways but with the lighter fruity sweetness of more modern blends. It is quite intense and I have ended up dropping to the 17/18g VST basket rather than the 20g one I usually use.

I am going to go back over some beans/blends I have had in the past and see what the new machine makes of them. A few were tricky buggers with the Rituale, I struggled a bit with Square Mile Red Brick blend, it was sometimes great but others too acidic. The same with Hasbean Kicker. I'm hoping the better or more consistent temperature control with the Profi means I can get better results with the more finicky beans/blends, including some of my home roast beans.

PostPosted: Fri Nov 28, 2014 7:33 pm
by CakeBoy
It is always fantastic to nail one. It sounds as though she has quite the sweet spot when it comes to shots. Will be interesting to hear how the revisited blends pan out. It's all rather exciting.

PostPosted: Mon Dec 08, 2014 1:53 pm
by simonp
OK, so now we are getting to grips with the profitec. I had some issues with a tendency towards doughnut extractions (i.e. pours starting from the outside with a dead-spot in the middle) when watching using the naked portafilter. I went through a few steps to improve my dosing, but also using a fake pre-infusion seemed to help. As the machine is not (yet) plumbed you cannot do proper pre-infusion but you can wet the put with the thermosyphon water. For some reason doing this for a few seconds seems to make the pour start mostly evenly, unless of course it just coincided with my technique improving!

I also found I needed to shorten my expected shot time. With a vibe pump machine there is quite a bit of dead-time after the pump coming on to the pressure building up enough to start the pour. With the rotary pump this happens more quickly so the shot naturally starts quicker and is over in a shorter total time for the same actual extraction time. With the old machine I would shot for 30-35s from pulling the lever. With the new one I need to go for 25-30s to get the same effective shot.

I have also played with some temperature differences. One particular blend was bland until I dropped down to 91C whereas another needed to be at 94C to keep acidity under control. Whilst this was possible with the old HX machine it is WAY easier with the dual boiler one, albeit that you cannot change on the fly, you have to wait 15 mins or so for stabilisation. However I mostly change the temperature for the next time I do a shot which may be some hours later or the next day, so not a real hindrance.

I also got round to adding in the grouphead thermometer fitting. What this revealed was that the grouphead idles at around 88-89C so not far below brew temperature. It also showed that with the factory recommended temperature offset in the PID at 14C (i.e. if I select 94C brew temp the PID sets the boiler at 108C) then I get pretty much the set temperature of water hitting the puck, so it looks like Profitec did their homework well.

Of course in the spirit of upgraditis I am now wondering if my old Mazzer Mini with it's 58mm burrs isn't limiting my machine and am scouring ebay for a used 64mm (Super Jolly) burr grinder instead :roll:

PostPosted: Mon Dec 08, 2014 3:54 pm
by HughF
simonp wrote:Of course in the spirit of upgraditis I am now wondering if my old Mazzer Mini with it's 58mm burrs isn't limiting my machine and am scouring ebay for a used 64mm (Super Jolly) burr grinder instead :roll:


You could also look at conical burr grinders - my Macap MXK is MUCH more forgiving of different grind settings than my Mini E (which broke down) was and gives noticeably better shots. Scott at www.HappyDonkey.co.uk kindly special-ordered the MXK for me a few years ago and he still seems to sell Macap grinders.

There was a massive test of high-end grinders from 2007 onwards which is linked here with other useful grinder posts :
http://www.home-barista.com/grinders/faqs-and-favorites-t6082.html#p72994
Just look halfway down the page for the "Favourites" section - it was called "The Titan Grinder Project".
The Super Jolly came out pretty well as I remember it - the upshot seemed to be that a more powerful motor gave better results if other things were equal, even if smaller grinders seemed to have capable but smaller motors.

Cheers,

Hugh

PostPosted: Mon Dec 08, 2014 7:29 pm
by simonp
I'm afraid the missus (and my bank balance!) wouldn't tolerate that sort of price for a grinder after the expense of the dual boiler machine.

However I do seem to have just won an ebay auction for a used one of these:

http://www.fiorenzato.it/en/prodotto/f5-2/

Looks a bargain at £173. Very similar to a Super Jolly, same burrs etc and similar quality by all accounts.
Hopefully I can recover most of that by selling the Mini :)

PostPosted: Tue Dec 09, 2014 11:59 am
by dr.chris
Very quick physics lesson on hydraulic conductivity. (RE pre infusion behaviour). This is based on what I know of similar processes which occur on a larger scale. I am not an expert on coffee extraction, but I am an expert on using leaching to extract metals, such as gold, nickel, uranium and especially copper, from ore.

Dry material is more resistant to water flow than wet, so water will go through a wet puck faster. (And its the simplest reason why if channelling starts its not going to get better). Water will move through the puck by conduction (pressure force from above) and through diffusion/capillary action (Capillary action being a pressure load based on relative saturation).

This is assuming that any swelling of coffee particles is small. It is worth thinking that yes swelling may fill in some of the flow paths around the coffee grounds but they will also open up other paths more. Particle size effects is for another lecture... As is reaction/diffusion kinetics. I could also talk about carbon dioxide release but would have to be careful that I am not talking rubbish.

I will say that diffusion rates are always some variation of something which is initially very fast and then tails off slowly. Depending on what is dissolving (and other factors) you can get a fairly linear response for a while after the initial peak.

If you preinfuse a puck you are putting enough water in to diffuse through the puck to change its flow characteristics. At the same time the water itself will be in contact with the coffee particles and will be extracting the soluble compounds. This extraction will be very quick - the intial peak- as all the easiest compounds to liberate will be available, but will be limited by the volume of water and the solubility of the compounds. It could become saturated which will slow extraction.

When you then start the main extraction the first thing that happens is that the new water pushes out the preinfusion moisture, but beyond that its flowing through an evenly saturated puck (nice even flow properties) with (I am guessing) many of the main soluble compounds on the 'linear' part of the dissolution curve. I.e. its all very controllable and predictable.

Lesson done. Debate welcome, even if/especially if you can show me to be wrong :)

PostPosted: Tue Dec 09, 2014 3:00 pm
by CakeBoy
I need a Nescafé! :)

PostPosted: Tue Dec 09, 2014 3:18 pm
by GreenBean
dr.chris wrote:... but I am an expert on using leaching to extract metals, such as gold...

CakeBoy wrote:I need a Nescafé! :)

I need to know how to leach gold from used coffee pucks :wink:

PostPosted: Tue Dec 09, 2014 3:21 pm
by simonp
I THINK I got most of that
So, in short! You are saying that pre-infusion ought to make the shot extract more evenly?

PostPosted: Tue Dec 09, 2014 3:25 pm
by dr.chris
Yes!

If you dont preinfuse you are dependent on the behaviour of the wetting front - in other words the water may not flow through the puck evenly

GreenBean wrote:
dr.chris wrote:... but I am an expert on using leaching to extract metals, such as gold...

CakeBoy wrote:I need a Nescafé! :)

I need to know how to leach gold from used coffee pucks :wink:


You know they use cyanide to leach gold dont you?