Moka Pot - A Crema MONSTER. Wait What?? - Page 4

Coffee preparation techniques besides espresso like pourover.
Jeff
Team HB

#31: Post by Jeff »

You can set a DE1 for low pressures, or observe low pressures when using a flow-driven profile.

Edit: You could accomplish a similar, low-pressure profile by "riding" the flow-modulation valve on an equipped E61 or other machine.

vit

#32: Post by vit »

One of the specifics of moka pot coffee is that extraction starts at 40-50°C and ends somewhere in the range 95-120°C - depending on particular moka pot (different sizes and manufacturers), how much water in the vessel, how much coffee etc, assuming a "cold start" (with water at room temperature). This probably can't be simulated with any espresso machine, but I don't believe that it contributes to better taste either (on the contrary)

If there is even a slight leak (like it is in many cases) it actually starts around 100°C and ends quite high

As about moka pot pressure rating, I didn't find it to be a problem. I regularly used 7-8 bar and went even over 11 bar once, using the strut pump with cheap 1cup moka pot clone ... but it's on own risk ...

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jpender

#33: Post by jpender »

vit wrote:One of the specifics of moka pot coffee is that extraction starts at 40-50°C and ends somewhere in the range 95-120°C - depending on particular moka pot (different sizes and manufacturers), how much water in the vessel, how much coffee etc, assuming a "cold start" (with water at room temperature). This probably can't be simulated with any espresso machine, but I don't believe that it contributes to better taste either (on the contrary)
Are you sure the Decent machines can't go down to 50°C?

According to Illy, the best part of the moka brew is early on when the temperature is low: "The coffee with the most refined aromas brews at around 60 degrees...".

vit wrote:If there is even a slight leak (like it is in many cases) it actually starts around 100°C and ends quite high
I had this happen recently. This thread inspired me to get out my old Moka Express 3 and I've been (mostly) really enjoying the coffee. I sort of forgot how good moka coffee can be. But one morning I had a really hot shot, just like you're describing. I didn't witness any leak but it had to have happened for the temperature to hit 100°C before any coffee emerged (I embedded two sensors).

Sealing is a problem with moka pots in general. All three of mine have nice silicone seals installed but still sometimes there is a little leak. It is probably one reason moka pots get a bad rap. I think there could be a better design than the screw-on sealing. But it's a simple device. Making it more complicated would kind of defeat the point.

vit

#34: Post by vit »

Well, DE1 might be able to come somewhat close to that temperature profile, although it wasn't constructed for that kind of temperature profiling where the temperature is changing that much during the extraction. I didn't follow discussions about that machine for about a year or more, but from my remembering owners were not especially enthusiastic about trying various temperature profiles that are "unusual" for espresso. Main point was always pressure and flow profiling

Interestingly, some italian manufacturers of commercial espresso machines claim that somewhat rising temperature profile is giving better results, contrary to what I think is general opinion on this forum

As about leaking moka pots, I had a 3cup moka pot clone which I used for measurements when we were discussing the "italian moka pot method" and it had very slight leak on the security valve, but it was enough to prevent it from working properly. Had to fix it first. I'm quite sure that lots of moka pot users don't know how important it is and regularly prepare boiled coffee with it ...

I also had Bialetti 2cup moka express that I also equipped with tyre valve to make a kind of espresso machine (like the 1cup one), but it was leaking on the seal if I pumped it to more than about 4 bar ... but ok, it wasn't made for that anyway. Maybe it would have exploded at 9 bar, who knows

At the end, settled down with Flair ...

Jeff
Team HB

#35: Post by Jeff »

As there is flow during extraction, the DE1 should be capable. That the temperature is increasing during extraction should make it even easier. Many unique and novel preparation techniques for coffee, tea, and even dashi are being actively explored. The DE1 seems to attract those interested in medium and lighter roasts, so techniques that would seem to be most appropriate for darker roasts are in the minority.

jpender

#36: Post by jpender »

vit wrote:Well, DE1 might be able to come somewhat close to that temperature profile, although it wasn't constructed for that kind of temperature profiling where the temperature is changing that much during the extraction. I didn't follow discussions about that machine for about a year or more, but from my remembering owners were not especially enthusiastic about trying various temperature profiles that are "unusual" for espresso. Main point was always pressure and flow profiling

Of course it's way outside the box for espresso. The very idea of trying to emulate moka coffee on a $3000 machine is funny. I saw a video of a Decent engineer testing the temperature control. He had it oscillating up and down aout 10°C and the response time was five seconds. I think that's fast enough to simulate a moka pot profile. So maybe it's possible.

If I had a Decent I would try it just for fun. One thing you'd never emulate is the "Strombolian" phase, the sputtering high temperature steam at the end that likely affects (taints) a lot of moka coffee.

Come to think of it, moka brew water typically exceeds 100°C, sometimes by a lot. Gabór measured a Brikka at 120°C. Can a Decent do that? Would you ever really want it to??

vit

#37: Post by vit »

Well, Brikka valve opens at something like 1 bar or so, which is around 120°C ... however extraction is very fast, that's probably why the result isn't that bad. I never owned one, although I simulated it by plugging the spout until 110-120°C and the taste was more-or-less similar to usual moka pot process, just with some additional foam

Moka (usual process, not the one with the pump) was quite interesting to me from engineering point of view (forced me to study long forgotten things) but never really liked the resulting coffee ,,,

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jpender

#38: Post by jpender »

vit wrote:Well, Brikka valve opens at something like 1 bar or so, which is around 120°C ... however extraction is very fast, that's probably why the result isn't that bad.

You're leaving out the partial pressure due to the air. The head space grows by a factor of about 1.4 from start (assuming standard water fill height) to when the water rises to the valve. The valve is initially open to air flow and only seals when the liquid first reaches it.

In Gabór's video it appears that the valve opens back up when the water is at about 112°C. It doesn't reach 120°C (actually 124°C) until the very end. You can try to figure out what the pressure is but it's hard to say exactly. If the vapor were in equilibrium with the water then the water vapor pressure would be about 1.5 bar and the air pressure would be about 1 bar, so total 2.5 bar absolute. That would suggest the valve doesn't let loose until 1.5 bar gauge. But if the vapor is cooler than 112°C the pressure would be correspondingly lower.

I tried to measure the valve release pressure and found that it was inconsistent and easily perturbed. I got a range of values but nothing as high as 1.5 bar. Maybe Gabór's Brikka valve was stickier than mine? Or maybe the pressure was lower?


Why does Brikka coffee taste good when the water gets so hot? I wonder the same thing about moka. Sometimes it also finishes quite hot and still tastes delicious. One thing about the Brikka is that most of the brewing time the coffee is at a very low temperature. The valve turns the Brikka into a low temperature immersion brewer for the vast majority of the brew time. It's a weird profile: steeping at 40°C for 70 seconds and then a very quick rise to 120°C as the coffee is pushed out in 5 seconds. Or at least that's how it was for Gabór. My Brikka brews aren't always so explosive. But the character -- slow steep followed by rapid percolation -- is the same.

vit

#39: Post by vit »

Yes, you are correct about that - I forgot that a few drops of coffee appear before the valve actually opens on Gabor's video, just that I wasn't sure was it imperfection of particular device or intentional behavior. So the coffee actually starts steeping well below boiling point, but considerable less water is percolated in that phase (compared to moka pot), so I suppose that most of the extraction still happens after the valve opens. Anyway, that amount of relatively cold water in the puck slows down the overheating of the puck (like in "new italian moka pot method", where some cold water is put into the basket before the brew)

jpender

#40: Post by jpender »

vit wrote:So the coffee actually starts steeping well below boiling point, but considerable less water is percolated in that phase (compared to moka pot), so I suppose that most of the extraction still happens after the valve opens.
My estimate is that roughly 70-75% of the brew water has already come into contact with the coffee grounds prior to the valve opening. So even though it's relatively cool I would expect that the majority of extracted solids go into solution at that stage.

vit wrote:Anyway, that amount of relatively cold water in the puck slows down the overheating of the puck (like in "new italian moka pot method", where some cold water is put into the basket before the brew)
If I remember correctly, that method of LVX's resulted in a lower final temperature. Isn't that right? But the Brikka puck rises to 120°C. Again this is based soley on Gabór's measurement.

Here's a screenshot from his video: