Pre-infusion using flow control vs. pre-wetting - Page 3

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Jeff
Team HB

#21: Post by Jeff »

Lever-style shots may be getting more attention as the DE1 user base expands more into the mainstream. It may also be getting more popular as there are user-contributed, lever-style profiles that are more than just marketing fodder. One that seems to be popular is a very clever way of mimicking the behavior of a spring lever with the Argos being used as its model. These are an order of magnitude more complex than the ones the DE1 ships with.

For some of the advanced shots being used by the light-roast contingent, https://pocketsciencecoffee.com/2022/05 ... actamundo/ covers some of the history.

There has been work done on the benefit of relatively short holds prior to the "high" pressure extraction phase. These holds, in practice, have their duration set by the decay of the initial pressure peak.

NB: Most of the people doing this work are using high-quality, light-roast coffees and 64 MP or 98 HU burrs.

PIXIllate
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#22: Post by PIXIllate »

Thanks Jeff, interesting read.

One thing that isn't mentioned is ratios. Are the profiles being used at 2:1 or longer? My taste preferences continue to go in the other direction.

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Jake_G
Team HB

#23: Post by Jake_G »

I know JoeD rarely went past 1:2 ratios with the 98HU for the same reason I don't. They extract so much so early that any more yield is basically just di a uting the shot and pulling out stuff that is best left in the bean.
LMWDP #704

PIXIllate
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#24: Post by PIXIllate » replying to Jake_G »

What EY% range are you finding that happens? Over 22%? Over 24%?

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Jake_G
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#25: Post by Jake_G »

I'm sure it varies by coffee, but I couldn't tell you as I packed my refractometer up quite a while ago.
LMWDP #704

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Jake_G
Team HB

#26: Post by Jake_G »

vit wrote:But ... what would actually force the air above the puck to escape downwards ? Water droplets exit the screen and hit the puck; if let's say flow is that low that all water is absorbed by the puck, air above will stay where it is.
The key is that water is in the headspace at all. As soon as this volume is occupied by water, it cannot be occupied by air, as well.

I don't know the exact details for calculating how much air is expelled, but it comes down to what percentage of the headspace is filled by falling drops/spray of water from the shower screen. Obviously, a fair amount of air is trapped and compressed in typical machines with a 3-way valve, as the expansion of this trapped air is what evacuates the brewing chamber when the valve opens. I'm fairly certain that the flow rate and the headspace volume are the primary variables that influence how much air is displaced vs compressed during the fill.

- Jake
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Ursego (original poster)

#27: Post by Ursego (original poster) »

OK, I see why "pre-wetting" without pressure is worse than "pre-infusion" with the pump running. With "pre-wetting" I can't grind as finely as I do for "pre-infusion".

I've been playing around with it a bit. I ground so finely that after "pre-infusion" the trickle barely flowed and the surface of the coffee in the cup resembled the colors of a leopard. For my next shot I used the same grind size, turned on wetting and waited for the first drops. After 50 seconds of waiting, I realized that the idea failed :lol:, set the valve to 1/8 of a turn and turned on the pump.