TimEggers wrote:Ok sorry for long title, but you get the idea...
I have been long trying to understand the importance and the possible improvement I could realize with different brewing pressures. My humble Gaggia Coffee does NOT have and adjustable OPV and modding my machine seemed a little risky to me.
So an idea struck me (just like when the 2-liter bottle thing went off in my head) what if I open the steam valve during brewing? I thought no it couldn't work; the resistance of the coffee would just force all the water out the steam valve. So I tried it...
It seems to work great! I pulled a shot of some super fresh (4-hour old) Sumatra because that's the only beans that I have. I was surprised to see the level of apparent adjustability I really had. I feared it might be an all or nothing adjustment. Actually I saw a reasonable slow and variable flow rate. I could run with the valve shut to put full pressure to the puck, or open the valve to ramp clear down to no flow at all. I was surprised at the range of the adjustment too, nearly a full half turn of the dial!
The ideal application of this would be I suppose to put a pressure gage on this thing to see where I need to have the steam valve set to in order to get the desired pressure at the puck. This it would seem should work.
Another application of this would be an initial low-pressure delivery of the water to the puck to pre-infuse, then a ramp up to the desired brew pressure.
I believe that if one has a pressure gage they could easily mark where the knob has to be for different pressures.
So there you have it a variable, adjustable brew pressure system that in no way modifies the machine. Best of all the steaming capability isn't affected. Shut the valve, turn the machine to steam mode, wait for steam temp then steam. Nothing to remove or bypass to steam.
There has to be a catch to this whole thing because it is simply just too easy. What am I missing?
The shots I made were noticeable different. Less bitter, smoother body and nice improved sweetness. I have more experimentation to do, but so far this seems like it could be a very viable method.
I made a video to demonstrate this in practice. It's a terrible shot, but I wanted to illustrate and document the affects of the process. If you watch close (and listen) you can see and hear when I open the steam valve. The flow will accelerate and recede as I turn the dial (I was turning it kind of fast).
[gvideo]http://video.google.com/videoplay?docid=-964513537331134489&hl=en[/gvideo]
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Hi there:
I like your video. The concept is really elegant in its simplicity. You can probably do a lot to tailor shots to your taste without needing a pressure gauge. Just watch and taste. Nice going!
-Greg
