Permeation Drip Brewing on a Commercial Scale

This video from Hario was brought to my attention by Barismo’s excellent blog.  Be warned, this is a six minute video of someone making a filter coffee, but have a look at the first half if you care to humour me.

I was sceptical about the uniformity of extraction using this method, but I would rather give it a try than give myself a headache thinking about the fluid dynamics of drip brewing, so I did.  And it’s good.  There was a noticable boost to the base sweetness and a clarification of the top end dark fruit tones of the Colombia Quebradon Co-Op coffee I used for the comparison, even without one of those slightly superfluous kettles and the funky wire cone. 

It looks like a great method for an individual cup, maybe two if you’ve got the ambidexterity skills but it requires your constant attention throughout the process which wouldn’t be practical in a busy commercial setting.  So how do you go about making 8 of these bad-boys at once?  You’re gonna need some way of automatically delivering the water to the ground coffee at the correct rate and with roughly the correct volume.  You need a device which holds about as much water as a filter cone and flows like a filter cone.  You just need to pour through a filter cone right?  I went off to the shed…

…And came back with The Double Decker Automatic Manual Filter Permeator Rack. Bien sur. The idea is that you dump the water into the top cone, go and sort out your other orders and come back a couple of minutes later and collect your beautifully permeated brew.  What actually happened was that despite bunging one of the holes and putting in a paper to slow down the flow, the delivery was too fierce and it flooded the bloom leaving me with a thin cup.  Oh, and I even managed to get the grind wrong.  However, it was not an unmitigated failure, if you can imagine that rack extended for eight cups with a properly made slow flowing cone this thing could do the trick I’m sure.  Thoughts please.

UPDATE

I’ve had to give this another shot. Got the flow rate a little more managable and sorted out the grind. However it seems that the flow needs to increase as the coffee extracts to allow the whole bed to permeate properly and not leave the horrible overextracted doughnut you see in this video. Not only that but the water in the top cone looses too much heat while it’s waiting. Somewhere between these two brews we have a winner.

~ by bombcup on May 31, 2009.