That makes 27 cups. Does brew ratio affect extraction rate? Agitation? What about degree of roast? If you include those as variables you'll need to brew 3^6 cups. And if you insist on at least one replication per case that makes... more than year's worth of coffee!
On the high strike temp brews, this grounds drop at this grind level happens around 2-3 minutes. With the lower temperature, the grounds drop around 6 minutes. I'm wondering if this is a potential signal that the brew is approaching equilibrium.
At this point would it be easier and possibly more accurate to oven dehydrate the grounds?
By the way, how well can you correlate extraction yield from oven dehydration with what your refractometer tells you? To what extent can you simply take what you've filtered out of the beverage and add that to the dried grounds to get the same number? And what kind of filtering do you need to do to achieve this?
I'm curious because when I measure extraction yield of a moka pot brew through dehydration the value is always high even when the coffee tastes sour. I know there are a fair amount of solids in moka coffee; is it enough to simply filter the coffee through an Aeropress or does too much pass through this way?
jpender Senior Member Joined: 11 Jul 2011 Posts: 535 Location: California Expertise: I like coffee
Grinder: OE LIDO Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Mon Jun 4, 2012, 1:14pm Subject: Re: Coffee Extraction Discussion, Questions for the membership:
So, bottom line is dehydration will carry some error with it unless you filter it with a VST filter or centrifuge the sample. The grounds drying will be somewhat close, but will also carry the error as well, with no way to recover it. Unfortunately, this error will be dependent on the filter, the grind size and how much fines are produced with the grind.
That's what I thought. I'm disappointed in that it seems that I cannot expect to reliably adjust for it.
For moka coffee it might make sense to use solids yield like with espresso, instead of extraction. But to calculate the beverage strength you need to know how much of those extracted solids are dissolved versus undissolved.
Which leads to the question, how does mojo/VST do it?
With a refractometer all you know is the TDS from the filtered sample. The only way to determine the amount of undissolved solids, aside from dehydration, is through some function that relates dose and TDS to total solids. If you can do this with espresso why couldn't you do it with moka?
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