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Grind Sifting for Brewed Coffee - Page 4

Postby portamento on Thu Dec 31, 2009 3:46 pm

pallen wrote:I've been thinking about this same idea. Does anyone sell a set of screens at various sizes that could be used for experimenting? I dont even know where or how to even search for something like this.


Look for "testing sieves". Soil sampling is one common application.
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Postby j123 on Thu Dec 31, 2009 4:03 pm

portamento wrote:JB,

I think the 630 micron sieve is removing too much from the coffee for 2.5 min pourover to produce a flavorful brew. I would try a full-immersion style brew where you can more easily extend the dwell time, like French Press or Abid Clever. Or find a finer sieve in the 100-200 micron range.

Also, what kind of coffee are you using and how was it roasted?

Ryan


Thanks for the reply. The screen is certainly removing a lot of material. It is an interesting comparison to the distribution graphs at the start of the post and it shows that the cheap grinders have huge partical distributions and no tight peaks. I also have a 24 mesh screen which is about 800 microns. So, I know my particals are somewhere between 630-800 microns. Based on the chart on page 37 http://www.mpechicago.com/coffee/images/uploads/pdfs/SCAA_2009.pdf the brew time is 3-5 min for particles in this range. I will try a longer dwell time (when I get some fresh beans) as you suggest and see how it changes. The beans are from intelligentsia.

My preliminary experiment was interesting to show just how important the GRINDER is in producing a cup of coffee because the distributions of particles are very very different from a cheap grinder to expensive.

Hopefully the longer dwell time/fresher beans brings me closer to the store brewed taste. The only thing that still doesnt make sense is that the refratometer reading (calibrated with distilled water) showed that the cup should have tasted strong/flavorful based on the amont of dissolved solids.
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Postby CRCasey on Thu Dec 31, 2009 6:43 pm

Unless you are using the distilled water for your brewing you may gain a greater understanding of what is being extracted by zeroing your TDS meter with your brew water.

Just a thought.

-Cecil
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Postby fac10 on Tue Jan 05, 2010 3:45 pm

I recently ran across this device while web searching -- it seems relevant to this thread:

http://shopping.netsuite.com/s.nl/c.454...id.7799/.f

Of course, given the price ($165) you'd have to be really committed to sifting coffee to justify one of these.
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Postby another_jim on Tue Jan 05, 2010 4:19 pm

It's an old school grind sizer, at a good price. Apparently, they work for brewing, but not espresso. For cupping or French Press, 70% - 75% should pass through a #20 screen.
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Postby j123 on Fri Jan 08, 2010 6:53 pm

Jim

I know from the posts that you have experience with the guatemala grinder. Do you know the particle size for any specific setting and how the size increases or decreases between levels?

Specifically, I'm curious what a 3 would be in microns and the change of size a half step up or down


Thanks
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Postby dsc on Fri Jan 08, 2010 7:04 pm

Hi,

the numbers on the front plate are not the best way to communicate grind settings as the Guatemala can be easily re-configured by removing the pin from the front knob and changing the burr distance before putting everything back together. It's pretty much the same as every stepped grinder ie. don't trust the numbers.

Regards,
dsc.
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Postby another_jim on Fri Jan 08, 2010 8:36 pm

There's no inexpensive way to accurately size grinds. The inexpensively defined way for standardizing drip and cupping grinds is 70% to 75% passing through a #20 screen (850 micron). This isn't particularly precise; but it's something.

A #40 (425 micron) screen could be used for the same purpose for standardizing espresso grinders. However, the performance of coffee ground for espresso is much less dependent on average particle size, and much more dependent on the overall distribution; so knowing the average size may be kind of pointless.
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Postby j123 on Sat Jan 09, 2010 3:47 pm

Thank you for the replies.

If the #20 micron screen is the top end of the range for drip, what size would be appropriate to limit the bottom end of the grind? I imagine too tight of a distribution isn't good but too wide creates the over/under extraction issues.
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Postby another_jim on Sat Jan 09, 2010 5:21 pm

MPE has a page of articles of which the ones in the Coffee and Tea Journal are informative. The articles have a sales spin; but before you get your wallet out, roller grinders start at 10K or so.
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