...and how grinding works, in an Alton-Brown-on-steroids style. Unless you're *not* a coffee nerd (and you wouldn't be reading this if you're not), you should all find this very interesting.

Matthew Perger wrote:The act of grinding coffee is full of mystery and myth. A group of likeminded people recently embarked on a project to shed some light on coffee grinding, and found some interesting results. So interesting, that we decided to turn it all into a paper; subjecting our methods to peer review and the rigorous process of publication. Last week, this paper was published in a Nature sub-journal -Scientific Reports- as open access. This means anyone can read and benefit from the results. Yay for science!

http://www.baristahustle.com/grinder-paper-explained/

Thanks for posting, I just read Pergers comments will have to check out the article later. Bad news for the rafino project. Can easily be used to advertise for the ek43 and the eg1

Sounds like sifting boulders would still not be useless though some of the supposedly tasty fines via static.

On a side topic: Really brings into question his prior comments on sifting though, he was all about how it turned things into real plum flavor etc...if there is no explanation for that game changing experience, not even a comment that it was incredibly effective as he said but doesn't know why, instead just a simple "I will do an apology routine later" well, then he has lost credibility with me at least. I am a teacher so of course am all for gaining information and growing, but if his prior sifting experience is real then his comments at times do not show "growth" as I see it.

day wrote:Really brings into question his prior comments on sifting though, he was all about how it turned things into real plum flavor etc...if there is no explanation for that game changing experience, just a simple "I will do an apology route later" well, then he has lost credibility with me at least.

Or it goes to show that new levels of knowledge and awareness supersede -- are built atop -- and sometimes contradict the earlier ones. The story of civilization.

I don't think you understood my point and I am trying to phrase it in a way that won't be insulting or rude. Ultimately, if sifting made such a difference, as he said it did, why would he now throw it out so cavalierly.

Using an analogy--if I was in the racing business and on a team selling a car that was known For an extremely efficient engine, and then told people that putting ethanol in cars, by itself, radically improved my gas mileage-not marginally but tripled or even quadrupled performance (read hear Pergers comments about grind uniformity, especially when sifting, taking coffees from hints of plum to tasting like biting into a ripe juicy plum). Heck I even win a race and attribute the win to improved combustion and efficiency due to the better fuel source. but then after a couple years I was part of a research project that found that ethanol actually decreases performance and that ethanol will decrease mileage and slow the car down. If I then come out and say "sorry guys, now I am going to win using a gasoline car to apologize" well that, my friend, is not growth and building upon knowledge.

I have always had a tremendous respect for perger, and do not want to insult him, I am just saying that this research and his initial comments on it appear to make clear that his previous statements on sifting was never possible, let alone accurate.

Perhaps further analysis will explain why sifting did make such a difference in the cup for him, but at the end of the day it either did or did not make the profound difference he said it did.

Wounder how they cooled beans to -329F? Or even -110F ??

There is no question that sifting would have impact, but the question is whether it can be done reliably. Coffee grinds have a tendency to agglomerate and form clumps.
With the sifting process it's much easier to remove larger boulders but removing fines is much more difficult.

Anyway it's not so much about sifting I look forward to reading where it leads and am glad it happened, but will take Pergers tips with a larger grain of salt now.

Bill33525 wrote:Wounder how they cooled beans to -329F? Or even -110F ??

They used liquid nitrogen and dry ice (solid CO2).

Bill33525 wrote:Wounder how they cooled beans to -329F? Or even -110F ??

Liquid nitrogen and dry ice and alcohol mixed. It is actually quite simple.



As to sifting being now basically rejected do note the explanation. The vast majority of the fines are tightly attached to the larger particles by the dissimilar charges. What that means is they do not sift out. What is actually sifted out is a very small, insignificant percentage, of the total. The fact remains that the sifting did change the flavor in the cup and this has been demonstrated multiple times.

Before getting too carried away, do note that the conclusions of the paper are based on the shape of the particle size distribution curve by number, not by volume or surface area as is more usual. The main lobe of this distribution consists of particles below 30-40 microns in size, consisting of less than 10% of the grind by volume but more than 90% of the particles by number (from the raw data posted elsewhere). As has been pointed out several times online, these particles can contribute only a small amount to the result in the cup. The practical limit on extraction yield, even at 175C and 10bar, is 50% by mass. If it were possible to do better than this by grinding finer then the instant coffee manufacturers would, most certainly, already be doing so! So of a 20g dose, ground as in the article, there would be no more than 2g of particles below 30-40microns in size, and these could contribute no more than 1g to the dissolved solids in the cup. There would be at least 4g in total in a well extracted coffee, in which case at least 3g of that would come from larger particles.