Grinding For Drip in Advance

[Tim Dominick]

Thanks for the great link. Minor correction: lineoleic acid is 1/2 of the OIL....

Good eye, my mistake. I can't read sideways worth a damn and I was using a computer without a printer.

Can anyone more in the know about Swiss Water process talk about how that works in extracting caffeine? Is it similar?

Swiss water uses what they call a super saturated solution where only the caffeine is removed and the rest of the water solubles from a previous lot are left in the water. The idea is that the solution only can accept caffeine from the green coffee and none of the other solubles. As we all know, there is some flavor loss so it is not just a simple caffeine exchange without consequence.

[aaronblanco]

There is a decaffeination process that uses liquid carbonic (CO2), is there not? In that process, if I recall correctly, CO2 is used to stick to caffeine and pull it out of the bean. I think that is also the same or a similar process using Ethyl Acetate to decaffeinate.

No, it's not the same, except in the broad "solvent pulls caffeine out of coffee" sense.

Can anyone more in the know about Swiss Water process talk about how that works in extracting caffeine? Is it similar?

Yes, the solvent (water) pulls the caffeine out of the coffee.

I think discussing how caffeine is extracted via decaffeination is relevant because of the whole binding thing Mark mentioned.

A molecular solid going into solution will form a bond with the solvent. Degassing is a known transport mechanism for volatile aromatics within the bean. Sivetz extracted and isolated these compounds in his efforts to isolate the "fresh" coffee aroma. Reducing or halting the outgassing of CO2 also reduces or halts the loss of these aromatic compounds. Grinding releases all of it... IIRC, 75% of the CO2 is lost when the coffee is ground. A remaining portion is lost when the ground coffee sits. CO2 can impede extraction during brewing (although this is typically not a problem with espresso, due to the pressures used in brewing), and this can be tested with a TDS meter. My experience has been that coffee which has not degassed has to be ground finer than coffee which has degassed in order to achieve similar extraction levels.

Good Lord, that's some rad stuff. Thanks for the edumacation, Barry.

[Andy Schecter]

illy argues (and I've yet to see anything proved otherwise) that CO2 transports oils and lipids to the cup that otherwise would never leave the bean.

Hi Mark, I'm terrible at finding stuff buried in textbooks. Would you mind citing page numbers for the above? Thanks.

[Mark Prince]

Hi Mark, I'm terrible at finding stuff buried in textbooks. Would you mind citing page numbers for the above? Thanks.

LOL - and you think I'm good at it? It took me five tries over a half year period to read Edition 1 of The Chemistry of Quality. And I'm still not through Edition 2, gave up months ago. The case for CO2 and its role in coffee (not just flavour transport, but, IIRC, also as an insulator and protector of lipids during the roasting process as an eg) is stated pretty much throughout the book.

The next time I crack the binding on it, if you haven't found the specific references by then, I'll take a look. It's probably most plainly stated in the percolation section, but (from memory again), I think it's also stated here and there throughout the chemical analysis of roasted coffee, eg lipids, carbohydrates, phenols, all those "ols", etc, and non soluble items that emulsify in the brewing process, and C02 is what most of those emulsifications wrap themselves around as they go from puck to cup.

Mark

[barry]

The next time I crack the binding on it, if you haven't found the specific references by then, I'll take a look.

I went through it last night and couldn't find anything supporting the "otherwise never leave the bean" contention. That doesn't mean it isn't there, of course, only that I couldn't find it in the hour I browsed.

[Mike White]

Mark and Barry, thanks for the great technical info. I'm still curious though, there's no doubt that a lot happens because of the CO2 (during roasting, grinding, brewing, etc), but I'm still questioning whether the loss of it is inherently bad for the flavor in the cup. I've never challenged the notion of grinding on demand before, and I don't think I've tasted coffee that was ground 12 hours earlier in the years that I've been working with coffee seriously. It's such a fundamental principle in this industry that I wonder how many have actually participated in this type of blind taste test?

[barry]

I've never challenged the notion of grinding on demand before, and I don't think I've tasted coffee that was ground 12 hours earlier in the years that I've been working with coffee seriously. It's such a fundamental principle in this industry that I wonder how many have actually participated in this type of blind taste test?

A part of this is tied in with expectations and methods. If one is expecting a crisp cup, then coffee which has been ground some time before brewing may not be as crisp as desired. If one is measuring extraction levels, then just-ground coffee can come up short. If one is looking for body, then blah blah blah. You get the idea. I can totally see several people coming up with different preferences in blind cuppings, and individuals having different preferences for different coffees (eg. just-ground Costa Rica and pre-ground Sumatra).

Ain't it fun?

[Matthew Brinski]

The CO2 aspect is interesting, although I don't buy into its importance in brewed coffee preparation other than a partial indicator of freshness while creating a visually appealing bloom. I interpreted the reference to CO2 utilization for oil flow as its use for recovery under high pressure. That seems somewhat relative to espresso but not to brewed coffee.

If there is some further scientific reasoning as to how CO2 significantly promotes the extraction of compounds from coffee, I would be really interested in the explanation ... seriously.

Despite all of that, doesn't the following statement trump CO2 when discussing the thread title? :

Grind on demand -- I'm currently not buying any theory that has coffee sitting exposed to O2 in a ground state for any period of time before brewing. O2 is nasty stuff.

If variances of quality are discovered in the taste tests, I would attribute such differences to oxygen's interaction long before giving credit to CO2 presence (or lack thereof).

Matt

Oxidation is a bitch

[barry]

Grind on demand -- I'm currently not buying any theory that has coffee sitting exposed to O2 in a ground state for any period of time before brewing. O2 is nasty stuff.

If variances of quality are discovered in the taste tests, I would attribute such differences to oxygen's interaction long before giving credit to CO2 presence (or lack thereof).

If O2 uptake is related to CO2 outgassing, then there might be a "sweet spot" of minimum uptake & maximum degassing, like the economic supply/demand curve.

--barry "more of andy's thought experiments"

[Mike White]

If O2 uptake is related to CO2 outgassing, then there might be a "sweet spot" of minimum uptake & maximum degassing, like the economic supply/demand curve.

I had the same thought Barry. Of course, that sweet spot might only last an hour, or 5 minutes, and the logistics of always brewing within that window are daunting. It would be great to find it though...

[Tim Dominick]

Finding the sweet spot would be akin to seeking a needle in a constantly moving haystack.

Variables ranging from room temperature, barometric pressure, # of hours from the roaster, humidity and much more come quickly to mind. Followed by the thoughts of dozens of pounds of great coffee tossed aside if the peak is missed.

Oxidation is not good for anything relying on complex aromatics as a pillar of quality. Based on Sivetz's research, time and oxygen are the worst enemies of coffee. Given these things I am inclined to believe grinding 12 hours ahead will lessen aromatics and hasten oxidation.

My favorite grocery store has a bakery/coffee bar run by a local roaster where they grind the night before and stack the filters in a tub for the next morning. The coffee always tastes stale and the coffee is never more than 4 days from the roaster. There might be many issues at play, but the same coffee freshly ground doesn't taste as bad.

[barry]

Oxidation is not good for anything relying on complex aromatics as a pillar of quality. Based on Sivetz's research, time and oxygen are the worst enemies of coffee. Given these things I am inclined to believe grinding 12 hours ahead will lessen aromatics and hasten oxidation.

I agree that 12 hours might be too long. When we need to brew a high throw weight of really fresh coffee, we'll usually let the ground coffee degas for 1/2 hour or so before brewing. That seems to be sufficient to prevent excessive blooming.

Another factor which enters into this is turbulence during the brew cycle. Turbulence helps offset the extraction inhibiting effects of CO2. Automatic drip brewers typically do not have a great degree of turbulence (although they're getting better). Pourover drip, french press, urns, and <gasp> Clover have better turbulence.

[Mark Prince]

The next time I crack the binding on it, if you haven't found the specific references by then, I'll take a look.

I went through it last night and couldn't find anything supporting the "otherwise never leave the bean" contention. That doesn't mean it isn't there, of course, only that I couldn't find it in the hour I browsed.

What the heck is going on!!!???

I just went through the first edition again last eve (well, skimmed it), looking for "C02" and "Carbon Dioxide" everywhere I could, and besides some references in the grinding section (CO2 released, carrying along with it the chemical compounds that make up aroma), and frequent mention of emulsified oils and non solubles, then sideways mentions of CO2 making up a lot of the crema release, I couldn't find a direct mention of the "CO2 is the transport mechanism" in the book. It could be there, I couldn't find it this read through.

But I swear up and down, this is what I took away from the Illy book when I read it several times over back in 2002. And, it was one of the points I briefly talked to Dr. Illy (RIP) and his assistant about in Boston at SCAA. And even before I read the book, others in espresso would parrot this mantra; I remember talking to David Schomer and John Blackwell, as well as others about it back prior to 9/11, and I have memories of one or both of them referencing the Illy book to me as how to find out more about it.

I've been scratching my head about this for the last few hours. I *know* I read it, and remember finding the scientific data on it hard to understand. There is two other illy books - one I own, but it's out on loan now - the Book of Coffee by Francesco and Ricardo Illy; and there's that other book which I borrowed once (I think from Kent Bakke), the one that has the visuals of the transparent portafilter setup. I read both of these around the time I read Chemistry of Quality, and maybe all these years I've been confusing the source.

I'm also wondering if it's mentioned in Schomer's first books. I've also lent out my copy of that one, (same person who has my Illy Book of Coffee book) so I can't peruse.

Has anyone got either of the other Illy books (esp. the transparent portafilter one, which I don't have, and don't know the title of) to check this out? Now it's getting frustrating. I'm going to go through the Chem Quality book again over the weekend to see if I missed it.

Mark

[phaelon56]

I've never challenged the notion of grinding on demand before, and I don't think I've tasted coffee that was ground 12 hours earlier in the years that I've been working with coffee seriously. It's such a fundamental principle in this industry that I wonder how many have actually participated in this type of blind taste test?

It wasn't a blind test but I did something vaguely along those lines when I attended an open house at Terroir Coffee. Perhaps Peter L can fill in the details or correct me when I'm wrong but one of the comparative brewed coffee "tastings" all the guests participated in went as follows:

#1 - fresh ground from green beans that were transferred to mylar when first received and then frozen for ~ one year

#2 - fresh ground from green beans that were transferred to mylar when first received and then stored at normal room temps for ~ one year

#3 - fresh ground from green beans that were left in the original jute bags and then stored at normal room temps for ~ one year

#4 - ground one week before being brewed and stored at room temp - possibly exposed to air but I'm not sure about the latter parameter. Also can't recall what the bean storage method was for that batch but i think it was the same as batch #1

There were distinct differences and if I recall correctly the worst batch of the bunch was the fresh ground from jute bag storage. The baggy quality that I had read about but found it difficult to elucidate was self-evident. The batch that was ground one week before brewing was very flat but didn't have the disagreeable baggy quality. And those of us (i.e. me) who were even slightly skeptical about whether our palates were discerning enough to taste a difference between the frozen and non-frozen green beans got a real wake-up call that day.

As I said... I did this awhile back and may be fuzzy on a few details but it was extremely enlightening.

[Mike Paras]

regarding "otherwise never leave the bean",
Has anyone tried bubbling CO2 through say, a press with coffee and water during the steep time to see what effect it has? Seemslike all you would need is a press pot, a soda syphon and protective clothing.

[Jim Schulman]

... to test this for ourselves, but I was wondering if anyone else already has? I believe Nick mentioned this in a podcast once, as did Scott Rao in his new book. Any thoughts?

Abe Carmeli did a quick test, in which I participated, just to see if it is worth pursuing. It is.