I've read a lot of discussion regarding the length of time to rest beans.= But I haven't come across anything regarding variables besides time & beans = (type of bean, roast level). For me, other variables include method of storage = (valve bag vs. mason jar with a vacuum seal via Foodsaver), and how often the = bag or jar is opened (& for how long). In particular I wonder the effect of opening & resealing the mason jar. Presumably, the beans release gases faster into a vacuum than into air, = until partial pressures equalize (or something like that, since it's been a = LONG time since I've taken a physics class! :) ). Then if air is let into the jar = for a short time, there is some kind of gas exchange in both directions; if = the jar is quickly resealed, however, this exchange is minimal before a vacuum is re-introduced, at which time the beans proceed to lose more gas. So, in = this scenario total gas loss is much faster than if the beans are stored in = air, or in a vacuum which remains sealed. The result would be a reduced rest = time (assuming the positive effect of rest is simply loss of CO2 or other = gases), but conceivably a reduced time until the beans become stale (depending if = loss of gas contributes to this). Does this make sense? Has anybody considered these issues further? Dave ========================== ========================== ===== Dave Morgenlender e-mail: dmorgen ========================== ========================== =====
Yes, have pondered the imponderable. (Though based on numerous discussions as well as taste comparisons over the years totally unconvinced roasts out gas faster vacuum sealed as post presumed.) Bottom line found it's best to just use brew 'em up in a week or two, differing roast storage methods really have little impact that way! But yes I'll continue to be extreme and vac jar my roasts:-) Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Kurmudgeon miKe mcKoffee URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must first not know. And in knowing know I know not. Each Personal enlightenment found exploring the many divergent foot steps of Those who have gone before. Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/ <Snip>
On 4/18/07, miKe mcKoffee wrote: <Snip> MiKe - "Bottom Line" is: what works for you, works for you. Sic'em, Tiger! Safe Journeys and Sweet Music Justin Marquez (CYPRESS, TX)
I didn't mean that roasts outgas faster in a vacuum. They probably do, = but only to the point of equalizing partial pressure, so it's probably not a = significant factor. But, the amount of gas lost from the bean is presumably greater = into a vacuum. And, each time the jar is opened then resealed, the beans are = exposed to 0 partial pressure (or very close to it, since not a perfect vacuum, = and presumably there is some CO2). So it outgases again after each reseal. = This might result in greater total outgasing using a vacuum than a valve bag. = I don't know if this is in fact true, but it's my theory! Dave On Wed, 18 Apr 2007 12:39:10 -0700, you wrote: <Snip> discussions <Snip> out <Snip> to <Snip> and <Snip> must <Snip> enlightenment <Snip> before. <Snip> ========================== ========================== ===== <Snip> ========================== ========================== ===== <Snip> unsvbscribes) go to =http://sweetmarias.com/maillistinfo.html#personalsettings========================== ========================== ===== Dave Morgenlender e-mail: dmorgen ========================== ========================== =====
My take is a bit different. Have you ever noticed the "bloom" that occurs when you pour water over freshly roasted and ground coffee? It has been years since I was exposed to organic chemistry, and quite honestly it was during a time of heavy experimentation, but it seems quite vividly to me that there is some sort of reaction going on there. This reaction diminishes in magnitude as the coffee stales. I will postulate that freshly roasted coffee must be in contact with elements that are common in air and water (hydrogen and/or oxygen?) in order to "rest" properly. At some point the coffee becomes "over-rested" and desirable flavors fade. Someone posted their simple solution to a quick rest that I have found suitable for my use and that was to grind the coffee and let it sit for some period before brewing.
On 4/19/07, Tom Ulmer wrote: <Snip> Tom, I have always *assumed* that the bloom was CO2 evolving from the grounds as the hot water infused and forced the CO2 out. The CO2 may be making an emulsion with the oils that are forced out as well giving us that foamy look to the bloom. CO2 is less soluble in hot water than in cold water, so I would expect it to come right out of the hot water. As time goes on, there is less bloom when you brew. I have always *assumed* that means the CO2 has already outgassed from the beans before we grind them with more time. I have always referred to "over-rested coffee" as "stale coffee". Safe Journeys and Sweet Music Justin Marquez (CYPRESS, TX)
It seems likely that carbon dioxide is a product of combustion. Is the assumption that roasting is a partial combustion which continues to produce carbon dioxide or that the carbon dioxide is somehow trapped in the roasted bean? Or is it perhaps another process altogether that I am failing to see?
I've always understood CO2 out gassing comes from CO2 trapped within the roasted beans cellular structure during the roast process being released. Don't ever recall reading (online or books) anything about CO2 continuing to be produced post roast, but have good not perfect recall so may be mistaken! Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Konnaisseur miKe mcKoffee URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must first not know. And in knowing know I know not. Each Personal enlightenment found exploring the many divergent foot steps of Those who have gone before. Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/ <Snip>
Might there a correlation between carbon dioxide out-gassing and proper rest interval? I typically leave the container lids open for the first 24-36 hours of rest as I prefer the flavors developed this way to beans sealed in containers soon after roasting.
From Sweet Maria's site:http://www.sweetmarias.com/roasting-VisualGuideV2.html------------------------------------------------------------------------------------------- *Full City Roast, Full City+ Roast** 415-425 degrees f. internal bean temperature, 438-448 f by thermo-probe This image represents a lighter Full City roast, where the coffee has just barely showed signs of 2nd crack -a snap or two-, or that 2nd crack is imminent, and the roast is stopped. The actual temperature that second crack normally occurs is higher: 446 degrees f internal bean temperature. But in fact second crack is a little less predictable than first crack, in my experience. Why? It could be explained as this: first crack is the physical expansion of the coffee seed as water and carbon dioxide split and CO-2 outgassing occurs. Second Crack is the physical fracturing of the cellular matrix of the coffee. This matrix is wood, also called cellulose, and consists of organized cellulose that reacts readily to heat, and not-so-organized cellulose that does not. Since every coffee is physically different in size and density due to the cultivar, origin, altitude, etc. it might make sense that the particular cell matrix is different too, and not as universally consistent in reactiveness as H-2O and CO-2. --------------------------------------------------------------------------------- Somewhere else (didn't ferret it out...) it tells that the CO2 produced is a result of the carmelization of sugars in the beans. Safe Journeys and Sweet Music Justin Marquez (CYPRESS, TX) On 4/19/07, Tom Ulmer wrote: <Snip>