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Old 03-27-2012, 07:48 PM   #41
MalFet
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Quote:
Originally Posted by Kealia View Post
Ummmm....gas.

All kidding aside, it's a grey-ish gas that hangs out at the bottom of the keg. Maybe it has something to do with the temp difference, the StarSan or something else but after hooking up an empty keg, blasting it with CO2, purging the air and then removing the lid it hangs out down at the bottom.

Or maybe I'm high....
Weird...I've never seen that. Maybe it has something to do with temperature, as PVH suggested. Is your tank in the fridge? In general CO2 is colorless.

In any case, your post inspired me to do some home science. I took a corny and ran it through four pressure/purge cycles to make sure the contents were as close to pure CO2 as I could get. Right after opening it, I stuck a lighter in and it immediately went out. Then I sealed it up again, did the pressure/purge thing again, opened it. After twenty minutes, the lighter still went out, albeit more slowly. After an hour, it stayed lit.

In open fermentation, I've got to imagine the CO2 would blow off as fast as it could be made. Even in the couple inches of headspace provided by a standard ale pail, my hunch is that the CO2 would get disrupted by whatever turbulence is created while futzing with the beer. The CO2 blanket doesn't stick around for long in an open environment. Brownian motion FTW!
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Old 03-27-2012, 07:54 PM   #42
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Originally Posted by MalFet View Post
Weird...I've never seen that. Maybe it has something to do with temperature, as PVH suggested. Is your tank in the fridge? In general CO2 is colorless.
My tank is outside the fridge. If I connect a gas in with the corny lid off and put CO2 in, it is invisible. If I do that with the lid on, release pressure, and then take the lid off, I get the same "gas haze" effect, it is smoky or misty. I will let more knowledgeable folks ponder on it, but I think it has something to do with pressurization and sudden release in a moist keg (this is usually after a water or star-san rinse).

 
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Old 03-27-2012, 08:34 PM   #43
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I thought it might be either a temp thing or moisture....interesting. I think it's cool that you grabbed a match and put this to the test, too!

Interesting feedback and input. So I guess the notion of a "blanket" of CO2 only really applies to a closed fermentation.

In the open fermentation videos I've seen they always scrape off the krausen for the first few days anyway. It must be the krausen that provides the barrier and anything that gets caught there gets scraped off anyway. That would explain how the yeast get more exposure to oxygen.

Interesting discussion...

 
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Old 03-28-2012, 12:03 AM   #44
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There are many breweries that do open fermentations in New York. There's 2 that are Ringwood breweries (Cooperstown and Davidson Brothers) and they skim the yeast right off the top to use for the next batch. Also, Ommegang uses open fermentations. Now all of these people transfer the beer into bright tanks as soon as fermentation is over. I'm also confused because I was under the impression that open fermentation was supposed to encourage more esters not less.

 
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Old 03-28-2012, 12:23 AM   #45
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Originally Posted by JonGrafto

A bit Fuzzy? Your memory or the beer?
Lol! Sorry , I meant the memory...

 
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Old 03-28-2012, 01:13 AM   #46
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Anyone ever try kellerweiss by sierra nevada? That's open fermented and there are tons of banana and clove esters, more so than any other hefeweizens i've ever had

 
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Old 03-28-2012, 01:20 AM   #47
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Anyone ever try kellerweiss by sierra nevada? That's open fermented and there are tons of banana and clove esters, more so than any other hefeweizens i've ever had
I actually started harvesting the yeast from a bottle of kellerweiss once, but never finished it. It got old and I recently dumped it. I'm still not even sure if it was fermentation or bottling yeast...
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Old 03-28-2012, 02:46 AM   #48
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Quote:
Originally Posted by bwomp313 View Post
There are many breweries that do open fermentations in New York. There's 2 that are Ringwood breweries (Cooperstown and Davidson Brothers) and they skim the yeast right off the top to use for the next batch. Also, Ommegang uses open fermentations. Now all of these people transfer the beer into bright tanks as soon as fermentation is over. I'm also confused because I was under the impression that open fermentation was supposed to encourage more esters not less.
You're right bwomp313. Open fermentations have been proven to give more esters in the final product at least an excerpt from Stan Hieronymus' book Brewing with Wheat claims it does. Here's an excerpt:

"As with other brewing research, studies involving fermenter geometry have focused on lager beers. Ester production by yeast is inversely related to yeast growth, but research by Greg Caseyat Coors has shown this relationship can be uncoupled by fermenter design. Casey presented his findings at the 2005 Rocky Mountain Microbrewing Symposium. In simplest terms, when CO2 levels increase around the yeast in the fermenter, the levels of ester production decrease. For instance, when some breweries replaced box fermenters with cylindro-conicals they found the greater height-to-width ratio reduced ester character. The change was more pronounced in taller, "skinnier" fermenters-something homebrewers using Cornelius kegs as fermenters might want to rembember....."

 
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Old 03-28-2012, 03:10 AM   #49
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Quote:
Originally Posted by dragonbreath11

You're right bwomp313. Open fermentations have been proven to give more esters in the final product at least an excerpt from Stan Hieronymus' book Brewing with Wheat claims it does. Here's an excerpt:

"As with other brewing research, studies involving fermenter geometry have focused on lager beers. Ester production by yeast is inversely related to yeast growth, but research by Greg Caseyat Coors has shown this relationship can be uncoupled by fermenter design. Casey presented his findings at the 2005 Rocky Mountain Microbrewing Symposium. In simplest terms, when CO2 levels increase around the yeast in the fermenter, the levels of ester production decrease. For instance, when some breweries replaced box fermenters with cylindro-conicals they found the greater height-to-width ratio reduced ester character. The change was more pronounced in taller, "skinnier" fermenters-something homebrewers using Cornelius kegs as fermenters might want to rembember....."
Esters contain two atoms of oxygen, so doing an open fermentation and also maximizing the surface area of the wort to atmospheric oxygen with a very wide vessel would encourage ester formation by allowing plenty of oxygen to be present. CO2 is a terminal product, its oxygen can't be used to create esters. This all makes perfect sense.

Sorry, I just finished a 750ml bottle of homebrew.

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Old 04-01-2012, 12:34 AM   #50
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Well to give an update. I kegged the batch that was open fermented for exactly 1 week at 55F using wlp002 and overnight mashed for 12 hours. No pellices or sour flavor of any kind though. My hygiene was very good. No butterscotch to my surprise, I kinda expected some Diacetyl at these temps. An uncarbonated sample tasted similar to Dogfish Brown, nice roasty character which was surprising since only 2.6oz of chocolate malt was used. I think the longer the mash the more malt flavor is extracted into the final product. Most likely conversion takes place in 20-45min but I think mashing longer extracts more flavor from the malt than doing short mashes. Anyway, 3 more weeks til the first pour of Madness Brown.

p.s. It's so much easier washing and hauling stainless steel brewpots used in fermentations than carboys. I may have to retire the carboys for awhile.

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