Taking the plunge. Open Fermentation. Yes I'm willing to dump a batch.

[Kealia]

On another board a member is trying this using WLP300 after watching a Brew TV episode, too. They claim the get MORE esters through an open fermentation but here's what I don't get:

We all know/agree that during primary fermentation that a layer of CO2 will form a protective barrier for the wort, keeping oxygen out. But the claim is that more oxygen is better for the yeast, they are less stressed and then produce more esters.

What I have trouble comprehending is how you can have it both ways? A protective barrier keeping the oxygen out AND having more oxygen for the yeast.

Somebody 'splain please.

 

[dragonbreath11]

On another board a member is trying this using WLP300 after watching a Brew TV episode, too. They claim the get MORE esters through an open fermentation but here's what I don't get:

We all know/agree that during primary fermentation that a layer of CO2 will form a protective barrier for the wort, keeping oxygen out. But the claim is that more oxygen is better for the yeast, they are less stressed and then produce more esters.

What I have trouble comprehending is how you can have it both ways? A protective barrier keeping the oxygen out AND having more oxygen for the yeast.

Somebody 'splain please.

I'm perplexed by this myself.

 

[MalFet]

On another board a member is trying this using WLP300 after watching a Brew TV episode, too. They claim the get MORE esters through an open fermentation but here's what I don't get:

We all know/agree that during primary fermentation that a layer of CO2 will form a protective barrier for the wort, keeping oxygen out. But the claim is that more oxygen is better for the yeast, they are less stressed and then produce more esters.

What I have trouble comprehending is how you can have it both ways? A protective barrier keeping the oxygen out AND having more oxygen for the yeast.

Somebody 'splain please.

I think this notion of a "protective layer" is something of a brewing urban legend. Certainly fermentation in containers sealed with a valve/airlock will displace the oxygen to create an (almost) pure CO2 headspace, but that doesn't apply in open containers. Open fermentation should give you plenty of oxygen.

 

[JonGrafto]

My uncle used to open ferment german lagers in his basement, in square terra cotta fermenters , covered with cheesecloth, set directly on the concrete floor. I don't think he had any issues with infection, but that's way back..a bit fuzzy.

A bit Fuzzy? Your memory or the beer?

 

[Kealia]

I dunno....I've played with my keg a bit by blasting it with CO2 and purging the air, then removing the top (with it empty, mind you) and the CO2 does sit nice and low and provide a barrier.

BUT, that's in a tall cylindrical environment so I assume a bucket/ale pale would be similar. In the video on Brewing TV (IIRC) they use a fish cleaning table that is flat and low so I wouldn't expect the same rules to apply there - but a bucket, yes.

 

[MalFet]

I dunno....I've played with my keg a bit by blasting it with CO2 and purging the air, then removing the top (with it empty, mind you) and the CO2 does sit nice and low and provide a barrier.

BUT, that's in a tall cylindrical environment so I assume a bucket/ale pale would be similar. In the video on Brewing TV (IIRC) they use a fish cleaning table that is flat and low so I wouldn't expect the same rules to apply there - but a bucket, yes.

How do you know the CO2 stayed put?

 

[Kealia]

Visually. There's a nice layer of gas visible even after taking off the lid and checking it much later.

 

[MalFet]

Visually. There's a nice layer of gas visible even after taking off the lid and checking it much later.

Hmm...carbon dioxide has always been very much invisible to my eye. What exactly are you seeing?

 

[Kealia]

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....

 

[PVH]

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....

I get the same thing. I figure it's condensation from rapidly reducing the temp in the keg. My CO2 tank is in the beer fridge, and the empty kegs are at room temp.

 

[MalFet]

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!

 

[dbrewski]

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).

 

[Kealia]

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...

 

[bwomp313]

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.

 

[erikhild59]

A bit Fuzzy? Your memory or the beer?

Lol! Sorry , I meant the memory...

 

[CidCitrus]

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

 

[Stauffbier]

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...

 

[dragonbreath11]

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....."

 

[JimTheHick]

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.

 

[dragonbreath11]

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.

 

[triskelion]

how'd it turn out?

 

[Kealia]

Mine turned out fine. The open fermentation worked well, no issues.

I can't say that is was better or worse than my precious hefs because I had to use Wyeast versus the WL that I ususally used and I had poor temp control so I can't call it a true test. I do plan on doing it again when the weather warms up a bit and I can keep it at 70 - 72, though.

 

[DonLiguori]

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.

I'm not so sure about this, it may be more of a negative feedback response from the carbon dioxide in the finishing beer pressuring the yeast to stop whatever metabolic pathway produces the esters in the first place. Esters form from a carboxylic acid and an alcohol undergoing a condensation reaction. The oxygen itself in the beer/wort wouldn't really be responsible at all for this unless the yeast are fixing the oxygen in some sort of carboxylic acid cycle. I'll look into that and see what we come up with!