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Fermenter Head Space, oxidation, and beer flavor

Post #1 made 12 years ago
by 2trout
Does the head space in the fermenter effect beer flavor? Does it cause oxidation and off flavors in beer?

I have not been worrying about this at all, should I be? How about on a long fermentation and lager?
"All I know is that the beer is good and people clamor for it. OK, it's free and that has something to do with it."
Bobbrews
    • BME Brewer With Over 5 Brews From United States of America

Post #2 made 12 years ago
by BobBrews
2trout,
Does the head space in the fermenter effect beer flavor? Does it cause oxidation and off flavors in beer?
The head space is filled with C02. As the yeast converts the sugars to beer they give off alcohol and C02. The C02 is heavier than air so it supplants the oxygen that was in the bucket. The blanket of C02 protects the beer and off flavors are not created. You can leave the beer in the bucket for six weeks with no problems.

I fill my kegs with C02 before filling so the beer that enters from a hose on the bottom stays under a blanket of C02. Cheers!
Last edited by BobBrews on 22 Jan 2013, 23:23, edited 2 times in total.
tap 1 Raspberry wine
tap 2 Bourbon Barrel Porter
tap 3 Czech Pilsner
tap 4 Triple IPA 11% ABV
Pipeline: Mulled Cider 10% ABV

http://cheesestradamus.com/ Brewers challenge!
    • SVA Brewer With Over 100 Brews From United States of America

Post #3 made 12 years ago
by GuingesRock
2trout, I ferment in the brew kettle with just a lid (admittedly only for 10 days) and haven't had a problem that I am aware of. The lid isn't sealed and the CO2 "burps" the lid. I have a big air space if I use my 16 gal pot. I went with fermenting in the brew kettle, based on similar stuff to what Bob just said.

I use leaf hops and leave them in for the ferment. There is a thick layer of Krausen leaf hop mix floating on the surface, which I wonder might also separate the beer from the air space.

Haven't done it any other way so can't compare.
Guinges

Post #4 made 12 years ago
by joshua
Good Day, I have read CO2 is heavier than air, so Soon as the fermentation breaths all the air, CO2 fills the FV, and will push the lid up, or bubbles the airlock.

IMHO
Honest Officer, I swear to Drunk, I am Not God.
    • SVA Brewer With Over 100 Brews From United States of America

Post #6 made 12 years ago
by GuingesRock
rdeselle wrote:Bob what do u use to put CO2 into the keg before filling?
Hi rdeselle. I expect Bob will answer but it is part of kegging to have a tank of CO2 to artificially carbonate the beer in the keg and to pressurise the keg for dispensing. The CO2 hooks onto the keg with a line and a quick connector.

Kegging was a complete mystery to me until I got into it two months ago. It’s pretty simple. Half an hour chatting to the girl in the home brew shop with the equipment in front of me, and I had all the information I needed to get started. I walked out with a tank of CO2 + pressure regulator, some brewery wash, some Starsan and a couple of beer lines with picnic taps on them, and two second hand Corny Kegs. It seemed like such a good idea that I couldn’t resist. Then I bought a freezer to keep the kegs in and cool the beer, and a temperature controller to keep the freezer at around +4C, then later I bought more kegs, and so on, and so on :)

“The difference between men and boys is the price of their toys” :)
Last edited by GuingesRock on 23 Jan 2013, 18:46, edited 2 times in total.
Guinges

Post #7 made 12 years ago
by kingdomofkeg
Open fermentation has a headspace as big as the room the fv is in and the co2 blanket still protects it. Seen a few vids on brewing tv where they just leave it open and let the wild yeast ferment the wort. Dont think il be trying it though.
The beer I had for breakfast was'nt bad so I had one more for dessert!

Post #8 made 12 years ago
by BobBrews
rdeselle.
Bob what do u use to put CO2 into the keg before filling?
In my kegging system I have a 4 keg distribution system. I can have four kegs on tap at the same time. When I set up my four way distribution system I also bought a Dual Gauge CO2 Regulator. I connected one of the regulator outputs to the 4 way distribution so that I can have all four kegs at one dispensing pressure. I connected the other regulator outputs to a single hose so that I can dial any pressure I want. This lets me Put a new keg on high pressure to carbonate or fill a keg with some StarSan and push the solution thru to clean a keg and cobra head hose. I use this for purging the oxygen from the keg before filling with beer.

I used a indelible marker to number each hose and valve. Zero (0) for the high pressure hose and 1 thru 4 for the combined pressure valves. It sure helps with the maintenance to know which valve to turn off or on! I also have a nitrogen tap so that I can do a proper Guinness!
Last edited by BobBrews on 23 Jan 2013, 20:58, edited 2 times in total.
tap 1 Raspberry wine
tap 2 Bourbon Barrel Porter
tap 3 Czech Pilsner
tap 4 Triple IPA 11% ABV
Pipeline: Mulled Cider 10% ABV

http://cheesestradamus.com/ Brewers challenge!
    • SVA Brewer With Over 100 Brews From United States of America

Post #9 made 12 years ago
by 2trout
Thanks for the answers guys.

It seemed to me that I had seen folks making a big deal about fermenting in glass and making sure that you filled the carboy close to the top.

I wont worry about it.
"All I know is that the beer is good and people clamor for it. OK, it's free and that has something to do with it."
Bobbrews
    • BME Brewer With Over 5 Brews From United States of America

Post #10 made 12 years ago
by BobBrews
2trout,

I don't do glass unless it's for mead and long term storage. I brew too much to trust not breaking glass. It's too heavy and dangerous for a klutz like me! Buckets are cheap, easy to clean, safe and reusable after their time is up. Glass and plastic are OK for anybody but me! People that make a big deal about using glass are glass owners. I don't care what people use as long as they are happy and brew good beer.
tap 1 Raspberry wine
tap 2 Bourbon Barrel Porter
tap 3 Czech Pilsner
tap 4 Triple IPA 11% ABV
Pipeline: Mulled Cider 10% ABV

http://cheesestradamus.com/ Brewers challenge!
    • SVA Brewer With Over 100 Brews From United States of America

Post #12 made 12 years ago
by BobBrews
rdeselle,

I am connecting the C02 gas to the gas in post on the keg. This just like your going to connect it regularly in the refrigerator. The gas connecters are sort of like putting air in a cars tires. You don't have a lever to push the connection opens the valve internally. The gas stays in the keg even though I don't have the top on. The gas will fill from the bottom and push the oxygen out of the open top. As long as the keg stays upright the oxygen can't get back in.

When I fill the keg the beer flows in from the plastic hose that I have cut to length. The beer is under the C02. As the beer fills the keg it pushes the C02 out of the keg. When the keg is full of beer I still should have 6 inches of C02 above the beer and then I seal it! The rest of the C02 is spilled on my floor. If I was to have a lit candle burning at the base of the keg the C02 spilling out of the keg would extinguish the flame!

I still purge the keg when I have a air tight seal by connecting the C02 and releasing the pressure relief valve on top of the cover. Hope I didn't confuse you more?

http://homepage.ntlworld.com/jim.dunleavy/cornelius.htm
corny2b.jpg
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Last edited by BobBrews on 24 Jan 2013, 21:39, edited 2 times in total.
tap 1 Raspberry wine
tap 2 Bourbon Barrel Porter
tap 3 Czech Pilsner
tap 4 Triple IPA 11% ABV
Pipeline: Mulled Cider 10% ABV

http://cheesestradamus.com/ Brewers challenge!
    • SVA Brewer With Over 100 Brews From United States of America

Post #13 made 12 years ago
by Hippy
BobBrews wrote:rdeselle,

I am connecting the C02 gas to the gas in post on the keg. This just like your going to connect it regularly in the refrigerator. The gas connecters are sort of like putting air in a cars tires. You don't have a lever to push the connection opens the valve internally. The gas stays in the keg even though I don't have the top on. The gas will fill from the bottom and push the oxygen out of the open top. As long as the keg stays upright the oxygen can't get back in.

When I fill the keg the beer flows in from the plastic hose that I have cut to length. The beer is under the C02. As the beer fills the keg it pushes the C02 out of the keg. When the keg is full of beer I still should have 6 inches of C02 above the beer and then I seal it! The rest of the C02 is spilled on my floor. If I was to have a lit candle burning at the base of the keg the C02 spilling out of the keg would extinguish the flame!

I still purge the keg when I have a air tight seal by connecting the C02 and releasing the pressure relief valve on top of the cover. Hope I didn't confuse you more?

http://homepage.ntlworld.com/jim.dunleavy/cornelius.htm
corny2b.jpg
Bob how long do you run the gas into the keg to fill it up? As CO2 is heavier than air and displaces it, would it work if you just gave a quick burst to create a blanket of CO2 over the beer as it is poured into the keg?
Last edited by Hippy on 27 Jan 2013, 16:07, edited 2 times in total.

Post #14 made 12 years ago
by BobBrews
Hippy,

Since I use a (sanitized) plastic tube that extends from the valve of my fermenting bucket to the bottom of the corny keg. (Technically) I only need a inch or so because as the beer comes from under the layer of C02 and as the beer rises the layer of C02 rises on top of the beer. In reality I give about 5 seconds of C02 at the gas in post. More than enough! (for me) C02 is cheap. $5 a fill. About the same as a Starbucks coffee?

When the keg fills with beer I am sure than C02 pours out of the top anyway? After the lid is in place I spray the lid with a mixture of StarSan and water to look for leaks. I use a spay bottle from something non toxic.

I still "purge" the keg which is probably not necessary, out of habit. That means I pressurize the keg and pull the pressure release valve. I do it at least twice. The reason for doing this is "If" the keg has 100 percent oxygen in it and you pressurizes with C02 it should be 50-50 percent. so I pull the valve and let the pressure out. I fill again which means the "now" 50-50 mixture will 75-25? (I don't know the math) So I pull it again! Each time until the C02 is purged out! :scratch:
tap 1 Raspberry wine
tap 2 Bourbon Barrel Porter
tap 3 Czech Pilsner
tap 4 Triple IPA 11% ABV
Pipeline: Mulled Cider 10% ABV

http://cheesestradamus.com/ Brewers challenge!
    • SVA Brewer With Over 100 Brews From United States of America

Post #15 made 12 years ago
by Hippy
Thanks Bob.
That's pretty much what I had pictured.
Will have to start filling with the CO2 blanket myself as the rest of your method is the same as what I do and it makes sense to start with a short blast of CO2 as well.

Post #16 made 12 years ago
by HbgBill
As a point off topic to the OP. Headspace in the FV doesn't make any difference.. Many German breweries have totally uncovered FV's However, IF you rack to a SECONDARY, the headspace can certainly make a difference as there is little/no active fermentation going on and there will be too much air (containing O2) in the headspace that can cause oxidation. This is where Bob's kegging setup works well. I rarely rack to a secondary.. but if I do a 4G batch and only have a 5G carboy.. I purge it with CO2 and let the siphon rip. Then, for safety sake.. do a final purge before putting in the stopper. Can't be too careful after all that work and money :)
Bill
Hop Song Brewing-Santa Rosa, California

Post #17 made 12 years ago
by Hippy
I agree with you there HbgBill. I have two fermenters containing lagers in my fridge which I'm about to rack and CC at -2 for a couple of weeks. I'd hate to have wasted a month on oxidised cat's piss. Especially when you consider lower temps increase the solubility of gases in a liquid.
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