Avoiding suckback when cold crashing?

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drksky

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I was wondering, what if, instead of dropping the temperature while the beer is still in the fermenter, you transfer to a corny with gelatin, purge and pressurize then drop the temperature.

Since the keg is sealed, there's nothing to suck back with the pressure change and I'm guessing that cornies have enough strength to withstand any vacuum being generated.

Thoughts/discussion?
 

DemonsRun

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I do most of my small batch fermenting in corny Kegs, I usually put the lid on Purge with a bit of CO2 then cold crash. Yes they can withstand the pressure change, but I usually add a bit of pressure.

I also do something similar with my larger Speidel fermenters. Swap out the airlock for the cap w/plastic spout and pressurize slightly, then cold crash.
 

kev211

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Well if you're pressurizing the keg then you shouldnt have to worry about any negative pressure (especially if you keep the CO2 on the whole time). I dont cold crash in the fermenter anymore. I transfer to keg (without gelatin), purge, and toss in the kegerator. Beers come out super clear.

Only adjustment Ive made is, I cut about 1/4" off the liquid out dip tube to avoid sucking up any more yeast/trub. Dont lose more than half a pint and everything runs great (no clogged poppets/posts)
 

jddevinn

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I'd add some CO2 pressure. If you develop a vacuum in the keg I wouldn't see it hurting it.... but I would expect the lid to leak.

I've stopped using gelatin all together due to oxidation and see no difference in beer clarity after about a week.
 

derekcw83

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I've always wondered about just gradually lowering temperature, not sure however if there would be enough co2 being produced to counter the vacuum. Plus this requires a dedicated fridge to gradually drop temp over the course of a few days to a week.
 
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drksky

drksky

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I'd add some CO2 pressure. If you develop a vacuum in the keg I wouldn't see it hurting it.... but I would expect the lid to leak.

I've stopped using gelatin all together due to oxidation and see no difference in beer clarity after about a week.
Curious how gelatin introduced oxidation?
 

jddevinn

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Packaged O2 concentration should be remarkably low, less than 2ppm. If the water used in the gelatin wasn't degassed completely it contains O2. Standard procedure for gelatin involves boiling water to sanitize then letting it cool, letting the gelatin "bloom" at a warm temp. While the water/gelatin sits there blooming for an hour it picks back up O2 that is then added to the beer.

If you're not closed system fermenting, closed transferring, properly purging kegs, extra it's not going to matter. But if you avoid oxidation at all the other steps adding gelatin with dissolved oxygen in the water can push way above 2ppm. In the end the beer is clear without it.
 

mbbransc

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I cold crash in a conical with CO2 at ~4psi. I add gelatin to my keg (and any dry hops, if warranted) prior to purging. Then use the CO2 to rack to the keg. Best of both worlds.

Regarding the no difference between gel'd beer and un-gel'd beer, I can only assume you didn't do something right. The difference is stark. If it's a beer that's going to sit more than a month, maybe it doesn't matter as much. But with gelatin, I can have nearly brilliantly clear beer in about 2-days... if it's important.
 

jddevinn

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I cold crash in a conical with CO2 at ~4psi. I add gelatin to my keg (and any dry hops, if warranted) prior to purging. Then use the CO2 to rack to the keg. Best of both worlds.

Regarding the no difference between gel'd beer and un-gel'd beer, I can only assume you didn't do something right. The difference is stark. If it's a beer that's going to sit more than a month, maybe it doesn't matter as much. But with gelatin, I can have nearly brilliantly clear beer in about 2-days... if it's important.
Left beer is leaving the brite tank, so maybe a week at 32°F after transferring from the fermenter. Right beer is going from fermenter to brite. Don't think I'm doing anything wrong.:tank:

How are you adding gelatin and dry hops to the keg before purging? Unless you are purging 20+ times at ~30psi or filling the keg with a liquid then pushing the liquid out you have way above recommended O2 remaining in the keg.

2015-11-25 14.18.19.jpg
 

brewbama

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Packaged O2 concentration should be remarkably low, less than 2ppm. If the water used in the gelatin wasn't degassed completely it contains O2. Standard procedure for gelatin involves boiling water to sanitize then letting it cool, letting the gelatin "bloom" at a warm temp. While the water/gelatin sits there blooming for an hour it picks back up O2 that is then added to the beer.

If you're not closed system fermenting, closed transferring, properly purging kegs, extra it's not going to matter. But if you avoid oxidation at all the other steps adding gelatin with dissolved oxygen in the water can push way above 2ppm. In the end the beer is clear without it.

I fine with gelatin and never have oxidation. 2/3 cup water w/1 tsp gelatin in 5 gal beer. What you described is not my "Standard procedure". I do this:

http://www.bertusbrewery.com/2012/06/how-to-clear-your-beer-with-gelatin.html

I rack from fermenter to keg, purge the headspace, cold crash for a cpl daze, add gelatin, purge the headspace, put it on CO2 and drink crystal clear beer in a cpl daze. Except w/K97. It takes a while to clear.

View attachment ImageUploadedByHome Brew1470784201.788597.jpg

Cheers!
 

jddevinn

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No to berate anyone's processes but since I got asked the question.

Assuming all your other cold side processes are 100% oxygen free (they are far from it with your purging methods).

  • water at ~150°F has a dissolved oxygen concentration of approximately 5.6ppm
  • 2/3 cups water at 5.6ppm into 5 gallons of COMPLETELY oxygen free beer results in a concentration of 0.053ppm O2
  • Target total dissolved oxygen in packaged beer is <0.2ppm (Brewing Science and Practice, and Kunze)
  • To achieve <0.2ppm total the oxygen uptake during packaging should be less than 0.03ppm, the O2 in the gelatin exceed the specification already

You may not taste the difference, you may be used to adding excess hops to compensate for their quick fading, you may not keep your beer around long enough to oxidation notice effects... But it is EXTREMELY easy to oxidize beer post fermentation, especially when kegging.
 

55x11

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  • To achieve <0.2ppm total the oxygen uptake during packaging should be less than 0.03ppm, the O2 in the gelatin exceed the specification already
I follow your logic until the last part. how did you get from 0.2ppm to .03ppm?

Also, out of curiosity, what is your procedure for flushing the keg/lines and transferring beer from fermentor to keg - are you sure it results in less than 0.2ppm oxygen uptake?

finally, doesn't yeast (whatever is left in the keg - and it's plenty, since unlike professional breweries we don't filter or pasteurize usually) scavenge these tiny amount of oxygen anyways?
 

mbbransc

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Left beer is leaving the brite tank, so maybe a week at 32°F after transferring from the fermenter. Right beer is going from fermenter to brite. Don't think I'm doing anything wrong.:tank:



How are you adding gelatin and dry hops to the keg before purging? Unless you are purging 20+ times at ~30psi or filling the keg with a liquid then pushing the liquid out you have way above recommended O2 remaining in the keg.

I flush the keg with sanitizer to fully purge the keg. I attach my hop sack to a second keg lid and quickly swap lids. I'm sure small amount of O2 is entering the keg but honestly, it's even overkill for what I need. It's not like I'm looking for shelf stability. The keg won't last a month anyway. Only reason I go this far overboard is in case I'm interested in entering a contest and it may need to stay fresh a little longer. I have enough blue ribbons to feel confident in my processes.

I brew 10gal batches of IPA. I recently gel'd one keg and not the other. I brew NEIPAs. One was cloudy as expected and the other was nearly clear. I posted pics on some FB groups. I'll look for them tomorrow to post.
 

jddevinn

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I follow your logic until the last part. how did you get from 0.2ppm to .03ppm?

Also, out of curiosity, what is your procedure for flushing the keg/lines and transferring beer from fermentor to keg - are you sure it results in less than 0.2ppm oxygen uptake?

finally, doesn't yeast (whatever is left in the keg - and it's plenty, since unlike professional breweries we don't filter or pasteurize usually) scavenge these tiny amount of oxygen anyways?
Recommendations are to keep less than 0.03ppm uptake at packaging (bottling, canning, kegging) to be able to achieve the <0.20ppm goal.

I'm SURE of nothing as I have been unable to find a DO meter that is good for this application in a reasonable price range. What yeast is left over (I have very little to no visible yeast) will scavenge the O2 remaining ONLY if there are fermentables remaining. Bottlers get a little leeway here. The typical "off" flavors and instability that comes from oxidation is the end of a multistep reaction though, as the yeast are scavenging the O2 (if there are fermentables) the O2 is reacting to create the preceptors that we want to avoid.

My ever changing and (hopefully improving) kegging setup is:

  1. Cold crash in conical under CO2 pressure
  2. purge kegs by filling with StarSan solution
  3. sloshing to remove air bubbles from the top out the dip in as much as possible
  4. Push StarSan solution from one keg to another
  5. for 10 gallon batches hook the OUT from one keg to the IN from the first keg
  6. connect a keg QDC to a length of hose ending in a triclamp connection
  7. sanitize the triclamp racking port of the fermenter
  8. submerge the QDC, hose and triclamp in StarSan so that the tubing is full
  9. hook the QDC to the pressurised keg, (hopefully) pointing the triclamp into the bucket of StarSan
  10. Star san will shoot out of the tubing, with ~30-40 seconds of CO2 following
  11. connect the triclamp to the fermenter while the CO2 is coming out of the tube
  12. hook a QDC to the second keg IN with the end of the hose submerged in Starsan
  13. open fermenter racking valve, CO2 pressure will begin filling the fist keg
  14. once the first keg is full the second keg will start to fill

Of course these recommendation levels are for commercial breweries. Pasteurization has effects that very dependent on the DO. Commercial breweries also target longer shelf lives than MANY homebrewers.

2016-08-07 00.06.33.jpg
 

55x11

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Recommendations are to keep less than 0.03ppm uptake at packaging (bottling, canning, kegging) to be able to achieve the <0.20ppm goal.

I'm SURE of nothing as I have been unable to find a DO meter that is good for this application in a reasonable price range. What yeast is left over (I have very little to no visible yeast) will scavenge the O2 remaining ONLY if there are fermentables remaining. Bottlers get a little leeway here. The typical "off" flavors and instability that comes from oxidation is the end of a multistep reaction though, as the yeast are scavenging the O2 (if there are fermentables) the O2 is reacting to create the preceptors that we want to avoid.

My ever changing and (hopefully improving) kegging setup is:

  1. Cold crash in conical under CO2 pressure
  2. purge kegs by filling with StarSan solution
  3. sloshing to remove air bubbles from the top out the dip in as much as possible
  4. Push StarSan solution from one keg to another
  5. for 10 gallon batches hook the OUT from one keg to the IN from the first keg
  6. connect a keg QDC to a length of hose ending in a triclamp connection
  7. sanitize the triclamp racking port of the fermenter
  8. submerge the QDC, hose and triclamp in StarSan so that the tubing is full
  9. hook the QDC to the pressurised keg, (hopefully) pointing the triclamp into the bucket of StarSan
  10. Star san will shoot out of the tubing, with ~30-40 seconds of CO2 following
  11. connect the triclamp to the fermenter while the CO2 is coming out of the tube
  12. hook a QDC to the second keg IN with the end of the hose submerged in Starsan
  13. open fermenter racking valve, CO2 pressure will begin filling the fist keg
  14. once the first keg is full the second keg will start to fill

Of course these recommendation levels are for commercial breweries. Pasteurization has effects that very dependent on the DO. Commercial breweries also target longer shelf lives than MANY homebrewers.
My process is similar to yours but I have some work to do to get to your level.
I cold-crash in fermentor but I flush it and it's connected to a large empty PET fermentor (or keg) filled with CO2 under low pressure (a few psi). that usually is sufficient to keep oxygen from entering or PET container collapsing.

But I feel like .03 ppm is a bit of unrealistic goal. That's about 0.5 cubic centimeter (or 0.5 mL) of oxygen per 5 Gallons, if I am not mistaken. If I don't empty all the starsan from the keg during purge, or don't fill the keg to the top and fail to purge >10 times, or have an air bubble inside one of the connectors or inside the transfer line (I assume you fill it completely with beer before transfer) - I can easily get that 0.5 cu cm (or 0.5 mL) of air.

Even if I can push all starsan (without leaving a quarter of a cup on the walls and at the bottom - and at room temperature oxygen is more soluble), while starsan was being emptied, it was outgassing oxygen into the keg, right?

at 8 ppm solubility and 5 Gallons of starsan, containing 152 mg of oxygen dissolved in it - and we can supposedly tolerate less than 1mg, so while we are emptying starsan, aren't we also letting oxygen precipitate and enter the headspace?

I am trying to be careful about oxygen like you, but I wonder if we are overthinking it a bit by setting a somewhat unrealistic goal/limit.
 

jddevinn

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I'm sure that I am not hitting the goal that I'm aiming for and it is likely unrealistic. However, while I would say I and my friends are "heavy drinkers" with 10 rotating taps it is not uncommon for a keg to sit for 6 months before it is finished so I am trying for stability. Since many of my kegs sit anyway I find no need for the gelatin anymore.... I also find a 2-3 week lager time improves EVERY beer style I've made, even 2-3xIPA's

I try to purge all of the transfer lines by filling them with StarSan and pushing it out with CO2 from the pressurized keg.

Left off a step from my process... I normally clean and "purge" a batch of 4-8 kegs at a time. When I make the StarSan solution I preboil the water in my HLT then rapidly cool with the HERMS coil to reduce the O2 concentration and add a Campden tablet. When it is pushed keg to keg yes it does pick up O2 so that the last keg is "less purged" than the first. I have thought about adding (additional) SMB to help limit O2 uptake but haven't done so yet.
 
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