Preventing oxidation

How much of a risk of oxidation is there when taking gravity samples or adding dry hops? Does oxygen just swoop in once you remove the airlock? Since I don’t have the capability to inject co2 into carboys yet…would it be feasible to light a long match and stick it in the carboy to scavenge oxygen? Thanks!

It can be a very real concern. You aren’t going to turn your beer into wet cardboard by opening it up, but it doesn’t take much oxygen to ruin the fresh hop aroma and flavor in an IPA. If you notice your IPA flavor just dies after a few weeks in the bottle, that’s oxidation.

Something you can do to help avoid this is dry hop just as active fermentation is dying down. This lets the yeast scrub out oxygen that’s being introduced. It goes against conventional wisdom, but for someone that bottles it can really help. Plus, some yeasts can release aromatic hop compounds that are otherwise lost. But if your beer isn’t relying on massive hop aroma and flavor, it really isn’t a big concern to avoid small amounts of O2.

Rather than trying to burn a match inside your carboy, if you want an easy way to purge oxygen, add a few ounces of club soda to your beer. This will push out any oxygen that makes its way in.

I would say there is very little risk of oxidation unless you slosh the beer around in the fermentor. The largest concentration of CO2 over the top of the beer is during active fermentation when CO2 is being produced. After fermentation some CO2 is present while it comes out of solution. During this time atmospheric air is entering the fermentor even with an airlock installed. Gases in the environment inside and outside the fermentor will reach equilibrium unless the fermentor is sealed. Changes in barometric pressure and temperature changes can act like a pump to aid the equilibrium being reached through the airlock. Atmospheric air doesn’t get pumped into the beer though. It is just present above the surface. Eventually the atmospheric air will affect the beer, but it will take longer than we typically leave beer in the fermentor even for an extended primary time.

Splashing while adding hops can introduce oxygen into the beer. Splashing is easy to avoid though just by pouring in pellet hops instead of throwing the hops in. Whole hops, and pellets, will stay on the surface until they absorb beer and sink. During the absorption process air is forced out at the surface into the fermentors environment over the beer rather than into the beer. Dropping a weighted bag of hops into the beer will draw oxygen down into the ber as it rapidly drops. Most of the air in the bag will rise to the surface as bubbles rather than being absorbed into the beer. There is greater risk of some oxidation from dropping a weighted bag into the beer than pouring pellets on to the surface.

Same with drawing a SG sample. Without a lot of splashing very little risk of oxidation.

Will the oxidation be noticeable? I don’t think so. I think you really need to slosh the beer or let it splash from the end of a siphon tube to cause noticeable oxidation.

Just my opinion.

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I soak my hop bag and weight in starsan shake it out then add the hops pellets and squeeze out the air, then lower it in the fermenter. I do it after the krausen starts to drop but fermentation is not completely done. Don’t leave the top off the fermenter for any lengths of time and the co2 is heavier than air so it’s not coming out. The biggest chance of origination comes when racking. But again good technique will mitigate that. As long as your not sloppy oxigination is not a problem.

So when using a bucket, wouldn’t you want to make the air locker hole bigger to accept the stopper we use for a carboy? Then you wouldn’t need to remove the lid, you can pull yer sample through the hole with a wine thief and carefully add yer hops also. Minimizing the risk is what needs to be the equation… Sneezles61

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Good idea! I would try it first with a similar junker bucket lid just to make sure the drilled bung will hold. Don’t see any reason that it wouldn’t though.

CO2, being heavier than the rest of the air will tend to sink, unless you mix the air, say by wafting the bucket lid too much. Be gentile, avoid splashing as others have said and RDWHAHB.

I’ve had a problem at the opposite extreme. I had a small blow-off issue, and almost passed out as I was reaching into the chest freezer to clean it up. An active fermentation can easily displace all the oxygen in a medium sized chest freezer.

No problem, I just pop the lid with one of those lid tools. Slide the top over an inch of so and grab a sample using a turkey blaster then slide the top back over. Same for additions. The lid never comes off even when racking. You would really have to try hard to get the o2 to displace the co2. Remember your physics. Heck I don’t even use a stopper when fermenting in my freezer.

So along the thoughts of this forum: Do you guys think you risk oxidation when/if you transfer your brew from the fermentor to a bottling bucket? I’ve been transferring to a bucket to mix with the priming sugar and after reading everyones’ comments I’m worried I may be oxidizing the beer when I bottle it. Also, if I am, how would you prevent it? Not trying to highjack the thread just curious since we are talking about oxidation prevention.

Yes, there is some risk of oxidation during the transfer. For me the risk is necessary because bottling from the fermentor with a siphon just seems like to big of a hassle. I do make sure the outflow end of the siphon tube is curled around the bottom of the bucket and lays flat to avoid any splashing. Splashing will expose more surface area to the air and force air into the beer. I lodge the end of the siphon tube under the buckets valve assembly to keep it in place. The surface of the beer in the bottling bucket is exposed to the air, but it is fairly short term exposure during the time it takes to bottle. In this short time I don’t think enough air can enter the beer to begin the oxidation process.

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I figure the little bit of oxygen is needed for the yeast to get active for the bottle fermentation to carbonate.

Yes, you definitely introduce some oxygen in the bottling bucket. Whether it’s going to affect the beer is a different matter, though. In general, you aren’t going to create the classic cardboard/sherry flavors if you carefully rack the beer without splashing, although this may show up after years of storage. But the small amount of oxygen introduced is enough to cause rapid degradation of highly hopped beers. Ever tasted a commercial IPA that was mostly just bitter with kind of a caramelly off flavor? That’s what small amounts of oxygen do to an IPA after a few weeks.

For almost every other style, though, it isn’t going to have any significant affect.

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Do as suggested by others and make sure your siphon hose reaches the bottom and is quickly covered to reduce splashing. I am convinced that paying just a little bit more for oxygen absorbing bottle caps is a great way to help eliminate the small amount of oxygen you will pick up through the bottling bucket transfer.

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That’s a good point, because whenever you bottle with an appropriate amount of headspace, there is oxygen that is captured inside the bottle. As the beer carbonates, that oxygen will be forced into the beer, creating the opportunity for oxidation. The yeast may utilize it, or it may result in slight oxidation of your beer. So it goes beyond just what you get in the bottling bucket, as you’re trapping some oxygen inside the bottle.

Just a side note, if you place a cap on top of a filled bottle without crimping it, you’ll hear the bottle “burp” a few times as it sits. If you wait a few minutes, the disturbance of filling the bottle knocks some of the CO2 out of suspension, displacing the oxygen in the bottle headspace. Not sure how much of a difference it makes, but I usually wait 5 minutes or so before crimping caps.


The chance of oxidation from the examples you give is just over zero…meaning virtually no chance. Don’t sweat it, don’t go crazy,

For most styles of beer, yes I would agree with that. For highly hopped IPAs and mixed fermentation wild/sour beers, I would not agree.

I’m not specifically talking about the type of oxidation that results in your beer tasting like cardboard, but the kind that robs your fresh hop aroma after a few weeks in the bottle. I’ve been fighting this for quite awhile, and if anything were to make me start kegging, it would be shelf life of hoppy beers. Some of the best homebrewed IPA examples were from homebrewers who went a little crazy, transferring only by pushing with CO2, purging kegs and bottles, capping on foam, etc. Everything with the intent of preventing oxygen from touching the beer. The shelf life of these beers is incredible compared to ones I have bottled.

Also, there’s nothing worse than spending a couple years on a nice fruited sour, getting the flavor just where you want it, bottling and conditioning it for a couple months, and having it taste like a mouse has been sleeping in your fruity pebbles. (being generous with that description, too!) :scream:

Sure, that’s bad, but it ain’t gonna happen by opening the fermenter to take a gravity reading.

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Oh, absolutely! Very little risk in grabbing a thief-full of beer or adding dry hops. My comment was more in regard to @HBC’s comment about exposure in the bottling bucket. In my opinion, open-system transfers and bottling are the two areas most likely to introduce oxygen post-fermentation. Also, @jdwilliam’s suggestion to use oxygen-absorbing caps are a great idea for styles that are more sensitive to oxygen degradation.

Some things that I’ve done to oxidize my beer include:
-Getting the inlet to the auto-siphon clogged with hops/trub and sucking in air past the grommet.
-Pulling up to quickly on the auto-siphon and jerking the outlet of the tube out from the bottom of the bucket, creating copious amounts of splashing.
-Old worn valve on bottling bucket sucking air in between the two rotating bodies.
-Forgetting to add priming sugar, not realizing it until I’ve filled 6 or so bottles and having to pour them back.

I’m sure there’s more, I’ve found quite a few creative ways to damage my beer. :sweat_smile:

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I have now done 495 batches by xferring to an open bottling bucket. Having never had an issue with oxidation, I can only assume the problem is much more theoretical than real. I have never used an autosiphon, so I’ve avoided that bullet.

How do you transfer denny?