Let's assume I've read all I can about the pros and cons of racking my beer from primary to secondary and I've decided that I want my lager clear and I'm going to rack away. I've brewed a dozen batches and have learned how to keep things sanitized, how to carefully use my auto-siphon, how to properly transfer to my bottling bucket, etc. I'm careful and deliberate. I'm doing my best to keep the beer from splashing and bubbling as I transfer. I've created some fruity beers due to high fermentation temps, but have zero infected beers. So if I'm careful about my process of racking to a secondary fermenter, how does my beer become oxidized? I'm asking because that seems to be a primary reason for NOT racking to secondary, yet I'm unable to figure out exactly how this will happen, assuming I am thoughtful and careful about the transfer. I would like to hear someone describe the way that oxidation happens under careful, deliberate circumstances when a home brewer is aware of the debate and aware of what one should or should not do during the transfer. Because I'm wondering if the whole "oxidation" concern is really only applicable to someone who is splish-splashing around in the kitchen.

4 Answers 4


By being safe and deliberate with your racking methods, I doubt you'll have much of a problem. I believe a fair amount of the problems stem from lack of improper methods of racking (among other things). Some of the things that cause oxidation include:

  • Not getting the siphon tube to sit in the bottom of carboy/bucket/keg while transferring
  • Getting a lot of bubbles pushed through the siphon
  • A warped auto-siphon (melting with the transfer of hot liquid)
  • shaking carboys during fermentation if oxygen is present in the container (e.g. brewer uncorks the carboy, does whatever, corks it again, then shakes it)
  • Quickly force carbonating kegs
  • Several other lesser destructive methods

I've never had oxidation issues, and have almost always racked to a second vessel for clarity/aging. I'm welcome to other's input and even telling me I'm incorrect, but to me, I feel as though the recent oxidation concerns are a bit over-hyped. As long as you are conscious in your efforts, I doubt you'll notice any off flavors. I would imagine a lot of the bad-rep racking gets is due to people carelessly transferring their beer between vessels enough, to the point where people figure the only hope they have for correction is to just not transfer the beer, which is as paranoid as it is silly. Getting your beer off the yeast cake and into a secondary vessel has vast benefits for maturation. For someone to say "Just leave it in primary because you probably aren't capable of racking correctly" doesn't sit well with me.

Unless someone has a compelling argument otherwise (I'm reasonable enough to hear it out), I'd recommend with what you want, that you not only should, but need to rack your beer into a secondary vessel. Make sure you take all the steps to prevent oxidation, and if you still encounter oxidation off flavors, I'd be shocked.


Oxidization happens when there is oxygen dissolved in the beer, such when the beer is splashed or agitated in air.

I've always been careful with racking, using either a regular siphon started by blowing into the carboy (through a sanitary air filter) or via an autosiphon. About 2 years ago, I had oxidization problems in a few batches which appeared after racking to the keg. I fixed by using CO2 to push the beer, and I also bought a new siphon for cases when I can't use CO2 pressure.

Some ways to avoid oxidization are:

  • avoid splashing or agitating the beer - this helps keep the oxygen out of the beer in the first place
  • purge all air with CO2 before racking - then splashing the beer won't do any harm
  • add an anti-oxidant to the beer, e.g. 1/8 tsp of ascorbic acid to 5 gallons - this will help reduce the amount of free oxygen in the beer, and thus reduce staling due to oxidization.
  • use priming sugar rather than force carbonating - the yeast will scavenge some of the oxygen
  • if bottling, use oxygen-scavenging bottle caps.

As to deliberately oxidizing the beer, you would simply need to arrange for the beer to be agitated during transfer.

Temperature is also a key component - oxidization happens 3-fold quicker for each 10°C/18°F increase in temperature. So if you wanted to deliberately oxidize a beer quickly, say to see how it tastes, simply keep it warm (70°C/160°F) for a few hours, then chill and taste side by side a beer that hasn't been kept warm.


"Because I'm wondering if the whole "oxidation" concern is really only applicable to someone who is splish-splashing around in the kitchen." In a word, yes.

  • 1
    I taste oxidized beers all of the time at the various homebrew clubs I attend. Those brewers know what not to do, but they still end up with stale beer, so I'd say you can be careful, and still get oxidation.
    – Dale
    Commented Jul 29, 2013 at 0:29
  • 1
    OTOH, I'm careful and I can't recall one of my 442 batches that was oxidized under normal conditions (meaning no extended aging). So it seems like the guys you're talking about may not be as careful as they think they are.
    – Denny Conn
    Commented Jul 29, 2013 at 1:27

I watched a brewer vigorously churn his near boiling hot wort (insert and raise the wort chiller (copper coil) repeated times to crash the temperature from the boil down to near pitching temperatures... think churning butter image, that is what he was doing. Also watched as he transferred from primary to secondary with the hose a foot off the bottom of the vessel being transferred into. I expect the same happens when he transfers into the serving keg. Then his practice (like many of us) is to force carbonate his kegs with 40 psi and shaking the hell out of the keg. My guess is that he never purges the air out of the keg with C02 before the shaking of the keg.

All of these errors in practice will oxidize your beer. He asked me why all his beers seem to have a distinctively similar taste...oxidation. Just those sloppy practices is all it takes to ruin a likely good batch of beer.

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