Hey everyone, I have a question about secondary fermentation. So, from what I’ve read there really shouldn’t be any airlock activity when you but a beer into secondary. However, I also have read that a beer shouldn’t come into contact with oxygen or the flavor will go off and that during fermentation this is prevented because CO2, a byproduct of fermentation, is heavier than normal air and so it forms a protective barrier over the beer as well as forcing out the normal air through the fermentation lock. So, my question is, when we transfer the beer to the secondary, we lose the protective layer of C02 and it doesn’t get replenished since the yeast is no longer producing it so, how do you prevent the beer in the secondary from oxidizing? Should I add a little bit of corn sugar to perk up the yeast and make a little CO2, or does it matter?
If you keg then you can purge the carboy with co2, also it’s best to have the secondary full to the top to reduce the amount of surface area. Some co2 will come out of solution when you transfer which will help. Most people don’t do secondary’s any more unless your adding fruit, dry hopping bulk aging then there is really no need.
bnheise-Back when 1st starting out, I had the same thought as you and would add something fermentable to secondary to reform a CO2 layer- a little sugar, some honey maybe. But, as gdtech said, some CO2 will come out of solution when transferring, so it’s really not an issue. Most important to prevent oxidation is gentle siphoning during transfer, and limiting the head space. By the way, the only time that I use cold conditioning now is when lagering and those pseudo-lagers like altbiers where I lager for 3-4 weeks. Dryhopping, adding fruit, cold crashing and gelatin - I do all that in primary. Except for winter lagering season, my carboys get lonely.
Even if your beer has reached final gravity it will still “gas off” for a while. So unless you left it in the primary for a long time, I would not worry.
With most beers you certainly can get away with no secondary. They are good for a few reasons. First you might want that primary fermentor back to do another batch. To dry hop or add fruit as already said. To help clear your beer. Some big beers that you want to age or let ferment for a long time will be better if you transfer off the dead yeast and into a secondary.
When I first started the rule of thumb was everything went into a secondary. We now know that is not always necessary. Some kits still advise it though. It sure won’t hurt any as long as everything is sanitary.
