Could someone explain, or point me to some info on cold side aeration and it’s effect on decreased shelf life, or staling reactions? I’m not 100%, but I suspect that there would be a difference if you take some cool wort, aerate it, then divide it into two containers. The 1st container is pitched immediately with the appropriate amount of yeast, the other container is pitched several days later, (3-7 days)
In the 1st container the yeast would scavenge all the O2 they need right away, while in the second container the 02 would be free to react with various wort compounds and decrease the shelf life and increase the staling of the finished beer. This is of course assuming that your sanitization practices are perfect. I’m not interested in hearing about problems related contamination issues.
Which compounds are responsible for staling/oxidization reactions?
Is my thinking correct?
[quote]I am not aware of any staling issues with aerating/oxygenation at pitching temps.
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I do not have a specific reference, but if this is true why are we so careful to avoid excess splashing when transferring beer? Some even advocate transferring under a CO2 blanket to avoid oxidization and staling.
I do not have a specific reference, but if this is true why are we so careful to avoid excess splashing when transferring beer? Some even advocate transferring under a CO2 blanket to avoid oxidization and staling.
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Are you talking about aerating during secondary transfers once the beer is done fermenting?
Yes, this is BAD NEWS
I think he’s asking whether letting aerated wort sit around before pitching for a significant time would have the same staling effect on the beer as introducing oxygen after the fermentation is complete and the chemistry behind what causes that. Logically you would think that it would but that’s just a guess on my part.
Ryan, welcome to the forum. This is a very interesting topic that you are starting with.
In the industry there seems to be a concern about wort aeration in general. While we all know about the hot side aeration (HAS) concern, I have also come across worries that aeration before pitching can accelerate staling reactions. The olive oil experiment was one of those things aimed at eliminating O2 addition to wort. I have also read about a brewing practice where the yeast is aerated before pitching but the wort itself is not aerated.
While these are all indications that there might be something to this, I don’t think we have much to worry here. Aerating the wort before pitching is still the most practical way for us to provide the yeast with the O2 it needs.
Ryan, you are proposing a very interesting experiment. It might be wort a try. I for example used to start the cold wort whirlpool by using the oxygen wand. The idea was to oxygenate and get the whirlpool going at the same time. After that I would rest the wort for up to an hour. I have abandoned this technique not because I noticed accelerated staling but because I didn’t considered it good practice anymore. Now I oxygenate in the fermenter after transfer and before pitching the yeast. The whirlpool is now started with my turkey baster that I use for sampling the wort.
My take is that there might be something to this but it is something you should not worry about unless you ran out of things to worry about. And even more important: it should not keep you from properly aerating your wort.
I am new to the forum, but am not a new brewer. This is more of a theoretical discussion than a practical one. I’m not at all worried about oxygenating before pitching, and agree that it is the easiest way to provide yeast some of the nutrients they need. This topic came up during a conversation with another brewer over the weekend. I suspect that aeration at any point in the process is bad for beer, but adding yeast soon after aeration protects it from the oxidation that would otherwise be detrimental.
I think the question to be answered would be: how long does aerated and unpitched wort need to stand to show an accelerated staling in a home brewing environment. Are we talking about hours or days?
Now that we seem to be over the HAS debate it’s time for a CSA debate :D.
I think we need to understand the oxidation process and/or mechanism. Oxidation should start immediately and continue until all available oxygen is consumed either by the yeast, converted to hydrogen peroxide, etc…
The known effects are browning, haze and cardboard like off-flavors but check out this study of packaged beer that indicates there is production of CL which can cause some of the effects we know so well.
I understand what he is asking now (duh). I was thinking in regard to pitching and not to transfer, so yes, I believe aerating and then letting the beer sit for days prior to pitching would be a bad thing in the long term since the oxygen introduced during the aeration could cause detrimental staling.
Now since someone mentioned HSA, how about a data point. Often we here people discuss HSA pre-boil. Well one day last year my spigot began to break on the tun and was drawing in air during the runoff. When I noticed the foam from the aeration was about half a converted keg in depth. My first thought was to stop it and then I thought it might be interesting to let it ride, boil, cool, ferment, etc. and determine just what staling effects had occurred. So the first keg drained pretty quickly without adverse effects. The second is STILL hanging out and has no indications of oxidation. It’s over a year old with diminishing charateristics due to age, but no oxidation. FWIW it is a Gotlandsdrika ~1.050. So, IMO, pre-boil HSA is not a concern - YMMV.
That’s good to hear. I had a similar problem in the brew I did this weekend. Not at that scale but at the end of the runoff I was blowing some air into the wort mainly due to the design on my MT. I was wondering if it would have any ill effects. Not that it’ll probably be around long enough to matter.