[majorvices]

I will just have to disagree with Saccharomyces - I ran a craft brewery that didn't have a filter and experienced problems with oxidation (we do have a cetrifuge but that was added only 3 years ago). I have experienced oxidation as a homebrewer as well. Purging all vessels with co2 mitigated or eliminated the problems. I know many others in the industry that do not filter and go to lengths to eliminate oxidation. I have access to a DO meter I will see if I can do some tests later next year on how much o2 remains in an unpurged secondary after racking.

[tommymorris]

I will just have to disagree with Saccharomyces - I ran a craft brewery that didn't have a filter and experienced problems with oxidation (we do have a cetrifuge but that was added only 3 years ago). I have experienced oxidation as a homebrewer as well. Purging all vessels with co2 mitigated or eliminated the problems. I know many others in the industry that do not filter and go to lengths to eliminate oxidation. I have access to a DO meter I will see if I can do some tests later next year on how much o2 remains in an unpurged secondary after racking.

I feel like I want to agree with both of you. I purge the keg with CO2 and am careful when transferring but I don’t achieve closed transfers. I crack the fermenter lid and use gravity to fill a purged keg. I fill into the out post using a ported fermenter to liquid QD into the keg. The keg lid is sealed during transfer and I purge the tubing in addition to the keg before starting. Maybe I can’t taste oxidation but I don’t  think my beer is stale or oxidized. Even my light lagers are crisp and clean. My kegs go right into the fridge and I drink them within 6-8 weeks. They are never warm.

So maybe my process is good enough.

But, I have also done some awful things to beer. At least twice over the years I have had bad transfers (stuck) and just given up and poured the beer from the fermenter into the keg. I remember the last time I did this I thought after. Wow! That was great beer. I couldn’t believe it wasn’t oxidized.  I am sure I got lucky. I was just gonna toss the beer if it was ruined. It wasn’t.

[majorvices]

Homebrewers have a lot of control over their beer and keeping beer cold will slow down the effects of oxidation greatly. I'm with you that I have had screw up where I thought the beer was going to be ruined and it turned out just fine.

[ynotbrusum]

Of course there is the spunding approach to avoiding oxidation in the keg/secondary...

But I have to say, back when I used a secondary and racked after the primary fermentation was complete, I could see oxidation from a slight darkening.  Maybe that put confirmation bias in my head, but I recall an Altbier I made that was cardboard in less than a month in the secondary.  So, probably insufficient yeast were in suspension on that one.

Good discussion fellows!

[majorvices]

Of course there is the spunding approach to avoiding oxidation in the keg/secondary...

But I have to say, back when I used a secondary and racked after the primary fermentation was complete, I could see oxidation from a slight darkening.  Maybe that put confirmation bias in my head, but I recall an Altbier I made that was cardboard in less than a month in the secondary.  So, probably insufficient yeast were in suspension on that one.

Good discussion fellows!

I used to bottle condition a lot. The bottles I purged with co2 first lasted a lot longer than the ones simply primed.

[Saccharomyces]

Oxidation is one of the most poorly understood aspects of brewing at the amateur and small to mid-size professional brewing level. Cardboard and Sherry-like flavors are the result of a problem upstream from fermentation (i.e., during malting and/or mashing). No amount of O₂ purging on the cold side will fix these off flavors. Given enough time, these flavors will show up. Beer that contains a live culture that is heavily oxidized during cold side transfers does not result in cardboard. It results in cidery and cider vinegar-like flavors due to the reduction of ethanol to acetaldehyde and then to acetate. In the presence of O₂ and no available carbon sources that can be reduced to a directly consumable hexose (i.e., sugars with the formula C₆H₁₂O₆), Crabtree positive yeast cells enter diauxic shift where they switch to using ethanol respiratively as their carbon source. 

https://pathway.yeastgenome.org/YEAST/NEW-IMAGE?type=PATHWAY&object=PWY3O-4300

“S. cerevisiae, as a Crabtree-positive yeast, predominantly ferments pyruvate to ethanol in high glucose conditions. When glucose or other preferred carbon sources are depleted, S. cerevisiae switches to aerobic respiration and utilizes ethanol as carbon source instead, a phenomenon known as diauxic shift. Ethanol degradation is a three-step pathway that begins with the oxidation of ethanol to acetaldehyde by alcohol dehydrogenase (ADH). Aldehyde dehydrogenase (ALD) then converts acetaldehyde to acetate, which acetyl-CoA synthetase (ACS) subsequently ligates with coenzyme A to produce acetyl-CoA.

Alcohol and aldehyde dehydrogenase each have several isozymes in S. cerevisiae. Of the alcohol dehydrogenases involved in catalyzing interconversion between ethanol and acetaldehyde, the cytosolic enzyme Adh2p is thought to preferentially catalyze ethanol oxidation to acetaldehyde due to its relatively low Km for ethanol. ADH2 is glucose-repressed and activated by Cat8p and Adr1p. The oxidation of acetaldehyde to acetate is catalyzed by both cytosolic and mitochondrial aldehyde dehydrogenase, of which the main isoforms (Ald6p and Ald4p, respectively) are important for growth on ethanol.”

[majorvices]

Between the LoDo guys telling us our beer sucks if we don't brew under a vacuum and Saccharomyces saying that aeration post fermentation is not a concern I'm not sure which way to turn... if only there was a middle ground!

[ravenwater]

Between the LoDo guys telling us our beer sucks if we don't brew under a vacuum and Saccharomyces saying that aeration post fermentation is not a concern I'm not sure which way to turn... if only there was a middle ground!

There are no doubt many who are much more expert than me, and it can feel hard sometimes to sort out what the facts are as well as what may be more important than something else in terms of being happy with the outcomes of my brewing. At any rate, to return to the OP, as far as use of a secondary goes, even if it is not saving me from the terrors of oxygen exposure upon transfer to a secondary I have no reason for such a transfer in all but a few cases, so why would I bother? Simpler is better where nothing is lost. I can let a beer sit in the primary (only) fermentation vessel for weeks and be happy with the beer I produce.

[denny]

Between the LoDo guys telling us our beer sucks if we don't brew under a vacuum and Saccharomyces saying that aeration post fermentation is not a concern I'm not sure which way to turn... if only there was a middle ground!

There is....your own experience and goals in homebrewing.  Do what works for you and don't worry about it.

[ASLO]

One more reason (in addition to oxidation and contamination concerns) not to transfer to a secondary is that it requires you to clean and sanitize additional equipment. In my experience, my beers don't gain any benefits from transferring to a secondary that the same time spent in primary can't also provide. Certainly there may be circumstances when transferring makes sense, for instance if you want to bulk-age a beer and would like to free up your fermentor or re-pitch the yeast, but for most beers, I think a month (or two) in primary is the way to go.

[hopfenundmalz]

Between the LoDo guys telling us our beer sucks if we don't brew under a vacuum and Saccharomyces saying that aeration post fermentation is not a concern I'm not sure which way to turn... if only there was a middle ground!

It depends on on the beer, no?

I have had many sublime beers from British brewers using Victorian technology breweries and cask conditioned ales exposed to O2.

I've had highly technical beers from the likes of Schönem, Augustiner, and Ayinger that are great for their styles. There are many small German breweries that make fine beer with less technical attention. Every now and then you can taste one and go this has Herbstoffe, but halfway through the beer you say it is now in the bachground drink up.

[mdyer909]

Interesting discussion.  If I’m going to lager a beer (I’m a bottler) I usually rack off the yeast into a carboy and top it up with distilled water if necessary.  I’m doing my first Scottish style now and reading a lot of recommendations about cold storing for 3 weeks or so after fermentation.  I’m fermenting at around 60F and using Omega Irish ale yeast in a PET vessel.  Think I can safely just drop in down to the high 30s for a couple of weeks in the fermenter with little worry?

[majorvices]

Between the LoDo guys telling us our beer sucks if we don't brew under a vacuum and Saccharomyces saying that aeration post fermentation is not a concern I'm not sure which way to turn... if only there was a middle ground!

It depends on on the beer, no?

I have had many sublime beers from British brewers using Victorian technology breweries and cask conditioned ales exposed to O2.

I've had highly technical beers from the likes of Schönem, Augustiner, and Ayinger that are great for their styles. There are many small German breweries that make fine beer with less technical attention. Every now and then you can taste one and go this has Herbstoffe, but halfway through the beer you say it is now in the bachground drink up.

Absolutely agree. However, I will forever preach for homebrewers to limit exposure to o2 post fermentation as much as possible for best results.

[hopfenundmalz]

Between the LoDo guys telling us our beer sucks if we don't brew under a vacuum and Saccharomyces saying that aeration post fermentation is not a concern I'm not sure which way to turn... if only there was a middle ground!

It depends on on the beer, no?

I have had many sublime beers from British brewers using Victorian technology breweries and cask conditioned ales exposed to O2.

I've had highly technical beers from the likes of Schönem, Augustiner, and Ayinger that are great for their styles. There are many small German breweries that make fine beer with less technical attention. Every now and then you can taste one and go this has Herbstoffe, but halfway through the beer you say it is now in the bachground drink up.

Absolutely agree. However, I will forever preach for homebrewers to limit exposure to o2 post fermentation as much as possible for best results.

Same here Kieth.

Cask ales in England get some great flavor in the Cask when vented the n fall off quickly after 2-3 days.

[goose]

There is....your own experience and goals in homebrewing.  Do what works for you and don't worry about it.

^^^^  This.

I live by the mantra in homebrewing, if it ain't broke, don't fix it.