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This question mentions a debate about secondary fermentation. Sort of like the existence of dark matter, everything I have read about homebrewing points to there being some disagreement about secondary fermentation. However, it would be handy to me to know what both sides of the debate actually are.

Can someone sketch them for me?

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This question may be helpful: homebrew.stackexchange.com/questions/5079/… –  Dustin Rasener Jun 27 '12 at 22:57

6 Answers 6

up vote 15 down vote accepted

I'll simply quote part of what John Palmer said in the "Ask the Experts" section if the American Homebrewers Association website....

"The risk inherent to any beer transfer, whether it is fermenter-to-fermenter or fermenter-to-bottles, is oxidation and staling. Any oxygen exposure after fermentation will lead to staling, and the more exposure, and the warmer the storage temperature, the faster the beer will go stale.

Racking to a secondary fermenter used to be recommended because staling was simply a fact of life – like death and taxes. But the risk of autolysis was real and worth avoiding – like cholera. In other words, you know you are going to die eventually, but death by cholera is worth avoiding.

But then modern medicine appeared, or in our case, better yeast and better yeast-handling information. Suddenly, death by autolysis is rare for a beer because of two factors: the freshness and health of the yeast being pitched has drastically improved, and proper pitching rates are better understood. The yeast no longer drop dead and burst like Mr. Creosote from Monty Python’s The Meaning of Life when fermentation is complete – they are able to hibernate and wait for the next fermentation to come around. The beer has time to clarify in the primary fermenter without generating off-flavors. With autolysis no longer a concern, staling becomes the main problem. The shelf life of a beer can be greatly enhanced by avoiding oxygen exposure and storing the beer cold (after it has had time to carbonate).

Therefore I, and Jamil and White Labs and Wyeast Labs, do not recommend racking to a secondary fermenter for ANY ale, except when conducting an actual second fermentation, such as adding fruit or souring. Racking to prevent autolysis is not necessary, and therefore the risk of oxidation is completely avoidable. Even lagers do not require racking to a second fermenter before lagering. With the right pitching rate, using fresh healthy yeast, and proper aeration of the wort prior to pitching, the fermentation of the beer will be complete within 3-8 days (bigger = longer). This time period includes the secondary or conditioning phase of fermentation when the yeast clean up acetaldehyde and diacetyl. The real purpose of lagering a beer is to use the colder temperatures to encourage the yeast to flocculate and promote the precipitation and sedimentation of microparticles and haze.

So, the new rule of thumb: don’t rack a beer to a secondary, ever, unless you are going to conduct a secondary fermentation."

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1  
Correct me if I don't understand your answer, but I think you're asking a question which wasn't asked. The question is "What is the secondary fermentation debate?" –  MStodd Jun 28 '12 at 18:19
1  
Although I did upvote, I think you're right, this mostly looks at one side of the argument rather than the entire debate. –  mdma Jun 28 '12 at 19:05
    
Classic example of a long winded Palmer answer, that doesn't actually answer what someone is asking!!! It is only one side of the debate; but Palmer is gospel so I'll put it down as THE answer to the question. Sorry Denny. –  brewchez Jul 1 '12 at 19:38

The debate is basically whether there is any benefit to the risk(s) caused by racking to a secondary fermenter after the primary fermentation has completed.

There are many reasons people rack to a secondary fermenter. This isn't the place to discuss whether they're myths or not, but here are the reasons:

  • Getting the beer off the trub helps it clarify
  • Delicate flavor ingredients that can't be added to the primary during fermentation can now be added
  • Getting the beer off the trub helps prevent off flavors the yeast will start imparting

Sources: What's the point of secondary fermentation?

With any passion, there are people who over complicate things to the point of failure, and that's where the real debate comes in. Do these steps over complicate the process and simply introduce another source of risk, or is there some benefit here for certain circumstances?

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I don't claim to know all the facets of all the arguments, but here's what I've garnered from what I've read.

Argument for racking to secondary: Allowing the beer to sit on the yeast cake will produce off flavors.

Argument Against: Racking can lead to oxidation and letting the beer sit on the yeast isn't really going to do much.

The "argument against" was made after the "argument for".

The caveat is if you're racking onto fruit or some other situation that necessitates actually moving the beer.

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The argument only really exists among beer homebrewers, actually. Racking to secondary (and tertiary, and quaternary...) is accepted and necessary in winemaking.

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But not in commercial brewing. –  Denny Conn Jun 27 '12 at 19:50
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In commercial brewing the fermentation tank is lightly pressurized with CO2 and the valve at the bottom of the fermenter is opened until the yeast is drained. So in effect, commercial brewers (at least the one I hang around at) DO remove yeast. They also transfer from fermenters to bright tanks. So I would say commercial (at least on the craft level) take steps to separate beer from yeast before packaging. –  Dale Jun 27 '12 at 21:42
    
Just what I was getting at. They do drop the yeast, but they don't xfer to a separate vessel to do that. –  Denny Conn Jun 28 '12 at 16:48
    
If dropping the yeast is necessary, how does a homebrewer drop the yeast when fermenting in a bucket or carboy? –  mdma Jun 28 '12 at 19:08
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Its only necessary in a big conical because the increased fluid pressure on the yeast bed promotes autolysis far more than with a small flat-bottomed bucket –  bk0 Jun 29 '12 at 2:27

I can offer only my personal experience from almost 10 years ago when me and my friends first started brewing when we were 16. We added glucose to the beer before sealing the bottles to create a sort of second fermentation. We only did this because we had some really poor materials and equipment to start with and it made the beer taste genuinely better, have more CO2 and feel less like the cheapest possible brew that it was. But we stopped doing this later because it was simply unnecessary - higher quality beer tasted better without it.

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                            Use Secondary Fermentation         Do Not Use Secondary 
                                                               Fermentation
--------------------      ---------------------              ----------------------------

Oxydation Risk            Increased risk of oxydation.       No increased risk of 
                          This occurs whenever beer is       oxydation.
                          transferred.  It can be 
                          minimized, and the effect on 
                          the final product may be small 
                          or noticable.



Contamination Risk        Increased risk of                  No increased risk of 
                          contamination through contact      contamination.
                          with additional equipement and 
                          air.




Brewing Workload          Increased workload to execute      No increase in brewing 
                          the transfer and prepare/clean     workload.
                          another vessel.





Additional Equipment      Increased expenditure on           Reduced expediture required on 
                          fermentation vessels is            fermentation vessels.
                          required.  This is a bad thing 
                          if you have to buy it, but a 
                          good thing if you are selling 
                          equipment.  If I sold 
                          fermenters, I would leave the 
                          transfer to secondary step in 
                          my version of the recipe.




Computed Efficiency       Slight reduction in brewhouse      No additional reduction in 
                          efficiency due to the losses       brewhouse efficiency.
                          associated with the additional 
                          transfer.





Autolysis Risk            Reduced risk of old yeast          Increased risk of old yeast 
                          imparting unwanted flavors         imparting unwanted flavors. 
                          from autolysis.                    According to Palmer "death by 
                                                              autolysis is rare for a beer 
                                                              because of two factors: the 
                                                              freshness and health of the 
                                                              yeast being pitched has 
                                                              drastically improved, and 
                                                              proper pitching rates are 
                                                              better understood."  He 
                                                              continues "...they are able to 
                                                              hibernate and wait for the 
                                                              next fermentation to come 
                                                              around. The beer has time to 
                                                              clarify in the primary 


Clarity of the Beer       Increased clarity may be           The highest clarity may not be 
                          attained.  Less care is            attained.  Although with 
                          required at packaging time to      appropriate handling, 
                          assure yeast and sediment are      packaging from primary can 
                          not packaged.                      produce highly clear beers.  
                                                             In general though, more care 
                                                             is required at packaging time 
                                                             to assure yeast and sediment 
                                                             are not packaged.


Ability to Add            Allows for the brewer to rack      Process to add fruit or other 
Delicate Flavor           onto fruit.  Allows for the        flavor ingredients to the 
Ingredients or Fruit      brewer to add flavor               primary may be problematic.
                          ingredients that would 
                          otherwise be inhibited by 
                          having a thick layer of yeast 
                          / sediment.
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The best form of flattery... –  Dale Jul 1 '12 at 14:52
    
I like it, but there must be a better way to format it. –  Kortuk Jul 1 '12 at 15:07
    
if anyone wants to format it to yield a more pleasant look, please feel free, or advise me how to do it. –  Dale Jul 2 '12 at 16:39
    
I would have if I had known a way of doing so. –  Kortuk Jul 2 '12 at 20:08

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