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