Under some conditions, the yeast will also consume some of the compounds in the
trub. The "fermentation" of these compounds can produce several off-flavors. In
addition, the dormant yeast on the bottom of the fermentor begin excreting more
amino and fatty acids. Leaving the post-primary beer on the trub and yeast cake
for too long (more than about three weeks) will tend to result in soapy flavors
becoming evident. Further, after very long times the yeast begin to die and break
down - autolysis, which produces yeasty or rubbery/fatty/meaty flavors and
aromas. For these reasons, it can be important to get the beer off of the trub and
dormant yeast during the conditioning phase.
There has been a lot of controversy within the homebrewing community on the
value of racking beers, particularly ales, to secondary fermentors. Many seasoned
homebrewers have declared that there is no real taste benefit and that the dangers
of contamination and the cost in additional time are not worth what little benefit
there may be. While I will agree that for a new brewer's first, low gravity, pale beer
that the risks probably outweigh the benefits; I have always argued that through
careful transfer, secondary fermentation is beneficial to nearly all beer styles. But
for now, I will advise new brewers to only use a single fermentor until they have
gained some experience with racking and sanitation.
Leaving an ale beer in the primary fermentor for a total of 2-3 weeks (instead of
just the one week most canned kits recommend), will provide time for the
conditioning reactions and improve the beer. This extra time will also let more
sediment settle out before bottling, resulting in a clearer beer and easier pouring.
And, three weeks in the primary fermentor is usually not enough time for off-
flavors to occur
8.3 Conditioning Processes
The conditioning process is a function of the yeast. The vigorous, primary stage is
over, the majority of the wort sugars have been converted to alcohol, and a lot of
the yeast are going dormant; but there is still yeast activity. During the earlier
phases, many different compounds were produced by the yeast in addition to
ethanol and CO2, e.g., acetaldehyde, esters, amino acids, ketones- diacetyl,
pentanedione, dimethyl sulfide, etc. Once the easy food is gone, the yeast start re-
processing these by-products. Diacetyl and pentanedione are two ketones that have
buttery and honey-like flavors. These compounds are considered flaws when
present in large amounts and can cause flavor stability problems during storage.
Acetaldehyde is an aldehyde that has a pronounced green apple smell and taste. It
is an intermediate compound in the production of ethanol. The yeast reduce these
compounds during the later stages of fermentation.
The yeast also produce an array of fusel alcohols during primary fermentation in
addition to ethanol. Fusels are higher molecular weight alcohols that often give
harsh solvent-like tastes to beer. During secondary fermentation, the yeast convert
these alcohols to more pleasant tasting fruity esters. Warmer temperatures
encourage ester production.
Towards the end of secondary fermentation, the suspended yeast flocculates
(settles out) and the beer clears. High molecular weight proteins also settle out
during this stage. Tannin/phenol compounds will bind with the proteins and also
settle out, greatly smoothing the taste of the beer. This process can be helped by
chilling the beer, very similar to the lagering process. In the case of ales, this
process is referred to as Cold Conditioning, and is a popular practice at most
brewpubs and microbreweries. Cold conditioning for a week clears the beer with or
without the use of finings. Fining agents, such as isinglass (fish bladders), Polyclar
(plastic dust), and gelatin, are added to the fermentor to help speed the
flocculation process and promote the settling of haze forming proteins and tannins.
While much of the emphasis on using finings is to combat aesthetic chill haze, the
real benefit of dropping those compounds is to improve the taste and stability of
8.4 Using Secondary Fermentors
Using a two stage fermentation requires a good understanding of the fermentation
process. At any time, racking the beer can adversely affect it because of potential
oxygen exposure and contamination risk. Racking the beer away from the
krausen/yeastbed before the Primary fermentation phase has completed can result
in a stuck (incomplete) fermentation and a final gravity that is too high.
It is important to minimize the amount of headspace in the secondary fermentor to
minimize the exposure to oxygen until the headspace can be purged by the still-
fermenting beer. For this reason, plastic buckets do not make good secondary
fermentors unless the beer is transferred just as the primary phase is starting to
slow and is still bubbling steadily. Five gallon glass carboys make the best
secondary fermentors. Plastic carboys do not work well because they are too
oxygen permeable, causing staling.
The following is a general procedure for using a secondary fermentor.
1. Allow the Primary Fermentation stage to wind down. This will be 2 - 6 days
(4 - 10 days for lagers) after pitching when the bubbling rate drops off
dramatically to about 1-5 per minute. The krausen will have started to settle
back into the beer.
Using a sanitized siphon (no sucking or splashing!), rack the beer off the
trub into a another clean fermentor and affix an airlock. The beer should still
be fairly cloudy with suspended yeast.
Racking from the primary may be done at any time after primary fermentation has
more-or-less completed. (Although if it has been more than 3 weeks, you may as
well bottle.) Most brewers will notice a brief increase in activity after racking, but
then all activity may cease. This is very normal, it is not additional primary
fermentation per se, but just dissolved carbon dioxide coming out of solution due to
the disturbance. Fermentation (conditioning) is still taking place, so just leave it
alone. A minimum useful time in the secondary fermentor is two weeks. Overly long
times in the secondary (for light ales- more than 6 weeks) may require the addition
of fresh yeast at bottling time for good carbonation. Always use the same strain as
the original. This situation is usually not a concern. See the next chapter and the
Recommended Reading Appendix for related information on lager brewing.
Different beer styles benefit from different lengths of conditioning. Generally, the
higher the Original Gravity, the longer the conditioning time to reach peak flavor.
Small beers like 1.035 Pale Ales will reach peak flavor within a couple weeks of
bottling. Stronger/more complex ales, like Stouts, may require a month or more.
Very strong beers like Doppelbocks and Barleywines will require 6 months to a year
before they condition to their peak flavor. (If oxidation doesn't take its toll first. I
have had some pretty awful year old barleywines.) This conditioning can be done in
either the secondary fermentor or the bottle, but the two methods do produce
different results. It is up to you to determine how long to give each phase to
produce your intended beer. When bottling your first few batches, its always a good
idea to set aside a six pack in the corner of the basement and leave it for a time. It
is enlightening to taste a homebrewed beer that has had two months to bottle
condition and compare it to what the batch initially tasted like.
8.5 Secondary Fermentor vs. Bottle Conditioning
Conditioning is a function of the yeast, therefore it is logical that the greater yeast
mass in the fermentor is more effective at conditioning than the smaller amount of
suspended yeast in the bottle. This is why I recommend that you give your beer
more time in the fermentor before bottling. When you add the priming sugar and
bottle your beer, the yeast go through the same three stages of fermentation as
the main batch, including the production of byproducts. If the beer is bottled early,
i.e. 1 week old, then that small amount of yeast in the bottle has to do the double
task of conditioning the priming byproducts as well as those from the main ferment.
You could very well end up with an off-flavored batch.
Do not be confused, I am not saying that bottle conditioning is bad, it is different.
Studies have shown that priming and bottle conditioning is a very unique form of
fermentation due to the oxygen present in the head space of the bottle. Additional
fermentables have been added to the beer to produce the carbonation, and this
results in very different ester profiles than those that are normally produced in the
main fermentor. In some styles, like Belgian Strong Ale, bottle conditioning and the
resultant flavors are the hallmark of the style. These styles cannot be produced
with the same flavors via kegging.
For the best results, the beer should be given time in a secondary fermentor before
priming and bottling. Even if the yeast have flocculated and the beer has cleared,
there are still active yeast in suspension that will ferment the priming sugar and
carbonate the beer
Hopefully this chapter has helped you understand what fermentation is and how it
works. You need to have sufficient yeast and the right conditions for them to work
under to achieve the best possible beer. The next chapter will use this information
to walk you through fermenting your first batch.
Miller, D., The Complete Handbook of Home Brewing, Storey Publishing, Pownal,
Fix, G., Principles of Brewing Science, Brewers Publications, Boulder Colorado,
Fix, G., Fix, L., An Analysis of Brewing Techniques
, Brewers Publications, Boulder
Briggs, D.E., Hough, J.S., Stevens, R., Young, T.W., Malting and Brewing Science,
Vol. 2, Aspen Publishers, Gaithersburg, Maryland, 1999.
Palmer, J., Conditioning - Fermentation's Grand Finale, Brewing Techniques
Wine Press, Vol. 5, No. 3, 1997
Alexander, S., personal communication, 1997.
Korzonas, A., personal communication, 1997
Chapter 9 - Fermenting Your First Beer
Choosing Your Fermenter
So now you have the fruit of your labors cooled in the boiling pot and you feel like
celebrating. But don't call in your friends because it's not beer yet. It won't be beer
until you have pitched your yeast, and the beer won't be finished until it has
completed fermenting which is probably a couple weeks away at least. And then
you will still need to bottle it... But have no fear, the hard part is over.
What we need to do now is transfer it to your fermenter, make sure the wort has
been aerated, pitch the yeast, and find a quiet place to put the fermenter for the
next couple weeks.
Buckets vs. Carboys
There are two types of fermenter commonly available: food grade plastic buckets
(bins) and glass carboys. Each type has its own merits. The plastic buckets are
slightly less expensive than the glass and much safer to handle. The buckets have
the outstanding option of being fitted with spigots, which makes siphoning
unnecessary; a real plus. The buckets are typically 6 gallons, giving 1 gallon of
headspace for the fermentation, which is usually sufficient.
The spigot option eliminates siphoning and is practically a necessity at bottling
time. A bottling bucket with a spigot allows greater control of the fill level. In my
opinion, this is the only way to bottle.
Although you will need a siphon, glass has the advantage of letting you see your
beer and be able to gauge the activity of the fermentation. There are two sizes
commonly available, a 6 1/2 gallon size that is perfect for primary fermentations
and a smaller 5 gallon size which is ideal for secondary fermentation. The large size
typically has enough headspace to contain the krausen, while the 5 gallon size
almost completely eliminates the headspace above the beer, preventing oxidation
during the conditioning phase. You will need to shield the carboys from the light,
but you can easily tell when fermentation is over and the yeast is settling out.
Airlocks vs. Blowoffs
The decision to use an airlock or blowoff hose is determined by headspace. Usually
the buckets and large carboys have enough headspace (at least 3 inches) that the
foam does not enter the airlock. If the fermentation is so vigorous that the foam
pops the airlock out of the lid, just rinse it out with sanitizer solution and wipe off
the lid before replacing it. Contamination is not a big problem during the primary
phase. With so much coming out of the fermenter, not much gets in. If the
fermentation keeps filling the airlock with crud and popping it out, there is an
The alternative is called a blowoff hose and it allows foam and hop remnants to be
carried out of the fermenter. A blowoff is a necessity if you are using a 5 gallon
carboy as your main fermenter. Get a 1 inch diameter plastic hose and fit this
snugly inside the mouth in the carboy or enlarge the hole in the bucket lid if
necessary. Run the hose down the side and submerge the end in a bucket of
sanitizer/water. It is important to use a large diameter hose to prevent clogging. If
the tube gets clogged, the fermenter can get pressurized and blow goo all over the
ceiling, or worse - burst.
9.1 Transferring the Wort
Your wort should be cool before you pour it into the fermenter. If it is not, refer to
Chapter 7 - Boiling and Cooling, for suggested cooling methods. But before you
transfer the wort to the fermenter, you may have been wondering what to do about
all the hops and gunk in the bottom of the pot.
There will be a considerable amount of hot break, cold break and hops in the
bottom of the boiling pot after cooling. It is a good idea to remove the hot break (or
the break in general) from the wort before fermenting. The hot break consists of
various proteins and fatty acids which can cause off-flavors, although a moderate
amount of hot break can go unnoticed in most beers. The cold break is not
considered to be much of a problem, in fact a small amount of cold break in the
fermenter is good because it can provide the yeast with needed nutrients. The hops
do not matter at all except that they take up room.
In general however, removal of most of the break, either by careful pouring from
the pot or by racking to another fermenter, is necessary to achieve the cleanest
tasting beer. If you are trying to make a very pale beer such as Pilsener style lager,
the removal of most of the hot and cold break can make a significant difference.
The most common method for separating the wort from the break is to carefully
decant the wort off of it into the fermenter, leaving the break behind. Pouring the
wort through a stainless steel strainer can also help with this approach. If you are
siphoning the cooled wort from the pot, then a copper scrubby pad and whirlpooling
can help. Whirlpooling is a means of gathering most of the break and hops into the
center of the pot to better enable the siphon to draw off clear wort from the side.
Rapidly stir the wort in a circular manner. Continue stirring until all the liquid is
moving and a whirlpool forms. Stop stirring and let the whirlpool slow down and
settle for 10 minutes or so. The whirlpooling action will form a pile in the center of
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