H2O - Good and Bad / Brewing Tips
Home Brewing Recipes
Baker Street Ales Associate Brewer
Arny Lands
Beer Nexus
the crossroads of the beer world
Wow, last month's column generated a lot of e-mails.  I try to answer
each one personally so please be patient if I haven't gotten to yours
yet.  I thought I'd focus in on a general topic today instead of just giving
you some recipes.   I'd lie to tell you about oxygen in your home brew.   
Of course Commercial brewers go to extreme lengths to reduce the
amount of oxygen in their finished beers, and as a home brewer you
should be concerned about oxygen as well. Oxygen can spoil the long
term stability of your beer flavor and clarity and lead to a variety of off
flavors.

Before fermentation, oxygen is generally a good thing. In fact oxygen is
needed to allow healthy yeast growth during fermentation, which is why
many brewers aerate their beer before they pitch the yeast. Unless you
use pure oxygen it is difficult to over-oxygenate your wort before
fermentation. In early stages of yeast growth, the yeast will actually
scrub all of the oxygen from the beer and use it to grow and expand.

After the yeast has started fermentation, however, oxygen is considered
a contaminant. Many of us who rented party kegs or beer balls with a
hand pump on them in our college days saw first-hand how oxygen
spoils beer. These keg hand pumps put oxygen directly in the keg which
meant that the beer would spoil within a very short period, often giving it
a stale flavor within 24 hours. So the kegs needed to be consumed
rapidly to compensate though I have to admit that was never a serious
worry in my parties (at least in college).  So, oxygen, even in very small
quantities is bad for finished beer. Not only does it rapidly spoil your
beer, it can also damage the long term flavor stability of your beer even
in small quantities.

Clarity also suffers in beer with free oxygen as the oxygen will interact
with polyphenols and tannins in the beer to create chill haze and
eventually a permanent haze in the beer. Once fermentation is
complete, a layer of carbon dioxide, which is heavier than air, sits above
the beer and provides a protective layer in your fermenter. If you don’t
disturb the beer, that layer does a good job of protecting your beer as it
ages.

For home brewers, oxygen is most often introduced when transferring
beer from one vessel to another and also during the bottling or kegging
process. Excessive splashing during transfer, small leaks in your siphon
or kegging system or a poor seal on your bottle caps or keg can lead to
excessive oxygen.

One strategy is simply to avoid transferring your beer as much as
possible. Many brewers now skip the secondary fermentation entirely
and bottle directly from their primary fermenter. Commercial brewers
make use of conical fermenters, which let them remove excess yeast
and sediment without transferring their beer.

Splashing during transfer and bottling is a large source of oxygen. Auto-
siphon devices with a poor seal also often will pull oxygen in through the
seal when siphoning. This can be seen as bubbles near the seal when
siphoning. If you have a leaky auto siphon you should discard it or add
sterile water above the seal so it pulls water and not air if needed.

For bottling, you should try to keep your headspace to a minimum
(generally an inch or so is sufficient), avoid splashing your beer when
filling and use oxygen absorbing bottle caps if you have access to them.
Also be sure to carefully adjust and check your bottle capper on some
bottles as even a small leak will leave your beer undercarbonated and  
stale.

                                      ===========

And now to answer a questions sent in by several extract home brewers -

Yes,fresh extract alone can brew fantastic beer as long as your recipe
formulation and brewing technique are good. One of the best beers I've
ever brewed was made with extract!  
Here are five tips for extract brewers -
1.  Be sure to fully boil the wort.
2.  Use only fresh extract.  Don't settle for outdated stuff.
3.  Do not scorch your extract.  Pay close attention to it.
4.  Yeast - It's very important to pitch healthy yeast in adequate                
numbers, and use yeast that's appropriate for the style.
5.  Never ever rush your beer. At least 2-3 weeks in primary before
either bottling or moving to secondary, and if you're bottle conditioning
give your beers at least 6-8 weeks in the bottle.

Hope you found something of interest in the month's column.  I'll do my
best to keep writing something you'll find interesting.  And as always,
please keep sending me questions and comments.  Thanks.


                 That's it for this month.  Hope to see you next time!


          Good Brewing and Cheers!

             Arny Lands
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