hist-brewing: Re: hist-brewing digest, Vol 1 #9 - 2 msgs
brewinfo at xnet.com
Mon Nov 26 18:03:13 PST 2001
From: Bob Davis <brewer at enter.net>
> On the
> subject of racking, I have a couple of questions:
> >Racking multiple times will alleviate this. Take a page from the wine
> >and mead-maker's playbook and simply rack four or five times. I use a
> >pyramid scheme --
> >Primary -- max 7 days
> >Secondary -- max two weeks
> >Tertiary -- max three weeks
> >Quaternary -- max four weeks
> 1. Doesn't this much racking risk oxygenating the beer?
How long a beer can stay in the primary is proportional to the OG
and the intensity of flavour. I've had ribbon-winning barleywines
that spent six months in the primary... yes *primary*. It's mostly
due to my being busy, but I agree that minimizing racking will also
minimize oxidation. I rack as little as possible. I don't agree
that racking more than once will improve the beer significantly.
>Not if you're careful. There will be some oxygen pickup, but it will be
>minimal so long as you avoid splashing. And that which *is* picked up
>will mostly be eliminated during the bottle/keg conditioning phase.
A very small amount of any oxygen that is picked up late in the ferment
will be consumed by the yeast. There are a great many compounds in
beer yearn for oxygen and their oxidation products are not pleasant.
One group that comes immediately to mind is alcohols. Oxidised
alcohols are aldehydes and they are unpleasant. If fermentation is
still active, oxygen introduced will react with the alpha acetolactic
acid and produce diacetyl. Too much diacetyl and the yeast won't be
able to absorb all of it during conditioning/lagering.
I rack my ales only at bottling time and usually don't rack my lagers
until bottling time either. I think that all the fears of autolysis
come from the old days when you had a choice of two or three poorly
made dry yeasts. Now, we have nearly pure culture dry and liquid
yeasts that (in my experience) simply won't autolyse for at least
six months presuming that you have fed them enough oxygen at pitching
time and have pitched a large enough amount of yeast.
My *guess* is to the amount of racking done in historical beers
ranges from "none" to "a lot." There are some yeasts that settle
so quickly that they require rousing to finish the job. The Old
Brewery at Tadcaster uses one of those yeast strains to make Samuel
Smith's beers and they have pumps that rouse the yeast (introducing
lots of oxygen... subsequently, these beers have some of the
highest diacetyl and aldehyde levels of any commercial beers).
Burton Bridge uses a yeast like this too. There are a whole chain
of breweries in the US that use a yeast like this, but their name
escapes me. There's one in the Tampa airport. If the yeast doesn't
have this problem, my guess would be that virtually no racking is
done. Recall that even as late as the mid 1800's clarity was not
a big issue with beer. Czech brewers made a big deal out of clarity
mostly because a lot of nice glassware came from that area.
Al Korzonas, Homer Glen, Illinois, USA
korz at brewinfo.org
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