hist-brewing: keeping of beer

[John Isenhour]

Eliza hath typed:
 
 Does anyone know how long it takes for ale and beer to go off? I can't find
 any reference to this except from the common notion that the addition of
 hops and gruit improve the preservation.
 
It depends. Do you mean opened or unopened casks (assuming casks
from the period).  Old English ales that were aged were called
"stale", but some perferred that. Wooden aging vats harbor lactic acid
producing bacteria as well as brettanomyces, so "off" is relative.  

When serving cask ale's with beer going out the spigot and air going
in, rule of thumb is you have about 3 days, and the beer goes thru
perceptible changes during that time and is considered part of the
ritual.  Once air is introduced, acetobacter can grow causing vinegar
notes that are not acceptable unless you are talking about certain
belgian styles.

When I used to sell "real ale" if a lot was left at the end of the night
I would purge the headspace with CO2, and take it home.

OTOH, Thomas Hardy's in the bottle is supposed to get better for about
25 years, and in general the higher starting gravity beers tend to
keep if unopened.  Light gravity ale such as ordinary bitter should be
consumed just as it is finishing fermentation.

cheers,
john

217-328-0295                       Master Brewers Association of America
isenhour at uiuc.edu                   American Society of Brewing Chemists
University of Illinois/Urbana           Beer Judge Certification Program
Fermentation Science Instructor            Institute for Brewing Studies


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