hist-brewing: Brown malt equivalent?

[Christopher Swingley]

Greetings,

I've recently been trying my hand at brewing beers from historical 
recipes.  Dr. John Harrison's _Old British Beers_ has been a great 
resource for recipes, as well as for hints when trying to generate 
modern equivalents from old books.

One problem I've been having, however, is dealing with the low diastatic 
power of British pale malt since amber and brown malts (at least those 
made in my oven, according to Harrison) don't have many useful enzymes 
left.  Comments on rec.crafts.brewing regarding Maris Otter seem to 
indicate I can expect it to convert itself, plus maybe 20% more by 
weight of a non-enzymatic malt.

Harrison has a couple recipes in _Old British Beers_ that have higher 
than 5:1 pale:brown/amber malt ratios, but in most cases he states that 
you'll need powdered enzymes, or he provides a modern equivalent using 
crystal and other malts.

Has anyone found reference, or done experiments to determine what an 
appropriate, mashable replacement might be for brown (or amber) malt?  
Do you suppose this can be a simple as reducing the home-roasted malts 
to the requisite 20% of the grist, and then adding enough crystal to get 
the color (and presumably some of the roasted flavor too) up to the 
level you expect from the original recipe?

Any thoughts or experiences along these lines?

Thanks,

Chris
-- 
Christopher S. Swingley          email: cswingle at iarc.uaf.edu
IARC -- Frontier Program         Please use encryption.  GPG key at:
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