Here's a post from the celiac mailing list. Note casein is sometimes used
in winemaking. Don.

Newsgroup: bit.listserv.celiac
Date: Tue, 7 Oct 1997 11:36:17 -0700
From: Nancy Newlin <[log in to unmask]>
Subject: Re: wine - summary---Eggs used in winemaking

[snipped...] Here's a quote from an email I received from
Sue Ebeler, on the faculty of the Viticulture & Enology Department at
UC Davis (California) regarding my inquiry about eggs used in winemaking:

Yes eggs (the whites) are used in winemaking as a "fining" agent.  They are
not used in all wines.  It's very dependent on the winery, the winemaker,
etc.  Other protein agents that may also be used are casein, gelatin,
isinglass (a protein from fish bones) and some non-protein compounds such
as bentonite, and polysaccaride gums may also be used.

Most of the proteins (or other fining agents) are allowed to precipitate
out of solution and/or are filtered to remove them.  The actual amount of
residual protein that is left should be quite small, but I do not know if
it is enough to cause an allergic reaction.

[snipped....]