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Listmates:

This is a post that I recalled and finally located in the archives.
I think it covers the basics and what a chemist did to show us how
distillation works.  I have posted the additional information
contained in the original post.  Some of the information overlaps
information in Part II.

Betsy
Austin, Texas

 From a post by Janet Rinehart 11/16/01
http://maelstrom.stjohns.edu/CGI/wa.exe?A2=ind0111C&L=celiac&P=R1171&m=16544

A Ph.D. chemist did a distillation experiment at our Sept. Houston
chapter meeting.  Here is the summary.  Note the paragraph at the end
commenting on a new development at the CSA Annual Conference.  This
is exerpted from the November 2001 issue of the Houston chapter
Newsletter.

DISTILLATION EXPERIMENT - Presented by John Longo, Ph.D.

The distillation process, whether it's for alcohol or vinegar, is of
interest to John, a recently diagnosed celiac and a chemist.  He
wanted to have some independent information on the controversy that
one sees on the Internet or in a variety of articles about gluten in
vinegar.  To
demonstrate that gluten/gliadin is not transferred to the product
during distillation, John used some white vinegar to which he added
Eriochrome Black T (EBT), a common coloring agent used by chemists to
do titrations. The vinegar had about 300 ppm (parts per million) or
0.03% of the coloring agent which made the vinegar a dark purple.
The Europeans and Canadians use 200 ppm as a cutoff for
gluten/gliadin.
That level, 200 ppm of gluten, is considered okay to digest.  To put
that into perspective, that's 200 mg. in a whole liter of water.

Distillation involves boiling a liquid to a high enough temperature
to make steam-like vapors. The original solution of 300 ppm EBT in
vinegar was boiling vigorously.  What's coming over is whatever is
carried over by the distillation process. Only the vapors come up and
are cooled by the air, condense back to a liquid and flow into the
receiving cup. (In a more efficient distillation process, the vapors
are water-cooled.)  He showed a jar with just 1 ppm of EBT in the
vinegar solution, which was light pink, but the color was still
evident.  For comparison, He had a separate jar showing the rather
dark color of fluid with 200 ppm EBT.
He then showed a jar with just plain water - totally clear.  The
distilled liquid coming through the tubing was also totally clear and
had NO COLOR at all indicating that less than 1 ppm of EBT was
carried over during distillation.  We could smell the vinegar in the
front of the room.  This was just normal 6% acetic acid.  Acetic acid
has a molecular weight of 60.  That's actually heavier than ethyl
alcohol, which has a molecular weight of 46 and is present in all
alcoholic beverages.  In the alcohol distillation process, the
lighter ethyl alcohol molecule gets over easily.  Water has a
molecular weight of only 18 so it comes across very easily in any
distillation. Alcohol and acetic acid also come across easily with
water, but molecules like gluten/gliadin are too heavy to be carried
over during distillation since the EBT coloring agent with a
molecular weight of 460 was not able to come over.  For comparison,
an amino acid, just one of the components that make a protein,
typically has a molecular weight in the range of 110 to 130.  Just
one amino acid is about double the weight of acetic acid.  In the
case of gluten and gliadin, we are concerned with proteins, which are
the result of linkages of many amino acids.  The part of the gluten
protein that is of concern to celiacs is gliadin. It is reported to
have 19 amino acids strung together in a very specific
arrangement.  During the process of distillation, gliadin is thus
very unlikely to get over since its molecular weight is almost 2500.
That's just the gliadin part of the protein in gluten.  The whole
gluten protein is therefore many, many times larger than the simple
acetic acid found in vinegar.  The EBT (with a molecular weight of
460) is relatively small when compared to the protein that we are
concerned with.
_________

The issue of cross contamination was not being addressed here.
However, cross contamination is a common problem when talking about
gluten.  In conclusion, one can see visually that the boiling process
of distillation does not allow heavy molecular weight molecules like
the gluten/gliadin proteins to be carried over into the product.  As
a chemist,  John is satisfied and will use vinegar that has been
distilled.  Distilled white vinegar is common in condiments like
mustard, ketchup, pickles, etc.  There is usually no issue over
cider, wine, balsamic, rice vinegars which should be safe if only
made from their basic starting material (like grapes/wine, rice,
apples, etc.). Be aware of "flavored" or "colored" vinegars that
could be contaminated with added agents. There are individuals who
are just inherently sensitive to all vinegar, beyond gluten. Look
carefully at the labels.

One member mentioned that she had learned that celiacs with yeast
intolerance may also be sensitive to vinegar and should avoid it (In
the book "Feast Without Yeast" by Bruce Semon, M.D., Ph.D.).  Note
that this is not proven research.  John commented that naturally
fermented vinegars may still contain the original yeast/fungi that
facilitated the fermentation.  However, if the vinegar is distilled,
the yeast will not be carried into the product since it is too large
to make its way over in the distillation process.  Yeast is a living
thing that contains many large proteins.

NEW: Important information  learned at the recent CSA/USA conference.
All the presenters laid the issue of pure distilled vinegar/alcohol
to rest, believing that the process of distillation eliminates
gliadin from getting through into the distillate.  Therefore, we
don't have to worry about pure distilled vinegar any more!! (with
exceptions noted below in terms of enhancements, additions, and malt)

Also, the single word "vinegar" on a label should indicate only cider
vinegar; this interpretation has not been previously understood by
all the celiac community, thinking that the word indicated distilled
vinegar.  This news is so helpful for all celiacs!  According to a
new 2001 publication from CSA/USA, "Grains+ Glossary", " 'vinegar' or
'apple cider vinegar' or 'apple vinegar' on a food label on a product
of the U.S. must be made from apples; CFR, Title 21, Section 525.825,
revised March 1995.  Note:  A segment of those on a celiac diet
report reactions to malt vinegar, distilled vinegar, recycled
vinegars, enhanced vinegars, stabilized vinegars and color added
vinegars. Avoid barley malt and wheat."

I am disappointed and frustrated that CSA waited so long to let us
know about this "new" labeling feature.  Going out to eat is so much
easier when we don't have to worry about vinegar in a salad dressing.
Just order a vinaigrette dressing; no more hauling a bottle with you!

Janet Y. Rinehart
Former President, CSA/USA, Inc.
Chairman, Houston Celiac-Sprue Support Group
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