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From: gamble@rice.edu (Ben Gamble)
Newsgroups: sci.bio,rec.food.cooking
Subject: Re: Mayonaise (Homemade)
Message-ID: <9931@brazos.Rice.edu>
Date: 18 Jul 90 01:25:49 GMT
References: <629@iss-rb.SanDiego.NCR.COM> <38422@sequent.UUCP> <1990Jul12.172710.9926@calgary.uucp> <3845@kitty.UUCP>
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In article <3845@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes:
|In article <1990Jul12.172710.9926@calgary.uucp>, parker@cpsc.ucalgary.ca (Jim Parker) writes:
|> 	2. Raw white, when ingested, prevents the body from
|> 		absorbing biotin. This can cause a deficiency.
|> 		This is what I think is the problem, and is
|> 		prevented by ONLY using the yolk.
|
|	I don't believe this is correct.  It is my understanding that
|spontaneous biotin deficiency (which is quite rare) has been observed
|in cases where people exist on a diet consisting *primarily* of raw
|egg whites and *little else* for a long period of time.

Begin excerpt, _Principles of Biochemistry_, White et al., 1978,
McGraw-Hill.

Biotin deficiency cannot be produced merely by diets deficient in this
nutrient, presumably because of intestinal bacterial synthesis of this
compound.  Biotin deficiency follows either sterilization of the
intestinal tract, feeding raw egg white, or administration of biotin
antimetabolites.

Shortly after the description of the effects of feeding raw egg
white, it was demonstrated that raw egg white contains a glycoprotein,
avidin, that combines with biotin and prevents its absorption from the
intestine.  Avidin (MW=70K) consists of four identical subunits each
with 128 residues of known sequence.  Each subunit can bind biotin
with Ka=10^15.  Denaturation abolishes the biotin-binding capacity.
[...] Avidin has been useful experimentally as an inhibitor of
biotin-containing enzymes.

End excerpt.

Ka=10^15, of course, means binding is practically permanent.

As for what measures you should take with your mayonnaise, anything I
could say would be only speculation.  But scarfing large quantities of
raw egg whites without biotin supplements is likely to make you sick.
(The symptoms of biotin deficiency are dermatitis and muscle aches, or
in more severe cases, paralysis.)

|> So what are we discussing?
|        Beats the hell outta me...

Well, it seems to have started out as mayonnaise recipes, which were
requested by someone allergic to hen eggs who planned to use duck eggs
instead.  Seems to have mutated into "Eggs as Biohazard", though.  (-;


Ben Gamble                     |     "It's a Cat!"  "In a Hat!"
gamble@owlnet.rice.edu         |     "You will note/ I am neat;
Bruce@Tiny[many]               |      wiped my feet/ on the mat."