From: jil@uts.uucp (Jamie Lubin)
Subject: Re: Cooking food alters protein
Organization: Bellcore, Piscataway, NJ
Date: Tue, 29 Sep 92 13:50:55 GMT

In article <BvADEr.AoF@csc.liv.ac.uk> beynonrj@uxb.liv.ac.uk (Dr. R.J. Beynon) writes:
>>Lot of stuff about denaturing amino acids rather than protein...
>
>As a protein biochemist/enzymologist, can I make the following observations:
>
>The main issues here are twofold - 
>
>a. The word denature is being interpreted vaguely. A protein chemist
>   might use it differently to others - it means to destroy a proteins
>   folded shape - not to damage the building blocks (amino acids). 
>
>   When we want to break proteins into their amino acids, we have to use
>   conditions that prevent damage, particularly oxidation. Amino acids
>   such as tryptophan, methionine, threonine, serine, cysteine are
>   quite susceptible to irreversible, chemical damage, and it is reasonable
>   to accept that this will alter their nutritional value. 
>
>   So, cooking is the big undefined variable here:
>
>	How long, what temperature, what pH, what else is in the pot.
 
First of all, thanks for your comments!!  As far as the cooking variable is
concerned, I *assume* that the methodology is described in each scientific
journal article.  I don't have access to these, but some of you might.  In
fact, one was from the British Journal Of Nutrition.

>Also, a couple of general remarks. Cooking improves the digestibility of
>many foods, destroys some unpleasant components (e.g., in pulses) 
>and probably enhances our ability to extract nutrients from them.
>Try a meal of uncooked pulses, grains and leaf vagateables. I suspect
>that what is gained from the improved (?) amino acid content will
>be offset by other consequences. We've been cooking food for a long time,
>and without knowing about amino acids. I sort of believe that if cooking
>food had been bad for us, we might have given up a long time ago :-)
 
Definitely not a fan of abandoning cooking, although I do consume a lot of
raw fruits & veggies every day.  If you missed what began this whole thread:
I was defending (not recommending) my use of a supplement which contained,
among other things, a complete protein & that I'd been doing so for ~16 yrs.
I don't use supplements (in general) as a replacement for a poor diet, but as
part of a healthy lifestyle which includes eating properly, exercising &
avoidance of negative things (drugs, alcohol, tobacco, etc.).  In any case,
I mentioned that much of the protein in diets may be accompanied by a high
fat content.  I mentioned a couple of other things such as the quality of the
protein being more important than the quantity &, almost as an afterthought,
threw in that cooking alters protein.  Of course, I was referring to food as
opposed to pure amino acid concentrates in a lab setting.  In the least, I
am using supplements as a health insurance policy which has paid high dividends
to this point & will continue to do so as long as I'm pleased with my health.
To summarize, I'm not using a supplement because several scientific journals
state (correctly or otherwise) that heat/cooking alters protein, but because
it is part of my healthy lifestyle.  Now all this writing has made me hungry
so I'm going home to broil some chicken & I won't care if the lysine enters
my bloodstrem late & that it becomes a limiting amino acid ;-)

>"I am worried that I am getting 110% of my daily intake of protein"
 
I hope I'm getting that much...of course, I don't really know what *my*
protein RDA is (& I don't really care)!!
 
>Rob Beynon, Biochemistry, Liverpool

I once lived in Liverpool, NY!! (outside of Syracuse).
Newsgroups: sci.med.nutrition,talk.politics.animals