Monday, April 30, 2007

back to melamine (or, why you need organic- and biochemistry)

the melamine contamination of pet food and the subsequent discovery of contamination of hogs is all over the news (and in class!). but, what is melamine and why is it important?

as reported in today's NYTimes:
For years, producers of animal feed all over China have secretly supplemented their feed with the substance, called melamine, a cheap additive that looks like protein in tests, even though it does not provide any nutritional benefits, according to melamine scrap traders and agricultural workers ...
well, here is melamine (from Acta Cryst., 2005, E61:o222-o224), some of it's uses include manufacturing heat-resistant handles for pots (and toasters!), cutlery, dishes and flooring.

note the many nitrogen residues, most importantly the primary amines (-NH2). It both mimics the peptide bond (C-N) and has three primary amines; both of which may react with the reagents in the most common protein assays (look here). You can see, that even directly measuring nitrogen (by near-infrared spectroscopy) would result in an inflated estimate of crude protein!

a friend reminded me of the 'olden' days, when unethical feedstuff purveyors would use urea to increase the apparent protein content of their product.

so; what is lethal about melamine? it's hard to say. toxicological reports are equivocal. it is also a distinct possibility that the melamine added to the feed was, itself, contaminated. perhaps by formaldehyde, or other compounds used in its synthesis. in addition, since much of the melamine came from scrap traders, perhaps there was contamination in the recovery/grinding process.

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G. F. Barbato said...

between 2.5 and 3.0 million chickens in Indiana have been reported as being exposed to melamine. about 100,000 birds have been, reportedly, condemned

G. F. Barbato said...

a new report in the NYTimes summarizes new developments in the melamine-pet-food-case. Notably, the general manager at one of the two companies implicated in using melamine has been arrested.

Secondarily, officials in Alabama and Missippi (sic) have pulled catfish, imported from China, from the shelves after finding antibiotic residues in the frozen fish!