The pet food recall scare continues unabated; a couple weeks ago, people were pointing at aminopterin, a folic acid analogue, which was covered here. Now, people are pointing fingers at melamine as a potential contaminant.
Melamine is a pretty simple compound, with a number of uses. Here, it’s being reported that it’s used as a fertilizer, which contaminated some wheat gluten, which ended up in the pet food. Despite the fact that you mostly get carbohydrate from wheat flour; gluten is actually a pretty inexpensive protein source. It’s mostly eaten in Asia, but some vegans have picked it up over here; if you’ve ever eaten seitan, that’s the stuff. You can actually make your own – just take some flour, a little salt, and enough water to make a yeastless bread dough. Keep playing with it under running water, and, eventually, you’ll be left with mostly gluten. Note that contamination is believed to be to blame, not gluten itself.
Melamine isn’t particularly toxic, but it has been implicated in kidney problems, which have been noted in the affected animals.
Melamine can also be polymerized with formaldehyde and sodium bisulfite, producing a very hard polymer (if you’ve ever used “melmac” plates, this is the stuff. It’s analagous to Bakelite plastic.
If polymerizing melamine resin is blown, you end up with a very light, fire-retardant foam with pores on the order of tens of microns across. The first two characteristics – weight and fire retardation – make it useful in airplanes and cars.
Awhile back, some people using melamine foams noticed that the combination of a hard plastic in a finely-textured foam made a pretty good cleaning product. If you’ve ever used “Magic Eraser” type products, this is what they are. It’s pretty amazing how the combination of water and the right abrasive can remove pretty much anything (including paint from walls, I note with some frustration).