User:Jonathan Cline/Notebook/Melaminometer/Toxicology Background
Scientific American Magazine (2007)
Protein Pretense; August 2007; Scientific American Magazine; by Alison Snyder; 2 Page(s)
Traditionally, food protein is measured by a method developed by Danish brewer Johann Kjeldahl in the late 1800s. In this analytical technique, a strong acid digests a sample, breaking down the organic matter and releasing nitrogen, which is then converted to ammonia. The amount of ammonia indicates how much nitrogen was in the original sample and, hence, the amount of protein. This "proved to be a robust, precise method," says Julian McClements, a food scientist at the University of Massachusetts Amherst. It is attractive because it can be used for a variety of products and protein types. Another, similar nitrogen-based technique, called the Dumas test, is also popular with industry. It relies on burning the sample to release nitrogen. The Association of Analytical Communities (AOAC) International, a scientific association that sets standards for analytical methods, lists the Kjeldahl and Dumas techniques as the standard methods for measuring protein in food.
After hundreds of dogs and cats fell ill this past spring [Spring 2007], government officials traced the source to melamine, a nitrogen-rich compound found in plastics and fertilizer that, when ingested by the animals, crystallized in their kidneys and caused renal failure. The U.S. Food and Drug Administration later announced that producers may have deliberately added the compound to wheat gluten and rice protein concentrates to inflate the measured amount of protein. The greater the protein level in the concentrates, the higher the market price the products fetch. Regardless of whether its addition was deliberate or accidental, melamine snuck past standard industry protein analysis, suggesting that the century-old test methods should be reevaluated. Several alternatives exist, but the food industry has yet to make a switch.
Washington Post (2007)
Science and Medicine: Melamine David Brown and Robert Poppenga Washington Post Staff Writer and Veterinary Toxicologist Tuesday, May 8, 2007; 11:00 AM
Dr. Poppenga is a board-certified veterinary toxicologist and is currently a professor of clinical veterinary and diagnostic toxicology at the University of California at Davis. He is also the section head of toxicology at the California Animal Health and Food Safety Laboratory and has been actively involved in investigating pet and livestock exposure to melamine and other contaminants found in wheat gluten and rice protein concentrate imported from China.
Robert Poppenga: It is unlikely that melamine itself is causing the pet illnesses. The current thinking is that melamine in combination with cyanuric acid (another contaminant in the wheat gluten and rice protein concentrate used in the pet foods) may be responsible, although this has not been proven. There is no reason to add melamine to pet food - melamine is believed to have been added to the wheat gluten and rice protein concentrate to artificially increase their content of nitrogen (and as a result their apparent protein concentration). The more protein in the material, the higher the selling price.