Cheating The Pet Food Industry’s Protein Tests

During the pet food recalls, many pet food owners wondered why the pet food companies did not test for melamine and melamine-related compounds in their ingredients. We asked ourselves would all of the recalls have been avoided and all of our pets’ lives been saved if they had included these in their testing?

How do the industry protein tests work? Traditionally, food protein is measured by a method developed by Danish brewer Johann Kjeldahl in the late 1800s. (Time for an updated test, perhaps?) In this method, a strong acid digests a sample which breaks down the organic matter and releases nitrogen. This is then converted to ammonia. This amount indicates how much nitrogen was in the original sample and, thus what is the amount of protein. One food scientist says this is a “robust, precise method.” This test can be used for a variety of products and protein types.

Another nitrogen-based technique called the Dumas test is popular with the industry. The method burns the sample to release nitrogen. The Association of Analytical Communities (AOAC) International lists the Kjeldahl and Dumas techniques as the standard methods for measuring protein in food.

The problem with these two nitrogen-based tests is that they assume that the nitrogen in food is protein constructed from nitrogen-based amino acids. This is fine if unadulterated food is being tested because the other major parts of food, carbohydrates and fats, do not contain nitrogen. Since the tests measure the total amount of nitrogen from both protein and nonprotein, they do not measure the true amount of protein.

This can make it easy to cheat the two tests. In the pet food recalls, nitrogen from melamine could not be distinguished from amino-acid nitrogen and contributed to the total protein in the sample.

From Scientific American:

Several alternative, non-nitrogen-based protein tests exist, such as laboratory chromatography and ultraviolet spectrophotometry, but they are expensive and time-consuming and require extracting protein from food, a process that differs depending on the type of food. For rapidly analyzing food protein, “probably the best technique,” McClements says, is infrared spectroscopy, which relies on the peptide bonds in proteins absorbing infrared light in distinguishable ways. The method demands that each chemical to be screened first be run to calibrate the machine; if researchers are not looking for a particular chemical, they will not find it using infrared spectroscopy. The appearance of a nonprotein spike would indicate a possible contaminant in the sample that could then be identified through other tests.

The Canadian Grain Commission adopted near-infrared reflectance (NIR) technology, a type of infrared spectroscopy, for screening its grain supply some 30 years ago. Since then, the U.K., Australia, Russia and Argentina, among others, have also switched to NIR. More than 90 percent of wheat worldwide is screened with NIR, according to Phil Williams, a consultant at PDK Grain in British Columbia and an early adopter of the technology for use in the grain industry. In principle, NIR could measure protein in a variety of food types, including wheat gluten and rice protein concentrates.

Still, some doubt that NIR could economically replace the nitrogen-based tests. Carl Schulze, president of New Jersey Feed Lab, a Trenton-based company that analyzes food for industry, states that NIR works best when one type of feed is being tested repeatedly. But the high initial cost of setting up the machine and running samples that are similar to the products being tested means that the technique may not be a viable alternative for the independent laboratories that test the food supply.

Thus far pet food makers and other processors have not decided whether to adopt new methods. “We’re in the process of building a feed safety protocol,” says Ron Salter, a vice president at feed distribution company Wilbur-Ellis in San Francisco. He adds that the company will be looking into feed sampling and testing procedures. In the meantime, nitrogen-based methods will likely remain top dog among protein-testing techniques.

For more analysis and opinions of the industry protein tests, here is a post on Itchmo forums from Offy, an Itchmo reader.

(Thanks Offy)

5 Responses to “Cheating The Pet Food Industry’s Protein Tests”

  1. Liz says:

    Thanks for all the information. You are providing a great resource. Our cats were better off when we just let them catch their own food!

  2. Moonbeam says:

    I had a premonition about the protein listed in the pet foods. One day, before all this broke loose, I was reading the ingredients on the back of a dog food bag and thinking - just how do they get so much protein in this bag - I have a hard enough time when I home cook getting the protein levels up there??????

  3. Captn'Carl says:

    Cheating on the protein tests aside, there is a much more serious potential problem looming on the horizon, if it has not already been put into play here.

    Labeling. Does anyone seriously think that the Chinese or any of the dozens of middlemen in the chain of products entering or made in this country would not be labeled as required while still containing the toxins that bring us here today?

    Look at all of the counterfeit Gucci bags, DVD,s Designer jewelry and fragrances that are manufactured and sold here every day!

    Think these individuals would not resort to proper labels with improper contents?

    This is a nightmare waiting to happen. Would you put it past any of them?

    I certainly would not.

    This is the next progression of events. If it has not happened already ( and I find that hard to believe), it will. Nobody has bothered to test properly labeled products yet have they? Why not?

    So much more the case if there were an intentional ulterior motive to this entire business.

    Someone recently wondered why our food supply has not yet been tampered with. Well? What do you think?

  4. Ann H says:

    I’ve already found Timberwolf feline to have WAY too much fiber and less protein than labeled. I have more cat poop now :) (normal) now that they’re on another food.

  5. Katie says:

    Cheating on the protein tests - it seems that with all the technological expertise in this country..that there would be a standardized test, easily used by every company dealing in proteins. With this being a new world after 9/11, how can we be prepared for future acts against us, if we can’t find out what is in food? And, added to this, our goverment has signed on to accept “unknown” products from third world countries so corporations can make greedy profits, and those profits come from unsafe food.

    Captn’Carl; you make a good point about labeling. I’m sure that is taking place now.

    Moonbeam: I agree totally; when I look at the bags of food now and see protein%’s, I wonder also, how did they calculate that. The food I fed when analyzed by CT agri. in 2002 - measured 9gm’s of protein/serving the lowest of 75% of dog food they tested and yet the bag says it provides 25% Protein. I never could figure out why my dog couldn’t put weight on and was losing hair by the handfull. Now that you all have steered me to research on what is in dog food - I believe the food protein calc. same from landfill garbage. I wonder how much protein is in styrofoam?? Now when I feed my dog homecooked and she gets 4oz of lean protein meat/serving, her daily protein is 44% and usually between 41 - 60 gms! This was quite an eye opener for me!


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