Thursday, August 17, 2017

What's in my burger? -- proteomics edition!

In case you also weren't aware, there is a video game App called "What's in my burger?" I discovered it while looking for images for this post. The goal appears to be to lure unsuspecting animals to bounce into the "BurgerMaker 3000".  I saw a description that called it "funny and horrifying at the same time". There is no space on my old phone, so I have to take their word for it.

With that out of the way -- time for seriousness!

Food counterfeiting is a serious big deal. The FDA is right down the road from me and they deal with this stuff all the time. I just heard a fantastic story about a company they busted that was attempting to utilize left-over leather as a food additive....yeah....I hear this stuff and I'm saddened that global industrialization has gotten to a level that we need a bunch of highly trained scientists constantly testing our food supply to make sure no one fills it full of poison to save $1 on each 100 kg of food they import. I'm consistently glad that we have these scientists!!

It turns out proteomics can make a significant impact in this field! Check out this new paper. 

This team applied a standard quadrupole-Orbitrap proteomics approach (however -- using 75uL/min! not nanoflow! yay!) to a bunch of different meats mixed together in different combinations. You'll note the proteogenomics mention in the title. They whittled down their FASTA database to focus on animal muscle and to remove sequences with 100% homology.

With this technique, they show they can determine when 1% of the wrong animal tissue is present in the sample -- honestly, it looks to me like they could do better than this as well. After this success, the authors conclude that more targeted quantification methods should be developed here for routine monitoring, but I'm not sure I agree. The ongoing battle between the FDA and U.S. customs with food importers and manufacturers has been described to me as an "arms race." Businesses motivated by that $1/ 100kg savings employ their own scientists who have the job of coming up with any way they can to circumvent these testing rules.

In 2007 a manufacturer/importer found a way around some simple quality tests for protein content in rice protein for animal food (I'm pretty sure it was a colorimetric assay that reacted to N-terminal amines, but don't quote me) by spiking in melamine and this additive (or chemical reactions with this additive) killed thousands of dogs in the U.S.

As an incredibly biased person and admitted dog fanatic, I don't see how developing a targeted MRM assay for some peptides is much different than the colorimetric assays. I get offers in my inbox to synthesize any peptide I want at lower and lower rates every week. I think that if you give me a couple days and some motivation I could beat a peptide MRM based food quality assay. A global HRAM MS/MS based one? That's gonna be a whole lot harder!

I do like this study and if you put me in charge of determining food contamination/adulteration this is exactly the method I'd run with.

(This post reminded me there hasn't been a dog pic on here in a while. Bernie's great at cleaning jars!)

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