Talk about passing the sniff test ...
Want to know if that tuna salad from yesterday’s picnic is still any good? For now, you’ll have to use the nose on your face, but in the near future more sensitive “electronic noses” may be able to tell you whether to keep the fishy leftovers or chuck them.
These “noses” don’t smell the way we do -- in fact, most of the time they use color-changing molecules to show what they perceive -- but they can recognize things humans can’t smell at all, or can smell only faintly.
Chemistry professor John Lavigne’s lab at the University of South Carolina has developed such a color-changing detector for fish. The chemical sensor alters its hue in the presence of nitrogen-containing molecules, called amines.
When you whiff a questionably fresh food, your nose knows certain smells mean danger. In the case of bad fish products, it can smell the chemical histamine, which builds up in meat as the proteins decay. But because human noses are weaker those of many other animals -- which also rarely worry about forgotten Tupperware in the back of the fridge -- we sometimes can’t smell histamine until there are toxic amounts of it.
The South Carolina scientists say their artificial “nose” performs very well with tiny amounts of pure histamine, creating a tell-tale spike on a graph when the chemical is present. A harder test is whether it can also smell the histamine in a complex mixture, such as a piece of meat.
In their study, published online in the journal Organic Letters, the researchers did that test. They ground up tuna straight from the can with acid, then tested the watery layer with their histamine detector. They used known amounts of store-bought histamine to spike the fishy water and retested the detector’s accuracy. Even mixed with all that tuna goo, the artificial nose could still sense the histamine.
The scientists say their nose is better than a human nose at smelling amines; it showed significant changes in color when the levels of histamine in the fish slurry rose through “healthy,” “borderline” and “sickening” all the way to “deadly” amounts.
They suggest that a commercial version of the detector might someday cut out the guesswork for all of us.
-- Chelsea Martinez
