There are several ways to detect bad breath. The simplest is the tried-and-true sniff test, in which you breathe or cough into your cupped hands and then smell the result. However, this method doesn't always work very well, which is one reason why scientists are continually developing new and more accurate ways to pinpoint halitosis.
A team of investigators from Belgium and Italy recently unveiled a novel odor test in the Journal of Breath Research. Unlike other methods that rely on noses (human or electronic), this one uses the sense of sight to detect bad breath.
The group described creating a device that uses an enzyme taken from pea plants to signal the presence of two volatile sulfur compounds (VSCs), the molecules that give bad breath its unpleasant stench.
Researchers first derived a special enzyme from the Lathyrus cicera, a vegetable species also known as the red pea. Unlike edible peas, this plant is not for eating. Consuming it can lead to lathyrism, a condition of paralysis in the legs.
Still, the group found a practical use for the plant. They noted that its enzyme, if mixed with horseradish peroxidase and condensed in an acid bath, will turn pink in the presence of certain VSCs.
Essentially, it forms a bad breath litmus test.
In experiments, the group mixed the enzyme with saliva taken from volunteers. The pinker the resulting mixture, the more likely the participants' breath was to contain putrescine and cadaverine, two VSCs that also give rotten meat its distinct aroma.
If you worry that you have bad breath, there are other, cheaper ways to check. You can try swabbing the back of your tongue with a cottonball or scraping it with a white plastic spoon. If the residue you collect is yellow or smells odd, you probably have halitosis.
Likewise, oral health specialists can recommend a good specialty breath freshener if they detect VSCs in your mouth using a halimeter, a wand-like device used by many clinicians.