Was reading about polyunsaturated fatty acids (PUFAs) and their receptors today.* Turns out that PUFAs activate TRPA1, the “cold” receptor on the trigeminal nerve in the mouth and nose. When activated, this receptor causes not only sensations of cold, but also of pain. TRPA1 also acts like a volume dial, initially enhancing the flavor of whatever activates it. However, in about a minute of continuous exposure to the PUFAs, TRPA1 becomes desensitized and ceases to be active.
Normally, the fats we eat come in the form of triglycerides, fatty acids attached to a glycerol backbone, or in the form of phospholipids, where two fatty acids are attached to a “head” structure that varies by the type of phospholipid. When the PUFAs are attached in this way they cannot activate TRPA1. But once they are free, they can. Microbes are experts at liberating PUFAs when they infest a food.
When fish spoils, it doesn’t just make the stinky amines that I discussed in my July 3rd post. Fish, especially cold water fish, have an abundance of PUFAs in their triglycerides and phospholipids. Once the microbes get going, a lot of PUFAs are released.
Neither mice nor humans enjoy the taste of these PUFAs. Flies, however, don’t seem to mind, because their TRPA1 receptors aren’t sensitive to them.
PUFAs are another reason why rotted fish is so unpleasant…but you can get used to it…
...or add lemon—lemon activates TRPV1 and turns off TRPA1... ; )
 |
| No, this fish isn't rotten...Photo by Gregory Bourolias, unsplash.com. |
* Motter AL, Ahern GP (2012) TRPA1 Is a Polyunsaturated Fatty Acid Sensor in Mammals. PLoS ONE 7(6): e38439. doi:10.1371/journal.pone.0038439.
No comments:
Post a Comment