I received lots of passionate feedback about my article on pairing spicy food with IPAs (originally published by CraftBeer.com). In light of this “heated” debate between people who both love and hate spicy food, I thought a follow up on the science behind the sensation would help.
Spoiler alert: spicy is not a taste, it’s a mouthfeel. Just like the sense of touch on your skin, mouthfeel is the sense of touch in your mouth, and helps you detect pain, temperature, and textures. The key to detecting these sensations is your trigeminal nerve. To get a sense (see what I did there) of how this nerve works, let’s do a quick demonstration. Hold up three fingers on each hand with fingers pointing skyward, Girl Scout style so to speak. Now rotate them in to face one another and place them onto your cheeks with your pointer fingers laying on your temples, your middle fingers pointing to your nose, and your index fingers just below your lips (see picture above). You have effectively identified the location of your trigeminal (three branches, hence the prefix tri) nerve.
This baby packs a punch. This is the nerve that dentists numb up before drilling, that tells you you’ve bit your tongue, and that makes you cry when you are cutting onions. And yes, this is the nerve that signals to your brain that something is wrong when you eat something too spicy.
There are lots of teeny offshoots of the trigeminal nerve on your tongue and in your mouth, like live wires. When spicy food particles come along, like capsaicin from hot peppers, the capsaicin and the ends of the live wires (called receptors) connect and an electrical signal is sent to the brain.
That’s when things get interesting. You’ve probably experienced these symptoms when eating spicy food: sweating, runny nose, eyes watering, face gets hot and red. This is a classic response to pain, and just like on your skin, it happens in response to spicy food in your mouth.
In order to handle the pain, first we typically reach for something cold. That's because the same receptor for spicy also helps us detect heat. So our brains think, “Fight! Fight with cold!” And grabbing that chilled beer or ice cold water helps… but only temporarily. That’s because cold doesn’t break the connections between the capsaicin and the receptor. All it does is turn on a counter receptor for cold and the brain for a moment is tricked into thinking all is well. But as soon as the cold dissipates, the mouth is right back to feeling on fire.
Because spicy is a mouthfeel, not a taste, you need to combat it using mouthfeel techniques. In order to feel relief, you need to pull the capsaicin off the receptor. To do this, we need to understand a little bit about chemistry. Capsaicin is hydrophobic. For lack of a better analogy this means capsaicin is scared (phobic) of water (hydro). In terms of chemistry, this means that water will not attract the capsaicin away from the receptor. Which means that cold water and cold beer (which is mostly water), doesn’t do the job. You need something that has fat or oil in it, something that will woo the capsaicin away from that trigeminal receptor.
With that in mind, think about some of the culinary pairings across the world, thai coffee prepared with condensed milk to pair with thai hot curry, cucumber raita with Indian vindaloo, blue cheese dressing with buffalo wings. These notoriously hot dishes all traditionally served with something dairy based to offset the heat. In addition, the more spicy food you eat, the more you desensitize the nerve. Even from the womb, babies start learning tolerance to hot food if their mother constantly eats spicy food while pregnant. So in addition to techniques for dealing with a spicy emergency, you can also just eat something spicy every day to build your tolerance.
Then again, you might just love the burn. In which case you have mouthfeel and your trigeminal nerve to thank.