When it comes to the sensory aspects food, we mostly consider characteristics like taste, texture, and temperature. But something we rarely talk about is the physical feeling it leaves us with, and when we do, it’s typically regarding spiciness. The sensation we don’t discuss very often is numbing.
Very few foods have this analgesic effect, but they do exist, and when used properly, just like any great ingredient, they can be absolutely delicious. Some of these items are readily available, while at least one is a little trickier to get a hold of, but they’re all fascinating in their own way.
Sichuan (or Szechuan) pepper, is a spice commonly used in the Sichuan province of China. It’s not actually a form of peppercorn or chile pepper, but is rather the husk of the seed of the prickly ash shrub (which belongs in the citrus family). The seed itself is tossed, as it’s not worth eating. The husks are typically a reddish brown, sometimes a pink color, and sort of look like a miniature Pac-Man.
I never ate Sichuan pepper in anything until well into adulthood, and am still kicking myself for not having tried it sooner. It has a bright citrus zest-like flavor that’s followed by a sensation that I would describe as tingly, and others call numbing (though not as numbing as a trip to the dentist’s office). Popular dishes containing Sichuan pepper include spicy hot pot broth, laziji (often called Chongqing chicken), and dan dan noodles.
Ever try anything seasoned with five-spice? Then you’ve had Sichuan pepper, though its flavor isn’t quite front and center in that mix. (Five-spice powder is comprised of cinnamon, fennel, clove, star anise, and Sichuan pepper.)
Combined with potent chile peppers, you get a seasoning known as mala. Mala is a combination of the words “numb” and “spicy” in Chinese, and it’s something everyone needs to try at some point. Because of the Sichuan pepper’s numbing effect, you might be able to handle more spice than usual. Where once you may have been timid, you will be a champion of conquering spice, going back for more helpings of anything seasoned in mala. Frankly, it’s awesome.
But how exactly does this all work? Sichuan pepper contains a compound called hydroxy-alpha-sanshool (sanshool for short). Smithsonian Magazine explains that sanshool doesn’t quite function the same way as capsaicin, the compound that causes the effects we feel from spicy food. Sanshool makes it feel like there’s a continuous tactile stimulation while you’re eating it, which accounts for that buzzing sensation many people report after eating Sichuan pepper.
I also asked Subha Ranjan Das, an Associate Professor of Chemistry at Carnegie Mellon University, for some more insight into sanshool. He says:
There are multiple sanshools—the Japanese pepper has at least four sanshools (alpha-, beta-, gamma-, and delta-), and two hydroxy sanshools (alpha- and beta-) and among these the main component responsible for the numbing and anesthetic effect is hydroxy-alpha-sanshool.
While sanshools trigger the same thermal receptor as capsaicin to a certain extent (so it does feel a bit spicy or hot), hydroxy-alpha-sanshool particularly can also affect other receptors that activate tactile neurons, hence the tingling effect.
One study by neuroscientists from University College London found that the feeling you get from eating Sichuan pepper happens within tactile receptors called Meissner’s corpuscles, which are responsible for transmitting the feeling of fine vibrations to your brain in hairless areas of your body, like your mouth. The researchers had subjects rub Sichuan peppercorn on their bottom lips while using a small vibrating mechanism on people’s fingers, and had people compare the sensation. They found that people consistently said that a 50 Hz vibration was closest to what they felt in their lips, essentially equating to 50 tiny pulses per second.
Das also notes that not all varieties of Sichuan pepper act the same. “There are different flavors and tastes, and these typically arise from the different sources, varieties, and their age,” he says. “Japanese sansho pepper is green and citrusy while the red Sichuan peppercorn is more floral. In all these there will be differing amounts of the various sanshools, so some may be more spicy hot, some may be more numbing.”
A long time ago I had the opportunity to try an ingredient called a buzz button during a fine dining meal. It was a small yellow flower bud perched on top of the dish, and after I chewed it up (it had a grassy, herbaceous flavor), my entire mouth felt like it was being electrified with one continuous shock. I’d never had anything like it.
Buzz buttons, also sometimes called the toothache plant or Sichuan buttons (they’re unrelated, but named so because of the similar buzzy feeling), are the flower of the Acmella oleracea plant. It’s native to tropical regions like South America, Africa, and certain parts of Asia.
The chemical responsible for its numbing qualities is called spilanthol. A paper published at ScienceDirect describes spilanthol as a “bioactive compound that is found in many different plants that are used as traditional remedies throughout the world.”
“Its leaves and flowers have sensory properties (pungency, tingling, numbing, mouth-watering) that make it a popular spice and ingredient in several Brazilian dishes,” the paper explains. Das points out that the chemical structure of spilanthol in buzz buttons is very similar to sanshools in Sichuan pepper. That means the tingling and numbing sensations will feel pretty similar between the two.
Due to its numbing properties, spilanthol has been used for toothaches. It’s extracted from buzz buttons and turned into a concentrate called jambu oleoresin, which is used for flavoring and for therapeutic purposes. The National Collaborating Centre for Environmental Health of Canada has a pretty interesting paper on buzz buttons covering its uses.
Buzz buttons aren’t something you can find at the grocery store—you can pretty much only buy them online at specialty retailers. For a short period, bartenders and chefs were using them as a novelty ingredient; Saveur reported on the trend back in 2015.
While cloves aren’t known primarily for their numbing properties, they contain a compound in them called eugenol. Eugenol is the main scent and flavor agent in clove oil, but it also has numbing properties. Like the spilanthol in buzz buttons, eugenol has been historically used as a remedy for dental issues.
“Eugenol from cloves can affect the receptor that causes feelings of warmth and can cause tingling and numbing sensations (though this is at fairly high amounts, say using clove oil) and they do have an anesthetic effect,” says Das. An interesting fact he added was that eugenol can desensitize the effects of capsaicin.
Clove cigarettes (oh, my college days), which originate from Indonesia, include a mixture of cloves, tobacco, and other ingredients. The eugenol in cloves allowed you to take some pretty hefty drags, since it cools off your upper airways as you smoke it. Note the past tense: the FDA banned clove cigarettes way back in 2009, along with other flavored cigarettes, save menthol.
In the amount you get by eating cloves in, say, pumpkin-spice foods, you won’t feel the numbing effect. But you can get clove oil from specialty retailers, along with Indian or Middle Eastern grocery stores, and dab it on your gums if you’ve got a burgeoning toothache. It won’t solve the issue (go to your dentist!), but it might give you a little bit of relief until you get into that chair.
If you’re curious about the numbing effect of some of these ingredients, I highly recommend you go get some Sichuan takeout. It’s the most accessible in terms of prepared food (I wouldn’t just go downing a bunch of cloves for experimentation’s sake). The spicier the Sichuan dish the better, if you ask me. Bask in some delicious numbing culinary bliss.