O-o-oh, Baby, burn me so good with peppers.

What is it about spicy foods, with flavors lit from hot peppers, that just make us keep coming back like a moth to a flame?  The pain is just too good.  That’s right.  It is not the flavor, but the taunting pepper compounds sensation on our oral and nasal pain receptors. (1)

These compounds don’t produce sweet, salty, bitter, savory or sour tastes.  Instead, they react with our somatosensory system.  The somatosensory system, according to Google definitions, is a system “Relating to or denoting a sensation (such as pressure, pain, or warmth) that can occur anywhere in the body, in contrast to one localized at a sense organ (such as sight, balance, or taste)”. (2) So what actually happens to your tongue?

It all starts with the Trigeminal nerve.  The trigeminal nerve begins at the ear and branches off to the eye, nose, upper and lower jaws.  Stimuli is received through “chemesthesis”, or chemical reactions to sensations, [temperature, pain and pressure], not taste. These types of receptors reside in the skin as well as in the mucus membranes.  However, skin is thicker and tougher than the mucus membranes like the nostrils and the tongue. The top of the tongue, in particular, is spongy, chock full of receptors and absorbs the pepper compounds quite readily.  This is why champagne bubbles create a bigger reaction in the nasal passages than if spilled on your wrist during a toast and chili peppers burn the tongue, but not your fingers while being chopped for your favorite salsa.

What are the “pepper compounds”?  There are many including piperine (3)  which gives black pepper its piquant.  Allyl isothiocyanate is found in mustards and horseradish. This is stuff that not only gives you that wasabi nose rush, but is even combustible. (4) The most potent, capsaicin, [cap-SAY-i-sin], resides in chili peppers.  An interesting fact about all of these compounds is that they are oil based.  Oil and water don’t mix. Therefore, that gallon of H2O you downed after eating Thai Green Curry is fairly useless.  People will tell you to drink milk.  The reason milk is touted as a means to tone down the heat is due to the fat found in milk.  When you ingest some fat to cool down the heat, the fat surrounds the capsaicin and removes it.  If you slogged down some full fat soy milk it would have the same effect.  The margaritas you are having with your TexMex Diablo enchiladas can also soothe smoldering saliva.

Alcohol is chemically a cousin of petroleum.  Therefore, it having similar properties as the milk fat. (5)  However, it is also easy to mix with water or water-based substances such as lime juice, cranberry juice or soda.  So it doesn’t work as well as the fatty mock sour cream.  On the other hand, it is better than plain water and head and shoulders above effervescent soft drinks which disperse the burning pepper everywhere.

According to Drs. Mózsik, Vincze and Szolcsányi, there are four stages which change the neural receptors when exposed repeatedly to capsaicin. (6) First, “excitation”, next “a sensory blocking effect”, followed by “long-term selective neurotoxic impairment”, and ending with “irreversible cell destruction. “ Now you would have to do some serious scotch bonnet salsa to have irreversible damage, but many of us are held in bondage to the excitation and long-term selective neurotoxic impairment.

If your first spicy dish was vindaloo you probably thought your mouth was on fire and never looked back.  On the other hand, if your first was when you were very young or was a mild heat, your mouth was teased by the stimulation.  The seduction had begun.  Then, like a first kiss from a teen-puppy crush, we just want more.  We get used to so much stimulation that we need higher and higher amounts to keep us happy.  This is when we begin to deplete our neurotransmitters and enter the stage of sensory blocking effect.

Anyone who has been to a chili or salsa cook off will know the terms “catches up with you”, “first you taste the smoke, then you taste the heat”, “one hankie chili” or “a slow smooth burn.”  You can read similar descriptions on red wines with black pepper overtones or finishes.  Remember the neural provocation is akin to high heat or abrasive substances on your tongue.

Which brings me to the sweating that happens with eating jalapeño tofu scramble. Those trigeminal nerve fibers not only respond to pain, but temperature.  Over stimulation leads to false signals of temperature elevation.  Next thing you know moisture comes to the surface to cool you.  Not a bad idea when you are in the tropics, but pretty annoying on a romantic date.

But then, if you are having a romantic date where the food gives a little pain with pleasure, I think that’s all we need to know.  Bring on the chilies and leave the whip at home.

1 Retrieved on June 11, 2011 from http://www.psych.umn.edu/courses/fall06/davenportn/psy3061/hot_or_not.pdf

2 Retrieved on June 14, 2011 from http://www.google.com/search?client=safari&rls=en&q=somatosensory+definition&ie=UTF-8&oe=UTF-8#hl=en&safe=active&client=safari&rls=en&q=somatosensory&tbs=dfn:1&tbo=u&sa=X&ei=SaP4TZKnNef40gGXv4WKCw&ved=0CBkQkQ4&bav=on.2,or.r_gc.r_pw.&fp=955a9bf9013e7a3f&biw=1116&bih=627

3 Retrieved on June 12, 2011 from http://www.britannica.com/EBchecked/topic/461424/piperine

4 Retrieved on June 12, 2011 from http://www.chemicalbook.com/ChemicalProductProperty_EN_CB8853857.htm

5 Retrieved on June 12, 2011 from http://www.scienceclarified.com/everyday/Real-Life-Chemistry-Vol-2/Solutions-Real-life-applications.html

6 Mozsik G, Vincze A, Szolcsányi J. [2001] Four response stages of capsaicin-sensitive primary afferent neurons to capsaicin and its analog: gastric acid secretion, gastric mucosal damage and protection.  J Gastroenterol Hepatol. 2001 Oct;16(10):1093-7