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Tuesday, August 30, 2011

The Heat is On!

One of the foods that originated in the Americas is a member of the nightshade, or solanaceae, family - the chili pepper.  Pepper is a misnomer, as that refers to a member of the piperaceae family, such as black or white pepper.  But that's what Christopher Columbus thought it was, and so named it.  A physician from Columbus's second voyage to the West Indies, Diego Álvarez Chanca, took it back to Spain in 1493 and wrote about the medicinal effects a year later.

A ristra, or arrangement of chilis strung to dry.

There seems to be two main theories on how chilis got to Asia.  One is that the Spanish colony of Mexico was trading with the Philippines, and from there it spread to India, China, Korea, and Japan.  The other is that the Portuguese took it with them when they colonized the Goa region of India, where is it a prominent ingredient in the cuisine, and from there it spread through Asia.

Fresh ghost chili from a market in Assam, India.

What makes chilis so popular, and now an integral part of cuisine the world over, is its heat, or pungency. This is caused by capsaicin, a chemical compound, and coincidentally a topical analgesic.  Capsaicin stimulates nerve endings in the skin, especially mucous membranes.  It is a natural compound, related to vanillin (found in vanilla), eugenol (bay leaves, allspice, and cloves), and zingerone (ginger and mustard).
A habanero.

Capsaicin, when consumed, binds to the receptors in the mouth's lining.  They register the pain from the heat, and hence the burn.  This happens when calcium ions flow from one cell to the next.  It's not a coincidence that Latino foods are often served with sour cream or guacamole, or Asian curries have cream or butter in them.  Dairy products and fatty foods provide the most relief.  Water only spreads the pain.  Alcohol might help if it was 80%, but then would create a different kind of burn.

This stinging pain has not been ignored as a weapon.  The Mayans used to throw them at their enemies.  In northeast India and in Africa, they are used to keep wild elephants from eating certain plants and to restrict them from entering areas.  In fact, in 2009, scientists at India's Defense Research and Development Organization announced plans to use capsaicin in hand grenades as a non-lethal way to flush out terrorists and control rioters.  It has also been developed into a spray for self-defense.

But capsaicin also has serious medical uses.  Ghosts chilis, one of the hottest, are used in India for homeopathic medicines for stomach ailments, and to induce perspiration in hot weather.  Capsaicin can lower the sensation of pain in arthritis and other chronic conditions, such as herpers zoster, diabetic neuropathy, post-mastectomy pain, and headaches.  Capsaicin blocks the production of certain neurotransmitters, preventing nerves from communicating with each other.

The highest amount of capsaicin is found in the placenta of the fruit, and not in the seed as is commonly thought.  The seeds do have a bitter taste.  Although mammals can taste the pungency in chilis, birds can't, so it's a good thing to add to birdseed to prevent squirrels and other rodents from making off with it.  I've also diluted it with water and sprayed it on plants to keep rabbits and squirrels from eating them.  It works, but must be reapplied frequently.

Image courtesy www.chilepepperinstitute.org.

Measuring the capsaicin in a chili was a dilemma until pharmacist Wilbur Scoville came up with a test in 1912, which he called the Scoville Organoleptic Test.  He tried testing the reaction of capsaicin with other chemicals, but nothing was sensitive enough to register it.  What was sensitive enough was the human tongue. He was ridiculed by his peers, but continued with his experiments.

Bell peppers, which have no capsaicin.

He soaked each kind of pepper in alcohol overnight to extract the capsaicin.  This extract was added in increments to a sugar solution until the heat was barely detectable by the human tongue.  He used a panel of five people at the time, averaging their ratings.  The degree of the dilution is his scale rating.  A bell pepper, which has no capsaicin, has a rating of zero.  But a habanero has a rating of 200,000 or more, meaning it must be diluted 200,000 times before the capsaicin can just barely be detected.

This scale now needs to be upgraded with the new Guinness winners.
Image courtesy of www.benitoshotsaquce.com.

The problem with the scale is it is subjective, which makes it imprecise.  A new way has been developed which uses a machine which is claimed to be as sensitive as the human tongue.  This new method is called high-performance liquid chromatography (HPLC).  It directly measures the chemicals, which are expressed in ASTA (American Spice Trade Association) pungency units.  One part per million equals 15 SHU (Scoville Heat Units).  But getting people to switch has been as hard as getting the U.S. to use metric measurements, so ASTA figures are multiplied by 15, then reported in SHU.  Some spice experts say the figures can be up to 50% off, however.

HPLC equipment.

The Scoville scale can be used to determine the pungency of other substances, such as resinferatoxin.  This is a substance found in spurges, a plant used since ancient times as a laxative.  Resinferatoxin is 1,000 times hotter than capsaicin, so it would be expressed as billions on the SHU.

Growing the hottest chili is now a highly competitive undertaking.  In the Guinness Book of World Records in 2007, the hottest chili was the "bhut jolokia", also known as the "ghost chili", rating 855,00 SHU.  On February 20, 2011, Guinness awarded the title of "world's hottest chili" to the "Infinity" chili from England (1,067,266 SHU).  Five days later, on February 25, the record was broken by the "Naga viper" chili (1,382,118 SHU).  But on March 1, the record was again broken by the "Trinidad Scorpion Butch T Pepper" with a SHU of 1,463,700.  Who's next?

The Trinidad Scorpion Butch T chili, named for its scorpion-like tail.
Image courtesy www.thehotpepper.com.

One thing to be considered when looking at the Scoville rating is that the pungency of chili is greatly determined by the growing conditions - soil, humidity, and the quality of the seed.  Some chilis don't grow well "in captivity", and specimens of the same variety may rate significantly different.   I once grew some Anaheim chilis, known to be mild, and they were so hot I couldn't give them away, even to friends who prize very hot chilis.

Red savina pepper (580,000 SHU).

As far back as 7,000 BCE, chilis may have been first eaten in South America. Valued, spread throughout the area, and at one point used as currency, chilis now have a new currency in the race to breed the hottest one.

Unless otherwise noted, images courtesy of Wikipedia.
Chili has two recognized alternative spellings - chile and chilli.


  1. It was nice to find out how the Scoville scale works and that the placental part is the most hot while I viewed the lovely photos. I did always wonder how a native american plant got to Asia. But I am still puzzled why humans love to eat hot peppers!

    I may be wrong and have completely misunderstood: "But a habanero has a rating of 200,000 or more, meaning it must be diluted 200,000 times before the capsaicin can be detected." (needs to be ...capsaicin can NOT be detected...no?)

  2. Sorry, Michelle, it is unclear I guess. It should be that it must be diluted 200,000 x before it can just barely be detected. I, myself, can't stand much heat - it zaps my taste buds so I can't taste anything. But I do rub capsaisin on my body parts when there is pain and it works.