April 16 : I have often met foreigners who say they enjoy spicy food but when they eat Indian curries their face turns red. I have also seen a bunch of American college kids devour fairly spicy kebabs without reaching for a glass of water.

Personally, I have low tolerance for chillies; what’s hot and spicy for me is mild for my family. During the “pickle season” in Mumbai my mother would dry green chillies in a tray on the windowsill till they turned red, and then throw the lot into burning oil. The smell was unbearably acrid. It made my eyes water — though the pickle was always delicious.
Recently, an American guest on his first visit to India said he had heard a lot about samosas and wanted to taste some. We alerted him to the risks of eating the spicy snack but he said he had lived in Texas and was used to hot food. Some foreign visitors tend to compare the spiciness of Indian pickles with brands of chilli sauce they have back home. “Of course, this is much hotter than that”, they add as they wipe the sweat off their face. There’s a scale on which chillies are graded, but I wish there was a chart that tells you how hot a brand of Indian lime or mango pickle is compared to, let’s say, the Classic Tabasco red pepper sauce.
In 1912, an American chemist, Wilbur Scoville, invented the method to measure the heat level of a chilli. The chemical that causes the burning sensation is capsaicin; the more capsaicin in a chilli, the hotter it is. Scoville powdered a chilli, mixed it in sugar syrup, and asked a group of people to taste it. He then reduced the quantity of capsaicin and asked the group to taste it again, repeating the process and reducing the capsaicin quantity each time. The point where it no longer burned was ranked as the heat quotient of that particular species of chilli. The measure is called the Scoville Heat Unit (commonly known as SHU). If a chilli is ranked at 5,000 SHUs, it means that’s the quantity of sugar syrup needed to dilute one part of chilli till its heat can no longer be felt.
The problem with the Scoville method, however, is that it’s not scientific. It relies on the taste buds of individuals. So in 1980s the test was replaced by a computerised method known as High Pressure Liquid Chromatograph that can calculate the concentration of capsaicin in parts per million. Its result is measured in ASTA units (acronym for American Spice Trade Association), but since Scoville units have been around for a very long time, the ASTA units are converted back to the Scoville scale (one ASTA equals 15 Scoville units).
So, sweet pepper with its 100 Scoville units is right at the bottom of the scale; at the top of the scale is pure capsaicin with a Scoville rating of 16 million. According to the Tabasco website, its red pepper sauce has 2,500 to 5,000 SHUs. In comparison, India’s Naga Jolokia (also called Bhut Jolokia), till recently considered to be the hottest chilli on earth, has a pungency of about one million SHUs. 
I say “till recently” because last week, a chilli grown in a greenhouse in Lincolnshire was declared the fieriest in lab tests: it’s been ranked at 1,067,286 on the Scoville Scale, hotter than India’s Bhut Jolokia (1,041,427). It’s been named the Infinity Chilli because “you cannot get rid of the burning sensation by even milk, said to be the best antidote”.
I checked a few chilli sauce bottles in our kitchen and the label on only the Tabasco Habanero Sauce mentions the word Scoville: “the legendary Habanero can bring tears to the eye, boasting a Scoville rating of 200,000+!” That, however, does not mean the bottle contains pure habanero.
I have come across references that our Indian green chilli or hari mirch contains 15,000 to 30,000 Scoville units, and the red chilli or lal mirch has 30,000 to 50,000. The delicious Sing Cheung Chilli Sauce made in the Chinese quarter of Tangra in Kolkata makes no mention of Scoville units, but then no one expects it to. The spicy Thai Chilli sauces are said to have a Scoville rating of 50,000-100,000. I don’t know what it takes to get a chilli tested for Scoville units but I would love to find out the “heat factor” of, let’s say, the Avakai pickle that I love but find impossible to handle.
Our American guest presented us a bottle of Texas Chipotle Pepper Sauce (brand name Suckle Busters). The bottle shows a “heat index” of medium on a scale of “mild to hot”. He was courageous enough to try out a samosa on his first trip to India. He had one bite and then another (out of politeness, I guess) and promptly reached for the ras malai. We changed the subject to Indian desserts.

By Shekhar Bhatia
Shekhar Bhatia can be contacted at shekhar.bhatia@gmail.com