Chilli peppers contain capsaicinoids. Capsaicinoids are colourless, odourless and flavourless substances that make chillies seem hot. They do this by directly stimulating the pain sensors in the mouth. This can produce a burning sensation in the mouth, cause the eyes to water and the nose to run, and even induce perspiration. Capsaicin, the primary capsaicinoid, can produce blisters on the tongue when diluted to a concentration¹ of 1 drop in 100 000 drops of water.

Capsaicinoids are concentrated in the chilli's placenta, the white 'ribs' that run down the middle and along the sides of a pepper. The seeds are in close contact with the ribs and are also often hot. By removing the placenta and the seeds, one can considerably reduce the heat of a chilli.

Capsaicinoids do not dissolve in water and so drinking water does not reduce the burning sensation. For alleviating the burning, milk (because of the fats and proteins) and alcohol (will dissolve capsaicinoids) are more effective. It should be noted that since beer is mostly water (typically only 5% alcohol), it is not very effective in relieving the burning. Sugar is also effective in diluting the capsaicinoids.

Capsaicin can also be useful. It has been discovered that, when applied as a topical cream over several weeks, capsaicins are effective in reducing athritis pain and in the treatment of peripheral neuropathy².

Scoville Scale

The Scoville scale is an attempt to introduce a standard measurement of the pungency of chillies so that they can be compared. The scale was first developed in 1912 by Wilbur Scoville³. At first the scale was a subjective taste test but it later developed into the measure of capsaicinoids present in the pepper. The Scoville scale is the most widely used method of rating chillies.

The concentration of capsaicinoids, measured in parts per million (ppm) are converted to Scoville Heat Units. This concentration is measured by 1ppm is equivalent to roughly 15 Scoville Heat Units. Pure capsaicin measures in the region of 16 million Scoville Heat Units.

Which Chillies are Hot?

The hottest chilli ever measured, a habanero, scored over 500 000 on the Scoville Scale. As a naturally occurring substance the amounts of capsaicinoids vary from pepper to pepper, so that one habanero can be hotter than another from the same plant. However, over time, it has become possible to obtain average ratings for various types of chillies and therefore create a list of the hottest chillies.

The hottest chillies are given below. The numbers in parenthesis are the Scoville Heat Units:

• Habanero (100k-300k)- Capsicum Chinense cv.⁴ This chilli is native to the Yucatan Peninsula and the Caribbean. Habaneros are round and squat with a slightly pointed end and are deep red when mature. They have a sweet, plum tomato-apple flavour under the heat. They are best used fresh, dried or in powdered form.

• Scotch Bonnet (100k-250k)- Capsicum Chinense cv. Closely related to the habanero, the scotch bonnet is native to the Caribbean and can be found throughout the islands. They are irregularly shaped and range in colour from yellow to orange to red. They are generally used fresh or made into pepper sauces.

• Jamaica Hot (100k-200k)- Capsicum Chinense cv. Yet another relative of the Habanero and is also native to the Caribbean, especially Jamaica. They have a bell shape and colours from light green to orange/red. They are typically used in pickles, sauces or fresh.

• Thai⁵(50k-100k)- Capsicum frutescens. These are widely used in Thai cooking. Peppers are small and elongated and have a characteristic curl near the tip. They are normally dried or frozen.

• Cayenne (30k-50k)- Capsicum annuum. Cayenne Pepper comes from Central and South America and the West Indies. It is named after the Cayenne River in French Guyana. These chillies are usually long, thin and sharply pointed. It is said to have many medicinal benefits including improving digestion and stimulating circulation. It is often found as a powder and used as a spice in curries and chutneys. It is also available as capsules and tablets for use as medicine.

Further Reading

• Why Chillies are so hot

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¹ or lack thereof
² Damage to the peripheral nerves - the vast communications network that transmits information from the brain and spinal cord to every other part of the body.
³ Wilbur Scoville worked for the Parke-Davis pharmaceutical company.
⁴ Denotes a cultivated variant.
⁵ Also known as Thai dragons