Hot peppers have been around for as long as humans can recall, and for some cultures, they are part of their identity and heritage. But how much do you know about the science behind the spiciness in hot peppers? Well, get ready to learn about the chemical substance responsible for the fire in chilies: capsaicin.

In part one of this blog series we will give you a small overview; read all about what capsaicin is, where to find it and why it exists.

What is capsaicin exactly?

In a nutshell: capsaicin is a lipophilic compound that can be found in different concentrations in peppers that are described as hot, such as Habanero, Jalapeño, and Scorpion. It is a compound that produces a burning sensation in any tissue it comes into contact with. So, the more capsaicin in the pepper, the more the heat gets turned up.

Let's get into some history. Capsaicin was first extracted in 1816 by Christian Fridrich. Further work by John Clough Thresh led to its naming in 1876, but it wasn´t until 1898 that Karl Micko isolated the compound in pure crystalline form. A century later, in 1997, David Julius discovered and cloned the cellular receptor for capsaicin, and brought a new level of understanding on how capsaicin works. We´ll get more into this science in the second part of this blog.

Capsaicin has been utilized widely in all types of industries. We love to use it to spice up our taste buds, but we also use it in the military, pharmaceutical, and countless other industries. We are constantly developing new uses, due to its wonderful versatility.

“The more capsaicin in the pepper, the more the heat gets turned up.”

Where to find it?

Not surprisingly, capsaicin can be found in the fruit of capsicums. Capsicum is the genus of plants producing the fruits we call ‘peppers’. The term Capsicum is derived from the Greek κάπτω (kapto), meaning “to gulp.” This morphed into Latin capsa, meaning ‘case’, referring to the fact that peppers hold seeds.

These little seeds come in all sorts of colorful boxes, from the sweet bell pepper to the mighty hot Carolina Reaper. Many capsicums contain capsaicin, which is the substance responsible for the kick spicy food enthusiasts love and crave.

Within the fruit, capsaicin is present in the placenta of the pepper, the white pith the seeds are attached to, which we call ribs or veins. To a lesser extent, it can also be found in the other fleshy parts of the fruit. Contrary to what you might believe, the seeds themselves do not produce any capsaicin.

How capsaicin concentration is determined

The degree of heat found within peppers, also called pungency or piquancy, is determined by how it measures on the Scoville scale, recorded in Scoville Heat Units (SHU).

The Scoville Scale was developed in 1912 by Wilbur Scoville, a pharmacist from the United States. To determine the SHU, an exact weight of hot pepper is dissolved in alcohol to extract the capsaicinoids components. These components are then diluted in a solution of sugar water and decreasing concentrations are given to a panel of trained tasters until a majority can no longer detect them in a diluted form. The heat level is then rated based on this dilution in multiples of 100 SHU. This system was initially purely organoleptic but nowadays is measured using HPLC (high-performance liquid chromatography) to prevent any deviation from sensory fatigue or the chosen panel´s resistance.

So, why is it there?

Think of capsaicin as a powerful defence mechanism plants have developed to survive. The key about capsaicin is that it does not affect all species of animals or fungi. This is a brilliant evolutionary development that makes the existence of capsaicin twice as beneficial to the plant.

First off, capsaicin affects every animal species besides birds. These feathered friends don't experience the pain caused by capsaicin, which makes them the plants´ greatest ally in carrying seeds over long distances. This is a great example of evolution; it just makes sense to produce a compound that repels potential predators but does not affect your greatest seed carriers.

Even before being domesticated, six to eight thousand years ago, chilis had found a way to spread over more land and proliferate more widely by using birds as their seed carriers. Not only do birds fly and can spread the seeds over long distances but they also swallow the fruit whole, which keeps the seeds intact and allows them to germinate once they are “dropped”.

A growing chili pepper plant at one of our farms - UHCU Spice.png

The second detail is actually a very well known use for capsaicin: natural pest repellent! Once a plant starts growing, things are not rosy and fine all the time. In fact, the growing process is tough and plants have to survive all types of hardships; from extreme weather conditions to natural predators and getting enough nutrients. What if you could erase one of those hardships? Capsaicin is a natural repellent for insects and even fungi, so the fruit is more likely to develop and mature as it should.

Having said this, something as beneficial as capsaicin does not come without any trade-offs. Producing capsaicin takes a lot of energy, which is why some peppers are not spicy. In some cases it makes more sense to make a lot of fruit with less or no capsaicin, thus producing more seed, and getting offspring by overwhelming predators and plagues by sheer volume.

This is the first part of our blog series about capsaicin. Stay tuned to learn about how capsaicin works, why we love it so much, and how to help with a bad chilli burn.

Looking to spice up your products with hot peppers? Contact us, and we will gladly help you out. UCHU Spice carries several varieties in all presentations: brined, dried whole, in powder or flakes, and in mash both fermented and acidified.