Chilli Chemistry 101.

Here we go with the science behind why our mouths seem on fire when we eat chillies…

Individual chilli varieties, plants, pods and even parts of pods all contain varying amounts of capsaicinoids. These are the compounds responsible for the hot sensation when we eat chillies. Capsaicin is the main capsaicinoid found in chillies, although there are others. Inside a chilli fruit, the highest concentration of capsaicinoids can be found in the join between the membrane lining of the chilli wall and the whitish pith where the seeds are attached. This is where the capsaicin glands lurk, waiting to ambush an unsuspecting cook.

Each part of the chilli pod has different levels of capsaicin.

The capsaicinoid compounds share a significant quality. They are able to enter and alter the TRPV1 ion channel in mammals. They lock the receptors open until the capsaicinoid molecules have moved on. TRPV1 receptors are responsible for detection and regulation of body temperature over 42 degrees. The receptors can be found at many points within mammals bodies, and are particularly sensitive where there are mucus membranes. When we eat chillies, it is the TRPV1 receptors in our mouth that respond with the oh so familiar burning sensation. Capsaicinoids trick our body into thinking we have touched something dangerously hot.

Is it just chillies, or do other plants produce capsaicinoids?

There are some real bad ass plants out there. Resin Spurge (Euphorbia poissonii) for example produces a compound that is up to 1,000 times more potent than capsaicin. So pungent that even in tiny amounts it renders the recipient seriously neurologically damaged, and can be fatal. Luckily for chilliheads, capsaicin levels found naturally in chillies do not cause physical damage, just a physical response.

Resin Spurge Euphorbia poissonii

Another member of the Capsaicinoid Gang can be found in ginger: gingerol. It measures lower on the Scoville Scale than capsaicin which explains the milder seeming heat of ginger. It fact gingerol becomes even milder if cooked long or at a high temperature. Be warned though, as a gentle warming or drying of ginger can double the spiciness of gingerol.

Foodies will also be familiar with the aromatic heat of peppercorns. This is caused by a capsaicinoid called piperine. Perhaps it was the early love of piperine that allowed the capsaicin rich chillies to steal our hearts when they were finally unleashed on the old world.

There are also other capsaicnoids to be found in chilli peppers. Nonivamide is one of these. It is synthesised and used in the food industry to add pungency and heat. It is cheaper to do this than extract and use naturally occurring nonivamide or capsaicin. It is also the main constituent of pepper spray.

Why have capsaicinoids developed in plants?

Most people seem to agree that it is in the interest of deterring mammals. Plants do not want to be eaten by animals that will destroy their seeds. Simple but are there other reasons too?

What about animals? Do they use capsaicinoids?

It turns out that the animals have got the hang of making chemical triggers for the TRPV1 receptors too. Certain tarantulas of West Africa, specifically the Earth Tiger tarantula, make a toxin that works on the TRPV1 receptor causing pain in the form of intense heat.

Earth Tiger tarantula

Obviously Mrs Earth Tiger doesn’t want to be chewed up and spat out by a furry mammal. Not so good for future generations of baby Earth Tigers. Chemical weapons at the ready then.

The use of capsaicin as a deterrent is not only employed by plants but by used by humans as well. The aforementioned pepper spray is a good example of this. And, a quick look at an image taken from the Codex Mendoza, created in the mid 1500s, reveals a child being held over a fire of burning chillies. The child’s eyes are streaming. It is perhaps a punishment: a deterrent for some undesirable behaviour. Y’owch, tough love but they’ve gotta learn!

Taken from the Codex Mendoza



But back to the chilli plant’s use of capsaicin as a deterrent…

The biological motivation of chilli plants is a little more complex. Many plants are interested in animals eating their fruit as a manner of seed dispersal. But chilli plants are producing a chemical that actively deters mammals. So what is wrong with mammals? Ah, they have grinding molars. Poor little chilli seeds are unlikely to survive after a good grinding. Most mammals will avoid plants which make their mouth burn so the chilli seeds are safe to be eaten by non-mammals.



It turns out that birds are just the insensitive little blighters required… insensitive to capsaicinoids that is. It makes sense that chilli plants don’t deter their feathered friends as birds’ feeding habits are exactly exactly what a chilli plant needs. Bird sees brightly coloured, yummy looking fruit. Bird eats fruit. Seeds pass through digestive system pretty much intact. Bird flies off. Seed deposited with a healthy dose of Mother Nature’s own fertiliser. Job’s a good’un.

That sounds like the right reason for capsaicinoids to be in chillies.

Ah, but animals are not the only consumer of chillies. Microbial level interference is just as likely to stop the chances of a chilli plant producing viable seed as hungry animals are. Fungi and bacteria in particular are able to negatively affect chilli plants’ growth. Which leads to the revelation of another super power of capsaicinoids. They are highly anti-microbial.

It has been theorised and widely accepted that wild chilli plants survive to produce ripe seed pods when their pods have a higher dose of capsaicin lurking within. This capsaicin presence seems to deter certain fungus from taking up residence in the plants and affecting their crop.

Other capsaicinoids deter different fungi in a range of ways. Some act on fungi on the roots, others on fungi on the leaves. The percentage and balance of capsaicinoids present in individual species of chillies correlates with exposure to specific fungus. So Ecuadorian rainforest chillies have different capsaicinoid levels to Andes Mountain rocoto chillies as a result of the microbes present in their respective environments.

Chillies are super anti-bacterial. Capsaicin inhibits the growth and survival of about 75% of bacteria out there in the world. Once the chilli plant has reached maturity it has a high enough concentration of capsaicinoids to inhibit bacterial attack. Bang, and the germ is GONE!

The anti-microbial quality of capsaicinoids goes a long way to explain why chilli is a very popular traditional ingredient in hot countries. Back in the days before fridges, the anti-bac effect of chillies would have stopped food from spoiling. Recipes would have included chilli as a preservative and preventative to food poisoning. Good recipes are always passed down. Bad recipes might have resulted in no one surviving to pass recipes down to.

It’s beginning to look like a lot like chillies and their capsaicinoid compounds are rather well equipped to take over the world with their tailor-made toxic toolkit. Oh, too late, they already have.

With such potency to be found in these compounds there must a be a way for modern humans to utilise the power of chilli.

Initially, when the portuguese explorers brought chillies home they were appropriated by monks and grown as a medicinal herb. What on earth did they use them for and what could they be useful for these days? Listed below are a few medical and health claims, not substantiated, just an indication of the impact capsaicin could have in our future:

Consumption of chilli before a meal can significantly reduce calorie intake. Capsaicin has an effect on the ‘fullness’ receptors in our stomach.

Topical application of capsaicin loaded creams can alleviate arthritic pain, shingles neuralgia and even HIV neuropathy. The Aztec folk used it as a pain reliever for toothache. The capsaicin is said to deplete the quantity of Substance P (one of the body’s pain messengers).

Capsaicin has been touted as a dietary control for cholesterol. Targeting the bad cholesterol that clogs up arteries whilst leaving alone the good stuff that clears them.

Psoriasis lesions that itch can be alleviated by the application of capsaicin creams. This pain relief is temporary but improves with regular use.

Eating a normal amount of chilli in a meal can reduce the quantity of insulin required by your body to deal with the intake of sugars.

The heat pain from a chilli can distract the body from other pain, e.g. migraine.

Capsaicin is also heralded as an anti-cancer hero. It can cause cancerous cells to go into defence mode and self-destruct in their efforts. Thus causing a halt in growing tumours.

Increased blood flow and thinning qualities as a result of eating chillies, all mean that heart disease and stroke are less likely.

Generally, people who eat chillies are 13% less likely to die before those who don’t eat chillies. Perhaps 100% true.

So why did humans develop a taste for chillies, despite the burn?

Maybe as a survival technique. It has been indicated that in the past, if you lived in an area where you are at risk of microbial infection and ultimately death, increasing the use of chillies reduced fatality. Communities who use more chilli in their cooking survived to tell the tale.

And then there is the chilli high. The body’s endorphin rush response to the attack of chillies. The thrill seekers and risk takers will recognise similarities in the rollercoaster of emotions a hot chilli hit brings compared to that of their thrill of choice. We feel good that we survived the chilli onslaught. We’ve survived to eat another mouthful of the hot stuff. It feels good to be alive!