solaris to Ian, Hannah, Daniela, Jono, Mark on 24 Jun 2013. This question was also asked by jayisbeast, vahily.
Ian Wilson answered on 24 Jun 2013:
Hi solaris and jayisbeast,
Great question! The heat that you feel when you eat a chilli isn’t caused by an increase in temperature – it’s just spiciness. That’s why they burn even when they’re cold. The burning is actually caused by a compound called ‘caspaicin’, which is inside the chillis’s cells. The highest concentration of caspaicin is found in the seeds, which is why you take the seeds out if you don’t want your chilli con carne to blow your head off!
Caspaicin is an irritant, so it causes pain and discomfort to any cells it touches. That’s why it hurts your tongue and why you have to wear gloves whilst touching REALLY hot chillis!
But why are chillis like that? What does it gain them to be so hard to eat? Well, animals that might eat a chilli will soon think twice before eating another one because of the pain they feel when they eat them! So it acts as a defence mechanism. Some of the only animals that can tolerate the spice are birds and this relationship has evolved for a reason. The birds get a source of food and when they fly off and poo somewhere else, the seeds from the chilli land on the ground and start growing somewhere new. So the burning chillis cause is used to ensure that the plants get spread as far and wide as possible.
Hope that answers your question,
Jono Bone answered on 24 Jun 2013:
Hi solaris jayisbeast and vahily.
Capsaicin is the chemical in chillies which makes them feel hot. The nerve cells that have the receptor to detect capsaicin also sense changes in temperature. When capsaicin binds to these receptore they are activated and they tell the brain there is a hot stimulus and it actually feels like your mouth is burning.The more concentrated the nerve receptors in a particular part of your body, the more sensitive that part is to capsaicin. That’s why getting chilli in your eye can be really painful.
Mark Hodson answered on 24 Jun 2013:
Hi solaris, jayisbeast and vahily,
it’s the chemicals in the chilli reacting with your nerve cells.
It always amuses me that the poor old chilli plant has spent countless years evolving a defence mechanism to put creatures off eating it and humans come along and eat it precisely because of the defence mechanism.
Shows you how bizarre humans can sometimes be.
Hannah Brotherton answered on 25 Jun 2013:
Hi solaris and vahily,
everyone is right about why chilies burn when we eat them……..but did you know they are most dangerous than we eve thought!!
Scientist have found out that capsaicin (the component of chilies that makes us burn) makes up the venom of a tarantula. So when a tarantula bites you, he is making your tissue ‘burn’ by spitting in chilies…..
I wonder if I ate one, would it taste like a chili lol
So nature has evolved so that chili is so spicy that it makes us not want to eat it, so uses it as a defence mechanism or nature has used it in venom, because it is that strong.
Maybe we should think twice before eating a chili again, if it is in venom :S
Daniela Plana answered on 25 Jun 2013:
Hi solaris, jayisbeast and vahily!
As everyone has said it’s a chemical called “Capsaicin” which makes chillies spicy or “hot”… did you know that currently the most common way of knowing how spicy a chillie or a hot sauce is is by tasting? It’s called the Scoville scale… They put a bit of the chillie in water with a bit of sugar and have specialised people taste it…. they then add more water and sugar until they stop feeling the “heat”… the more water they have to add, the spicier it is! The problem they have is that you build up a “resistance” to capsaicin… so the spicier you eat, you start feeling it less, so testers have to be replaced often!
A few years ago someone came up with an “electrochemical” (which is the bit of science I do) sensor to test hot sauces for how spicy they are… it was pretty cool hearing about all of this in a formal scientific conference!