Wilbur Scoville: What is the Scoville scale - and what is the hottest chilli in the world

The hottest chilli pepper in the world is the Carolina Reaper (2.2 million SHU)

The Carolina Reaper is the world's spiciest chilli (Getty Images)

As Google honours Professor Scoville's 151st birthday with his own doodle - here is everything you need to know about the man who figured out how to measure the heat of chillis.

How does the Scoville test judge the spiciness of a chilli pepper?

The spiciness of chilli peppers is measured using the Scoville scale and test and was invented by Prof Scoville in 1912.

The Scoville Organoleptic Test answers this specific question: How many equal parts of sugar water are needed to add to a ground chilli pepper until no distinguishable heat can be tasted?

According to the Smithsonian, an exact weight of ground dried pepper is dissolved in alcohol to extract the heat components.

This is then added to sugar water which is then sipped by five trained tasters.

Over a period of days, the taster will sip the steadily more and more diluted solution until they cannot taste the heat.

What does an SHU represent?

The spiciness of each pepper is measured in Scoville heat units (SHU) which represent the equal parts of water needed to prevent someone tasting the heat.

For example, Scotch Bonnet chillis (350,000 SHU) would need to be diluted up to 350,000 times to prevent someone tasting its heat.

What gives chillis their spicy heat?

First discovered in 1816, the ingredient producing spiciness in chilli peppers is a compound called Capsaicin.

This is a natural irritant to all mammals which produces a burning sensation on any tissue it comes into contact with.

It is used in pepper sprays to blind and incapacitate human and animal targets.

Pure capsaicin has a Scoville rating of 16 million SHU.

What is the hottest chilli pepper in the world?

Since 2013, the hottest pepper in the world has been the Carolina reaper.

This variety was created by South Carolina chilli farmer, Ed Currie, and achieved 2.2 million SHU.