Chillies come in many shapes and sizes, from the tiny bird’s eye chillies which are hot enough to burn your mouth, to larger milder varieties. A good rule is the smaller the hotter. Be careful of the chillies that are bright red and only one or two centimetres long.

Chillies are the fruit of plants which belong to the Capsicum family. They originated on the American continent where they have been an important part of the diet for approximately 9,500 years. Chillies may have been the first crop to be grown for human consumption in Central and South America, according to evidence from pre-historic sites in Ecuador that date back 6,000 years.

When Christopher Columbus arrived in America in 1492, he came across the fruit and called them chilli peppers because they were hot to the taste like the black and white pepper already known in Europe. Unlike the pepper used in Europe, however, chilli peppers were cheap. In 15th century Europe, black pepper was so expensive it was used as money in some countries. After Christopher Columbus introduced chillies to Europe they became highly prized for flavouring food. They were also used in medicines, especially for the relief of pain.

Chillies gradually spread along the established trade routes to Asia, India and South East Asia, transported by Portuguese and Arab traders.

Nowadays, there are probably 400 different kinds of chillies produced around the world with India being the world’s largest producer, consumer and exporter. This is not surprising for anyone who has eaten a hot Indian curry. However, India is not necessarily, the home of the hottest chilli. The title of hottest chilli ever grown is hotly contested by many countries such as Britain, Mexico and Trinidad as well as India.

But how can the hotness of chillies be accurately measured? In 1912, an American chemist called Wilbur Scoville invented a scale which measures the concentration of heat producing chemicals in chillies. He originally developed the scale by tasting, but now computers can do the job more accurately. The mildest chilli, the sweet green pepper used in salads is rated as 1 unit. In 2012, the hottest chilli ever recorded was rated at over 2,000,000 Scoville units. Chillies of this strength cannot be eaten. They are classed as weapons-grade and they are used in the pepper sprays that police use to fight crime, control violent crowds and stop criminals.