Page last updated at 16:31 GMT, Monday, 27 October 2008

New heat tests for chilli sauce

A plate of chillies
The new test uses nanotechnology to measure the heat of chilli sauce

Chemists in Oxford have invented a new way of finding out how hot a chilli sauce is without tasting it.

The researchers from Oxford University have developed a technique to measure the levels of capsaicinoids - the substances which make chillies hot.

The technology could soon be available commercially, as a cheap disposable sensor for use in the food industry.

The current industry procedure relies on a panel of people tasting spicy foods and is therefore subjective.

"You might think we can all eat the hottest chillies," said Professor Richard Compton, who leads the research.

We can simply dip it into the sauce and we get an electrical signal which gives us a number
Professor Richard Compton
Oxford University

"But actually there is a number that you can ascribe to a sauce or even a curry in a restaurant that quantifies how hot the chilli content is.

"It is called the Scoville Unit and it requires a panel of no less than five allegedly expert tasters.

"They get a sample of the chilli and keep on diluting it until they can't possibly taste any more chilli there," he added.

The Scoville rating measures the number of dilutions. The higher the number, the bigger the burn.

The relatively mild Jalapeno ranges from 2,500 - 8,000, whereas the world's hottest chilli, the Naga Jolokia, has a rating of 1,000,000.

The new test uses carbon nanotubes and it gives a reading in less than a minute.

It uses similar technology as that used by diabetics to test blood sugar levels.

'Good fun'

"It is a simple little device based on nanotechnology," Professor Compton said.

"We can simply dip it into the sauce and we get an electrical signal which gives us a number, which matches up with the subjective Scoville units really rather agreeably well."

The researchers are now hoping to license the technology to an Indian food company.

"We have been looking at the chemical properties of nanotubes for a while, so the impetus comes from fundamental science," said Professor Compton.

The chemist said he did not think the new testing method would make him a millionaire. "But it's all good fun," he said.

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