Nanotubes get saucy

Oxford University chemists have found a way of using carbon nanotubes to judge the heat of chilli sauces. The technology might soon be available commercially as a cheap, disposable sensor for use in the food industry.

Prof Richard Compton and his team at Oxford University have developed a sensitive technique to measure the levels of capsaicinoids, the substances that make chillies hot, in samples of chilli sauce.

The current industry procedure is to use a panel of taste-testers, and is highly subjective. Prof Compton’s new method unambiguously determines the precise amount of capsaicinoids, and is not only quicker and cheaper than taste-testers but more reliable for purposes of food standards; tests could be rapidly carried out on the production line.

The well-established Scoville method – currently the industry standard – involves diluting a sample until five trained taste testers cannot detect any heat from the chilli. The number of dilutions is called the Scoville rating. The relatively mild Jalapeño ranges from around 2,500-8,000, whereas the hottest chilli in the world, the 'Naga Jolokia', has a rating of 1,000,000. High performance liquid chromatography (HPLC) can also be used but this requires bulky, expensive equipment and detailed analysis of the capsaicinoids.