Hot, hot, hot

Carbon nanotubes measure the hotness of chilli.

Oxford University researchers have developed a sensitive technique that can measure the level of hotness in chillies. The technique rates the intensity of ‘capsaicinoids’ in the chilli sauce that makes it hot.

The findings, published in the Royal Society of Chemistry journal The Analyst, could be made commercially available as a cheap, disposable sensor for the food industry.

In the method, developed by Richard Compton and his team at Oxford, capsaicinoids are adsorbed onto multi-walled carbon nanotube (MWCNT) electrodes. The team then measure the current change as the capsaicinoids are oxidised by an electrochemical reaction. This reading can be translated into Scoville units.

The industry standard Scoville method is the number of dilutions that a chilli product undergoes before a taste tester cannot detect any heat. The rating varies from the relatively mild Jalapeño ranges, around 2500-8000 dilutions, to the hottest chilli in the world, the “Naga Jolokia”, which has a rating of 1 million.

The Oxford University technique is called adsorptive stripping voltammetry (ASV), and is a relatively simple electrochemical method. Compton said, “ASV is a fantastic detection technique for capsaicinoids because it’s so simple - it integrates over all of the heat creating constituents because all of the capsaicinoids have essentially the same electrochemical response.”

The team tested their patent pending technique starting from the mild ‘Tabasco Green Pepper’ sauce to ‘Mad Dog’s Revenge’, which has an extensive health warning and liability disclaimer.

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