Page 7 - PERIODIC Magazine Issue 6

but when you do you can get some really useful feedback”. redox system acts as a homogeneous redox mediator so that
Currently the main consumers of the product are those that the recorded electrochemical signal is proportional to the
grow the chilli and want to know the hotness of the peppers, organosulfur concentration present. Around 15.7 million
as well as source providers (companies that convert chillies tonnes of fresh garlic is produced worldwide each year and
into consumer products). different batches vary significantly in the strengths of their
flavour, so the development of such detection methods
ChilliPot sensors also present an engaging way to encourage are important to ensure that garlic concentrations are
schoolchildren to participate in practical science activities; standardised.
Professor Compton and his group regularly attend schools
and organise outreach events on ‘chilli science’. The work
produced by students at these workshops ranges from
relating the colour of chillies to their heat, the relationship
between the chilli anatomy (such as the pith, seeds and flesh)
and the local heat content, and the effect of aging on chillies.

The great success of the ChilliPot sensors triggered further
challenges from the food industry. Could turmeric, ginger or
garlic be similarly detected using electrochemistry to meet
industry needs? Successful sensors for all three are now
licensed by Oxford to ZP. The active ingredients in turmeric
and ginger (curcumin and gingerol respectively) can also be
detected through the use of carbon nanotube electrodes, in a Professor Compton and his colleagues now hope to use the
similar way to capsaicin in chillies. technology that they have developed to branch away from
the food industry and use electrochemistry in detecting
The standardisation of curcumin concentrations is of chemicals of particular interest to health professionals. “The
particular importance within the food industry, as expensive electrochemical detection of E. coli bacteria is something that
turmeric is often adulterated with compounds including the we’re interested in currently,” Professor Compton explained.
bright yellow but highly toxic lead chromate. “Another potential application of this research would be in
the detection of glutathione in saliva, which can be used as a
The garlic sensor uses a different electrochemical method biomarker for bipolar disorder. This is particularly exciting as
to that used in the detection of chillies, turmeric and ginger. a non-invasive technique.” These electrochemical techniques
Bromide ions (Br ) are oxidised to bromine (Br ) on the have been proven as reliable and relatively cheap detectors,
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surface of a platinum electrode. Br is then reduced by allicin the full scope of their potential is being explored and
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(a pungent species which gives garlic its characteristic smell, relationships with new users and backers are on-going.
making up around 70% of the thiosulfates present in freshly
chopped garlic), forming a sulfonic acid and regenerating
Br ions, thus completing the catalytic cycle. The Br /Br
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Periodic
The Magazine of the Department of Chemistry