Characterisation of olive oil by an electronic nose based on conducting polymer sensors

The selection and test of an array of conducting polymer sensors with extra-virgin olive oil samples is presented in this paper as a first step towards the development of an electronic nose dedicated to the detection of olive oil aroma. Different sensors produced by both electrochemical and chemical techniques were initially exposed to a set of pure substances present in the headspace of extra-virgin olive oil and meaningful for the evaluation of its overall organoleptic characteristics. Four sensors showing the best sensitivity to these standard substances were chosen to carry out further experiments on samples of commercial olive oil. Two different experimental set-ups and protocols for olive oil sampling were tested and compared, providing evidence on the best procedure needed to handle this foodstuff and on the possibility of using a dedicated sensing system for practical purposes in the olive oil industry. Three different extra-virgin Italian types of olive oil can be easily distinguished with an array of four sensors and it is also possible to detect changes in the aromatic content of the headspace after handling of the samples. Different samples of the same oil show reproducible responses.