Varietal discrimination of extra virgin olive oils by near and mid infrared spectroscopy

The use of near and mid infrared spectroscopy, combined with chemometric analysis, was explored as a tool to classify samples of Italian extra virgin olive oil on the basis of the cultivar.A total of 82 monovarietal samples (‘Casaliva’, ‘Leccino’ and ‘Frantoio’) of extra virgin olive oils were analysed. Several variables were measured: the free acidity, the peroxide value, spectrophotometric indices, the fatty acid composition, carotenoids, chlorophylls and tocopherol content. The same samples were also scanned by using NIR and MIR spectroscopy. The classification methods (LDA and SIMCA) were applied on chemical data and on the spectral data after having used the algorithm SELECT, as feature selection technique. The results showed that NIR and MIR spectroscopy is an interesting technique compared with traditional chemical index in classifying olive oil samples on the basis of the varietal origin.The spectroscopic methods could represent a reliable, cheap and fast classification tool, not requiring chemical analyses for discrimination among cultivars.