Abstract
Fourier-transform infrared spectroscopy, followed by multivariate treatment of the spectral data, was used to classify Tunisian extra virgin olive oils (EVOOs) according to their cultivar. Moreover, these data were also employed to establish the composition of binary mixtures of EVOOs from different cultivars. For this purpose, the spectra were divided in 20 regions, being the normalized peak areas within these regions used as predictors. Using linear discriminant analysis, an excellent resolution between EVOOs from different cultivar was obtained. Moreover, multiple linear regression models were used to predict the composition of binary mixtures of EVOOs, being in all cases capable of predicting the percentage of one of the oils with average validation errors below 6%. Thus, the FTIR method proposed in this work, followed by chemometric analysis, could be used in an industrial setting since no complicated laboratory facilities are required, which could save great deal of time and money. Practical applications: EVOO quality can be affected by different parameters, such as cultivar and maturity index, among others, consequently, it is necessary to develop analytical methods able to verify EVOO quality, and also to control its origin since olive oil producers have to include in their manufactured products the cultivar (monovarietal oils) from which the oil was obtained. Currently, almost all the research related to Tunisian EVOOs has been mainly focused on the improvement and characterization of the two main cultivars (Chetoui and Chemlali). Thus, to diversify Tunisian olive oil resources and improve the quality of olive oil produced in Tunisia, research on additional cultivars needs to be conducted. Thus, the present methodology (including the application of chemometric techniques) could be used as an authentication tool for olive oil industry to assess cultivar of EVOO.