The study of measurement systems for the assessment of basic qualitative and compositional parameters, based on the interaction of electromagnetic fields with oil products

摘要

Capacitance and Time Domain Reflectometry (TDR) measurements were conducted to assess the basic qualitative and compositional parameters of extra virgin olive oils (EVOOs). Capacitance values obtained by a parallel plates capacitor in the frequency range of 1-9 kHz were used to build predictive models of the water content from 16 different commercial EVOOs by Partial Least Square (PLS) analysis. TDR signals were processed by Principal Component Analysis (PCA) to discriminate between EVOO samples produced with two olive cultivars ("Correggiolo" and "Canino") both characterized by different contents of fatty acids alkyl esters due to the different storage times of the olives. From PLS regression, R-2 values of 0.921 (RMSE=100 mg/kg oil) and 0.909 (RMSE=106 mg/kg oil) were observed for the prediction of the water content in cross and test set validations, respectively. PCA appeared to show differences between samples in terms of sum of fatty acid methyl esters and fatty acids ethyl esters within the same cultivar of olives. These first results are promising for the assessment of the EVOO parameters. However further studies should be conducted in order to better understand the relationship between the dielectric behavior and the EVOO composition.