Exploring the Relationship between HPLC/DAD/MSand Folin Ciocalteau (FC) Method for Minor PolarCompounds Analysis in Extra Virgin Olive Oil

Minor Polar Compounds (MPC) of 88 extra virgin olive oils were analysed by HPLC/DAD/MS and by Folin Ciocalteau (FC) spectrophotometric method which quantifies total polyphenols as gallic acid equivalents. The aim of this work was to validate and evaluate the linear association between FC and HPLC data. Data were analysed by Principal Component Analysis (PCA). The eigenvalues indicate that the first three principal components provide a good summary of the data, accounting for about 81.1%. The first component shows approximately equal loadings on almost all variables, with two remarkable exceptions: Lignans and Apigenin. Notably, the highest positive loadings involve FC, Deacetoxy-oleuropein Aglycone and Oleuropein Aglycone. The second eigenvector, on the contrary has the highest loadings on the variables Lignans (positive) and Flavonoids (negative). Here FC and diphenols (Deacetoxy-oleuropein Aglycone and Oleuropein Aglycone) shows extremely low loadings. It was concluded that FC can reliably estimate total MPC (especially diphenols) but cannot give information about valuable compounds such as lignans and flavonoids.