Repositori URV

Identifier: TDX:778

Handle: https://hdl.handle.net/20.500.11797/TDX778

Authors:
Guimet Vila, Francesca

Abstract:
Olive oil contains fluorescent species, such as vitamin E, chlorophylls and oxidation products produced due to degradation. For this reason, fluorescence measurements can be used to obtain information about oil composition. This information can be obtained from direct measurements without needing any prior step of dilution of addition of reagents. This has great advantages with respect other techniques that require these steps, such as chromatographic, because no additional residues are generated and time of analysis is reduced. However the possibilities of fluorescence applied to olive oil analysis are not well studied and this technique is not normally used by the laboratories of olive oil quality control. The current instrumentation allows recording a set of fluorescence spectra at several excitation wavelengths in one measure. As a result, a fluorescence excitation-emission matrix is obtained. Mathematically, fluorescence matrices are matrices of numbers and are called second-order data. Chemometric methods applied to second-order data are called three-way methods, because the data are arranged in a three-dimensional structure. The objective of this thesis has been to characterize olive oils on the basis of excitation-emission fluorescence spectroscopy (EEFS) and three-way methods.The first part of the thesis includes the application of three-way exploratory methods of analysis to a set of commercial oils (virgin, pure and olive-pomace). The methods applied were unfold principal component analysis (unfold-PCA), parallel factor analysis (PARAFAC) and hierarchical cluster analysis (HCA). These methods enabled to distinguish between the oil types on the basis of their fluorescence matrices. PARAFAC has the advantage of providing the underlying spectra of the main famil