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Direct study of minor extra-virgin olive oil components without any sample modification. ¹H NMR multisupression

Ainhoa Ruiz-Aracama¹, Encarnación Goicoechea¹, María D Guillén¹

¹Food Technology, Faculty of Pharmacy, Lascaray Research Center, University of the Basque Country (UPV/EHU), Paseo de la Universidad n° 7, 01006 Vitoria, Spain.

|March 21, 2017

Abstract:

Proton Nuclear Magnetic Resonance (¹H NMR) was employed to study monovarietal commercial Spanish extra-virgin olive oils (EVOO) (Arbequina, Arroniz, Cornicabra, Hojiblanca and Picual). Each sample was analyzed by a standard pulse and by an experiment suppressing the main lipid signals, enabling the detection of signals of minor components. The aim was to determine the possibilities of both ¹H NMR approaches to characterize EVOO composition, focusing on acyl groups, squalene, sterols, triterpene acids/esters, fatty alcohols, wax esters and phenols (lignans, tyrosol, hydroxytyrosol, oleocanthal, oleacein, oleokoronal, oleomissional, ligstrodials and oleuropeindials), and to determine hydrolysis and oxidation levels. The signal assignments (in deuterated chloroform) are thoroughly described, identifying for the first time those of the protons of esters of phytol and of geranylgeraniol. Correct signal assignment is fundamental for obtaining sound results when interpreting statistical data from metabolomic studies of EVOO composition and adulteration, making it possible to differentiate and classify oils.

Keywords:

1-Acetoxypinoresinol (PubChem CID: 442831)1-Tetracosanol (PubChem CID: 10472)24-Methylenecycloartanol (PubChem CID: 94204)Acyl groups Aldehydic phenols Beta-sitosterol (PubChem CID: 222284)Elenolic acid (PubChem CID: 169607)Extra-virgin olive oil (EVOO)Hydroxytyrosol (PubChem CID: 82755)Multisuppression experiments Oleacein (Pubchem CID: 18684078)Oleocanthal (Pubchem CID: 16681728)Proton nuclear magnetic resonance ((1)H NMR)Squalene (PubChem CID: 638072)Squalene and terpenes Sterols Tyrosol (PubChem CID: 10393)

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