Low resolution nuclear magnetic resonance (NMR) relaxometryrevealed that triglycerides in extra-virgin oliveoils are organized in inverse-micelle-like supramolecularstructures held together by weak interactions such as vander Waals and hydrogen bonding. The formers can be establishedamong the external apolar tails, while hydrogenbonds are present among the internal polar triglycerideheads, involving also the polar minor constituents of extra-virgin olive oils. The supramolecular assembly has beensupported by experiments conducted by heating the samplesin the NMR probe at four different temperatures. Inaddition all the oils were also added with increasing amountsof glacial acetic acid (AcOH). NMR relaxometry data atroom temperature revealed that T1 values increased withthe amount of the added AcOH. Moreover, it was noticedthat when the volume of acetic acid was around 20 % ofthe sample volume, a separation between an oily layer andan acetic acid phase was achieved. The latter appeared tocontain from 50 to 80 % of the total amount of the minorpolar constituents of extra-virgin olive oils (i.e. polyphenols,chlorophylls, sterols, some terpenes and so on). Suchfindings were interpreted with a conformation re-arrangementof triglycerides from ordered supramolecular inversemicelle-like systems to micelle-like leading to formationof emulsions. Based on the results of the present study, itcan be suggested that extra-virgin olive oils are not disorderedand amorphous liquids but systems whose constituentsare arranged in tidy supramolecular aggregates. Thecompartmental evidence of the minor polar extra-virginolive oil components may pose new questions about theirabsorption pathways in the human nutrition.
|Numero di pagine||6|
|Rivista||Fresenius Environmental Bulletin|
|Volume||Vol 19/ No 9b|
|Stato di pubblicazione||Published - 2010|
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