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Home    Ανάπτυξη αναλυτικών μεθόδων με βάση τη φασματοσκοπία NMR για την ανίχνευση νοθείας ραφιναρισμένου ελαιολάδου με ραφιναρισμένο φουντουκέλαιο, τον ποσοτικό προσδιορισμό CIS-TRANS λιπαρών οξέων σε λίπη και έλαια και συστατικών της ρίγανης με φαρμακολογικές ιδιότητες  

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Identifier 000372234
Title Ανάπτυξη αναλυτικών μεθόδων με βάση τη φασματοσκοπία NMR για την ανίχνευση νοθείας ραφιναρισμένου ελαιολάδου με ραφιναρισμένο φουντουκέλαιο, τον ποσοτικό προσδιορισμό CIS-TRANS λιπαρών οξέων σε λίπη και έλαια και συστατικών της ρίγανης με φαρμακολογικές ιδιότητες
Alternative Title Development of analytical methods, based on NMR spectroscopy for the detection of refined olive oi adulteration with refined hazelnut oil, quantitative determination of CIS- and TRANS components in lipids and oil by 1H NMR spectroscopy at low magnetic fields, and derermination of phenolic compounds and triterpenic acids in oregano growing wild in Greece by employing 31P NMR spectroscopy
Author Αγιομυργιανάκη, Αλεξάνδρα
Abstract The present study refers to the development of analytical methods, based on nmr spectroscopy, for the detection of refined olive oil adulteration with refined hazelnut oil, the quantitative determination of cis and trans components in lipids and oil by 1h nmr spectroscopy at low magnetic fields, and the determination of phenolic compounds and triterpenic acids in oregano growing wild in greece by employing 31P NMR spectroscopy. The first analytical method was based on the phosphitylation of hydroxyl groups of phenolic compounds and triterpenic acids present in oregano with the appropriate phosphorus reagent and the subsequent detection of the phosphitylated compounds by employing 31P NMR spectroscopy. The analysis was based on spectral parameters of model compounds, determined in the present study. 1D (1H, 31P) and 2D (1H,1H-gCOSY, 31P,1H-HMQC) NMR spectroscopy was utilised for the assignment of model compounds with more than one hydroxyl groups. The present methodology was able to detect and determine quantitatively the triterpenic acids oleanolilc and ursolic as well as the following phenolic compounds: benzyl alcohol, borneol, carvacrol, thymol, ferulic acid, rosmarinic acid, chlorogenic acid, apigenin, naringenin, taxifolin, eriodictyol and cis-3-hexen-1-ol. In the second analytical method, NMR spectroscopy was employed for the detection of adulteration of refined olive oil with refined hazelnut oil. Fatty acids and iodine number were determined by 1H NMR, whereas 31P NMR was used for the quantification of minor compounds including phenolic compounds, diacylglycerols, sterols, and free fatty acids (free acidity). Classification of the refined oils based on their fatty acids content and the concentration of their minor compounds was achieved by using the forward stepwise canonical discriminant analysis (CDA) and the classification binary trees (CBTs). Both methods provided good discrimination between the refined hazelnut and olive oils. Different admixtures of refined olive oils with refined hazelnut oils were prepared and analyzed by 1H NMR and 31P NMR spectroscopy. Subsequent application of CDA to the NMR data allowed the detection of the presence of refined hazelnut oils in refined olive oils at percentages higher than 5%. Application of the non-linear classification method of the binary trees offered better possibilities of measuring adulteration of the refined olive oils at a lower limit of detection than that obtained by the CDA method. The third analytical method exploited, the methodology of shift reagents for the distinction of cis and trans unsaturation in oils and fats. The differential binding of silver ions (in the form of AgFOD) to cis and trans double bonds allowed the separation of the allylic and olefinic proton signals in the 1H NMR spectra of mixtures of cis and trans methyl esters of aliphatic acids and unsaturated triacylglycerol mixtures at low frequency spectrometers (300 MHz). Careful integration of the appropriate proton resonances in the recorded quantitative 1H NMR spectra afforded percentage concentrations in very good agreement with the actual values. This 1H NMR methodology was validated by analyzing AOCS Laboratory Proficiency Program GC samples containing various percentages of saturated, cis-mono unsaturated, and cis-polyunsaturated fat as well as trans content. This fast and relatively low-cost NMR methodology could be used on line for obtaining nutrition labeling compositional data (NLCD) required for fat-containing food products
Language Greek
Subject 1D/2D NMR
AgFOD
AgFOD
cis/trans double bonds
cis/trans διπλοί δεσμοί
fats and oils
multivariate statistical analysis
nutritional labeling of food products
polyphenols
διατροφική επισήμανση τροφίμων
λίπη και έλαια
νοθεία
πολυπαραμετρική στατιστική ανάλυση
πολυφαινόλες
ρίγανη
ραφιναρισμένο ελαιόλαδο
ραφιναρισμένο φουντουκέλαιο
τριτερπενικά οξέα
Issue date 2011-10-31
Collection   School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
  Type of Work--Doctoral theses
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