Detection of virgin olive oil adulteration using low field unilateral NMR

The detection of adulteration in edible oils is a concern in the food industry, especially for the higher priced virgin olive oils. This article presents a low field unilateral nuclear magnetic resonance (NMR) method for the detection of the adulteration of virgin olive oil that can be performed through sealed bottles providing a non-destructive screening technique. Adulterations of an extra virgin olive oil with different percentages of sunflower oil and red palm oil were measured with a commercial unilateral instrument, the profile NMR-Mouse. The NMR signal was processed using a 2-dimensional Inverse Laplace transformation to analyze the transverse relaxation and self-diffusion behaviors of different oils. The obtained results demonstrated the feasibility of detecting adulterations of olive oil with percentages of at least 10% of sunflower and red palm oils

Monitoring of virgin coconut oil (VCO) adulteration with palm oil using fourier transform infrared spectroscopy.

Virgin coconut oil (VCO) may be adulterated with cheaper oils, such as palm oil (PO). Thus, the detection and quantification of VCO adulteration with PO was monitored using Fourier transform infrared (FTIR) spectroscopy, combined with chemometrics of partial least square (PLS) and discriminant analysis at frequency regions of 3,010–3,000, 1,660–1,650 and 1,120–1,105/cm. Attenuated total reflectance (ATR) measurements were made on pure VCO and that adulterated with varying concentrations of PO (0.5–50% w/w in VCO). PLS calibration exhibited a good relationship between actual and FTIR-predicted values with coefficient of determination (R2) of 0.999 and standard error of calibration of 0.533. The cross validation was performed by removing one standard at a time, and the final R2 value of 0.996 and standard error of prediction of 0.953 were obtained. The discriminant analysis using seven principal components was able to classify pure VCO and that adulterated with PO

Rapid methods of oil quality assessment based on synchronous fluorescence spectroscopy

Fluorescence has been widely used in the analysis of organic compounds in pharmacy, food and environment. It is very sensitive with low detection limit contrary to vibrational spectroscopic technique and nuclear magnetic resonance. Molecular fluorescence is not suitable for the analysis of complex multi-component samples without prior separation, due to severe overlaps of excitation and emission bands. In such cases, synchronous fluorescence spectroscopy could prove beneficial as both the excitation and emission monochromators are scanned simultaneously in such a manner that a constant wavelength interval is kept between emission and excitation wavelengths (Δλ). Using suitable Δλ, synchronous fluorescence reduces spectral overlaps by narrowing spectral bands and simplifing spectra. In this study, novel spectroscopic methods for olive oil quality assessment and authenticity using chemometric methods are presented. Furthermore, methods for monitoring edible oils deterioration during thermal stress are shown. These methods are compared to classical assays. […]Η φθορισμομετρία έχει ευρεία εφαρμογή στην ανάλυση οργανικών ενώσεων στον τομέα των φαρμάκων, τροφίμων και του περιβάλλοντος. Σε αντίθεση με τις δονητικές φασματοσκοπικές τεχνικές και τη φασματοσκοπία πυρηνικού μαγνητικού συντονισμού, έχει υψηλή ευαισθησία και χαμηλό όριο ανίχνευσης. Η φθορισμομετρία μειονεκτεί σε περιπτώσεις όπου τα δείγματα περιέχουν πολλές φθορίζουσες ουσίες λόγω αλληλοεπικαλύψεων των φασμάτων διέγερσης και εκπομπής. Στην περίπτωση αυτή απαιτείται διαχωρισμός. Εναλλακτικά είναι δυνατή η χρήση της τεχνικής φθορισμομετρίας σύγχρονης σάρωσης. Στην τεχνική αυτή οι δύο μονοχρωμάτορες διέγερσης και εκπομπής σαρώνονται ταυτόχρονα ενώ διατηρείται σταθερή η διαφορά του μήκους κύματος διέγερσης και εκπομπής, Δλ. Με την κατάλληλη επιλογή του Δλ επιτυγχάνεται μείωση του εύρους των κορυφών και απλοποίηση του φάσματος εκπομπής. Με την τεχνική αυτή μειώνονται οι αλληλεπικαλύψεις των φασμάτων και μπορεί να αποφευχθεί το στάδιο του διαχωρισμού. Στη διατριβή αυτή παρουσιάζονται νέες φασματοσκοπικές μέθοδοι εκτίμησης ποιότητας και αυθεντικότητας παρθένου ελαιολάδου με τη βοήθεια χημειομετρικών μεθόδων. Γίνεται επίσης παρακολούθηση διάφορων βρώσιμων ελαίων κατά την θερμική καταπόνηση ή και ακτινοβολία UV και τα αποτελέσματα συγκρίνονται με τις κλασσικές μεθόδους προσδιορισμού οξειδωτικής κατάστασης. […

Spectroscopic techniques and chemometrics in analysis of blends of extra virgin with refined and mild deodorized olive oils.

The capability of different spectroscopic techniques in estimation of adulteration of extra virgin olive oil with mild deodorized and refined olive oils was investigated. The visible absorption and ultraviolet-visible fluorescence spectra were distinctly different for oils of different quality grades. Differences in the near- and mid-IR absorption spectra were less pronounced and could only be revealed by principal component analysis. The calibration models for estimation of adulterant oil in the blends obtained using partial least squares (PLS) and principal component regression (PCR) showed similar performance using all of the examined spectroscopic techniques. The simultaneous analysis of combined spectra using concatenated matrix did not improve the calibration results. The prediction parameters for the set of 20 samples were: R2>0.96, the relative error of prediction (REP) was in the range 5.6-12.0%. The RPD (ratio of the SD of reference values to RMSEP) were in the range of 5.1-10.9, indicating that all models were at least suitable for quality contro

Classification of edible and lampante virgin olive oil based on synchronous fluorescence and total luminescence spectroscopy

Journal URL: http://www.sciencedirect.com/science/journal/0003267