Quality assessment and authentication of virgin olive oil by NMR spectroscopy: A critical reviewt (original) (raw)
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Quality Assessment of Olive Oil by 1H-NMR Fingerprinting
Olive Oil - Constituents, Quality, Health Properties and Bioconversions, 2012
The information contained in this chapter reflects the authors' views; the European Commission is not liable for any use of the information contained herein.
1H and13C NMR of virgin olive oil. An overview
Magnetic Resonance in Chemistry, 1997
The authentication and quality assessment of virgin olive oil were performed using high-resolution 1H and 13C NMR spectroscopy. An overview of the various determinations currently assessed is presented with emphasis on the detection of adulteration with foreign (seed) oils and esteriÐed or reÐned olive and olive-pomace oils. Recent results on the NMR analysis of natural compounds (diacylglycerols, free fatty acids, aldehydes, polyphenols, etc.) related to the quality-freshness of virgin olive oil are also reported. The possible contribution of high-resolution NMR to the authentication of geographical origin of virgin olive oil is discussed.
Journal of agricultural …, 2007
The present study was designed to assess the agreement between analytical methodologies based on 1 H and 31 P NMR spectroscopy and conventional analytical methods (titration, gas chromatography, and high performance liquid chromatography) for measuring certain minor and major constituents (free acidity, fatty acids, iodine value, and phenolic compounds) of olive oil. The standard deviations of the NMR method were comparable to those of the conventional methods, except perhaps those of the total hydroxytyrosol and total tyrosol. Linear regression analyses showed strong correlations between NMR and conventional methods for free acidity, total hydroxytyrosol, total tyrosol, total diacylglycerols, (+)-pinoresinol, (+)-1-acetoxypinoresinol, and apigenin; good correlations for linoleic acid, free hydroxytyrosol, and free tyrosol; and weak correlations for oleic acid, linolenic acid, saturated fatty acids, and luteolin. Furthermore, a method comparison study was conducted and the agreement between NMR and conventional methods was evaluated by using the Bland and Altman statistical analysis. The distribution of the data points in the bias plot showed that 96.4% and 100% of the measurements of free acidity and iodine value, respectively, were within the limits of agreement of the two methods. For the remaining constituents of olive oil, the percentage of measurements, located within the limits of agreement, ranged from 94% to 98.5%.
Journal of Agricultural and Food Chemistry, 2007
The present study was designed to assess the agreement between analytical methodologies based on 1 H and 31 P NMR spectroscopy and conventional analytical methods (titration, gas chromatography, and high performance liquid chromatography) for measuring certain minor and major constituents (free acidity, fatty acids, iodine value, and phenolic compounds) of olive oil. The standard deviations of the NMR method were comparable to those of the conventional methods, except perhaps those of the total hydroxytyrosol and total tyrosol. Linear regression analyses showed strong correlations between NMR and conventional methods for free acidity, total hydroxytyrosol, total tyrosol, total diacylglycerols, (+)-pinoresinol, (+)-1-acetoxypinoresinol, and apigenin; good correlations for linoleic acid, free hydroxytyrosol, and free tyrosol; and weak correlations for oleic acid, linolenic acid, saturated fatty acids, and luteolin. Furthermore, a method comparison study was conducted and the agreement between NMR and conventional methods was evaluated by using the Bland and Altman statistical analysis. The distribution of the data points in the bias plot showed that 96.4% and 100% of the measurements of free acidity and iodine value, respectively, were within the limits of agreement of the two methods. For the remaining constituents of olive oil, the percentage of measurements, located within the limits of agreement, ranged from 94% to 98.5%.
1H-NMR fingerprinting to evaluate the stability of olive oil
Food Control, 2011
a b s t r a c t 1 H-NMR fingerprinting is used to evaluate the stability of olive oil at room temperature while protected from light. Principal component analysis (PCA) of the 1 H-NMR spectral data allows to visualize the evolution of virgin olive oil (VOO) with time. The PCA loadings disclose the chemical compounds responsible for the compositional changes taking place in VOO. None of the 1 H-NMR signals present at time zero disappeared or experienced significant decreases or increases within the 3 years and seven months of the study. However, some small changes in the signals, and the appearance of some low intensity ones, indicate that some oxidative and hydrolytic degradation of the VOO started after one year. The presence of 1 H-NMR signals of hydroperoxides (primary oxidation products) with relative small intensities indicates that the oxidative degradation was taking place at a very low rate and yield. Moreover, the characteristic resonances of aldehydes (main secondary oxidation products) were not detected in the VOO over the studied time period, therefore the secondary oxidation process had not yet occurred. These results confirm the high oxidative stability of VOO at room temperature. On the other hand, slight changes in the 1 H-NMR signal intensity of tryglycerides and sn-1,3-diglycerides indicates that some hydrolytic degradation of the VOO had started.
Journal of the American …, 2000
Analytical measurements and proton nuclear magnetic resonance (1 H NMR) spectra of phenolic extracts were performed on a set of Italian extra-virgin olive oils from different cultivars and geographical locations of Apulia region. Multivariate statistical analysis (principal component analysis, hierarchical clustering analysis, and discriminant analysis) was applied separately to analytical and NMR data. Analytical parameters, in particular fatty acid compositions, permit the discrimination of olive variety, while 1 H NMR data of phenolic extracts permit a classification according to the geographical origin of the samples.
Grasas y Aceites, 2014
The main goal of this study is to rapidly screen olive oil contents by acquiring one dimensional (1D) 1 H NMR spectra of 38 samples from Turkey, The Middle East, and Libya. The quantitative analysis of the 1 H NMR helped in distinguishing the geographical origin of the olive oil samples. The intensity of 1 H NMR variables was submitted to the statistical method, analysis of variance (ANOVA). As a result of combining the NMR data and ANOVA, olive oils were discriminated based on regional origin rather than province. This less time consuming discriminative screening by 1 H NMR does not require any further analysis of the olive oil, including oxidative stability measurements or gas chromatography. The possibility of determining authenticity, even in an olive growing area of a small village was also shown. The two-dimensional (2D) non-invasive 1 H DOSY NMR experiment, known as "NMR chromatography", was used to determine the olive oil sub-fraction.
Foods
This work encompasses the use of 1D multinuclear NMR spectroscopy, namely, 1H NMR and 13C NMR DEPT 45, combined with a multivariate statistical analysis to characterize olive oils produced from nine different varieties: Galega Vulgar, Cobrançosa, Cordovil de Serpa, Blanqueta, Madural, Verdeal Alentejana, Arbequina, Picual and Carrasquenha. Thus, the suitability of an NMR-based spectroscopic tool to discriminate olive oils according to their varietal origin is addressed. The results obtained show that the model based on 13C NMR DEPT 45 data has a stronger performance than the model based on 1H NMR data, proving to be promising in the discrimination of the olive oils under study based on their varietal origin, being particularly relevant for olive oils of the Galega Vulgar variety.
Magnetic Resonance in Chemistry, 2000
1 H NMR spectroscopy provides a possible alternative to conventional chromatographic methods for determining the composition of oils. In this study, various oils from olive, hazelnut and sunflower were analysed by 1 H NMR spectroscopy. Experimental conditions were chosen in order to have a short experimental time. It was demonstrated that multivariate statistical methods, in particular discriminant analysis, applied to selected predominant peaks in the 1 H NMR spectra of oils resulted in a good separation between these three oils of different botanical origin and permitted the detection of their mixtures.