Olive Oil Authenticity Research Articles

1H and13C NMR of virgin olive oil. An overview

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 esterified or refined 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. © 1997 John Wiley & Sons, Ltd.

Authentication of European Virgin Olive Oils by Their Chemical Compounds, Sensory Attributes, and Consumers' Attitudes

Twenty-four samples of four European virgin olive oil varietiesArbequina, Coratina, Koroneiki, and Picual, cultivated in Greece, Italy, and Spainhave been analyzed from their chemical composition (either nonvolatile compounds (31)fatty acids, sterols, alcohols, and methylsterolsor volatile ones (65)aldehydes, alcohols, furans, hydrocarbons, acids, ketones, and esters), sensory attributes (103), and consumers' attitudes, the latter in terms of their overall acceptability and sensory comments from their acceptability trials. The paper describes and explains the most remarkable of these parameters characterizing the virgin olive oil varieties, which can be useful in virgin olive oil authentication. The agreement between the concentration of chemical compounds and sensory attributes is explained wherever possible. Keywords: Virgin olive oil; authenticity; flavor; analysis; consumers' attitudes

A high‐field1H nuclear magnetic resonance study of the minor components in virgin olive oils

AbstractHigh‐field (600 MHz) nuclear magnetic resonance (NMR) spectroscopy was applied to the direct analysis of virgin olive oil. Minor components were studied to assess oil quality and genuineness. Unsaturated and saturated aldehyde resonances, as well as those related to other volatile compounds, were identified in the low‐field region of the spectrum by two‐dimensional techniques. Unsaturated aldehydes can be related to the sensory quality of oils. Other unidentified peaks are due to volatile components, because they disappear after nitrogen fluxing. The statistical analysis performed on the intensity of these peaks in several oil samples, obtained from different olive varieties, allows clustering and identification of oils arising from the same olive variety. Diacylglycerols, linolenic acid, other volatile components, water, acetic acid, phenols, and sterols can be detected simulteneously, suggesting a useful application of high‐field NMR in the authentication and quality assessment of virgin olive oil.

A fuzzy filter for removing interferences among membership grade functions An application to pre-treatment of data in olive oil authentication

A fuzzy filter has been defined to partially eliminate interference between membership grade functions for the cases of absence and presence of uncertainty in input data. A functional study allowed us to analyse the effects on the qualified response of parameters involved in its definition, and hence choose the optimum values for them. Two applications concerning the authentication and sensory evaluation of olive oil are presented. Furthermore, the study reveals that its implementation in more general and sophisticated techniques is a straightforward matter, it being very appropriate for the pre-processing of fuzzy data.

Detection of olive oil adulteration by measuring its authenticity factor using reversed-phase high-performance liquid chromatography

Addition of as little as 1% of linoleic-rich vegetable oils to olive oil can be detected easily and quantitatively by reversed-phase high-performance liquid chromatography on an octyl-bonded silica stationary phase (Supelcosil-LC 8). The mobile phase was acetone-acetonitrile (70:30, v/v), used isocratically. The chromatogram of pure olive oil was compared with those of mixtures of soybean, sunflower and corn oils with olive oil. The results indicate the possibility of the detection of adulteration by less than 1% of linoleic-rich vegetable oils in olive oil qualitatively and quantitatively in less than 15 min. An olive oil authenticity factor was established as a rapid indicator of adulteration and a simple equation for determining the extent of adulteration was derived.

Detailed and exhaustive study of the authentication of European virgin olive oils by SEXIA expert system

The authentication of extra virgin olive oils from different regions of Spain, Italy and Portugal, by means of their fatty acids, alcohols, sterols, methyl sterols and hydrocarbons content, has been investigated. Multivariate statistical methods and Evidence's Theory were applied. The comparative study shows greater predictive ability using this theory than the traditional statistical methods or expert systems that do not implement the possibility theory. A detailed and exhaustive study of Italian (Tuscany and Basilicata), Portuguese and Spanish virgin olive oils has been made. Geographically coloured maps of the studied regions are shown to strengthen the numerical results.

Authentication of virgin olive oils using principal component analysis of triglyceride and fatty acid profiles: Part 2—Detection of adulteration with other vegetable oils

Principal Component Analysis of triglyceride and fatty acid profiles has been reported as a method for the characterisation of virgin olive oils, and this approach is now extended to study adulteration of the same oils. The effect of incorporating 10 or 20% w/w of maize, cottonseed, sunflower, soyabean or rapeseed oil in olive oil on both the triglyceride and fatty acid compositions is studied. At the 20% level of incorporation PCA was able to show clearly the presence of a foreign oil, the distinction being less marked at the 10% level. The triglyceride profiles proved to be more discriminating than those of the fatty acids.

Authentication of virgin olive oils using principal component analysis of triglyceride and fatty acid profiles: Part 1—Classification of greek olive oils

Forty-five authentic samples of Greek virgin olive oils, collected from various locations over two seasons, were analysed for fatty acid composition by GLC and for triglyceride composition by HPLC. The data obtained were analysed statistically using Principal Component Analysis. The olive oils could be separated into distinct groups using either the fatty acid or triglyceride data, although the latter provided a higher level of discrimination. It was concluded that the method showed considerable potential for both the characterisation of olive oils and the detection of adulteration.

Qualitative and quantitative markers to identify the quality and adulteration of olive oil with rapeseed oil

The objective of this study was to develop a rapid and convenient chromatographic method for authenticity control of vegetable oils using the total sterol profile determined by gas-chromatography (GC) with flame ionization detector (FID). Two pure oils, rapeseed and olive oil, processed by minimal technologies (cold pressing) in Romania and an adulterated olive oil with 40 % of rapeseed oil were used as sample matrices in the method development. The rapeseed oil can be identified by the presence of brassicasterol (see peak number 2 in Figure 2.) which is characteristic mainly for this oil. In olive oil, this sterol is absent. The concentrations of b-sitosterol, campesterol and brassicasterol as well their ratios can identify the adulteration of virgine olive oil with rapeseed oil. High ratios b-sitosterol/ campesterol are specific to virgin olive oil (~ 27.5) while these ratios are low (~2) for rapeseed oil or adulterated olive oil. Also the ratio campesterol / brassicasterol can indicate the adulteration. This ratio is low (~2) for rapeseed oil and higher (~ 4.8) in extra virgin olive oil. Adulteration of olive oil with rapeseed oil determine the decrease of this ratio. In this work we report three ways to identify the quality and authenticity of olive oil. We found as well markers which indicate if the olive oil was adulterated with rapeseed oil.