Monovarietal Extra Virgin Olive Oils Research Articles

A comparative study on oxidative and hydrolytic stability of monovarietal extra virgin olive oil in bakery products

An experimental investigation was carried out with the aim to assess the influence of the chemical characteristics of the extra virgin olive oil used in dough formulation of bakery products on the evolution of hydrolytic and oxidative lipid fraction degradation, by means of the determinations of free fatty acids, peroxide value, specific absorption at 232 and 270nm, as well as volatile and polar compounds. At this purpose, three different monovarietal extra virgin olive oils, cultivars Bosana, Coratina and Ogliarola barese (named Ogliarola), having different chemical composition, were tested and used in the taralli production recipes. The obtained data showed that oxidized triacylglycerols significantly increased during storage irrespective of the oils used in dough formulation, whereas peroxide value, K232 and polar compounds significantly increased only in taralli prepared with Bosana oil; all others parameters did not show significant differences. In any case, a different lipid degradation was observed in function of the utilized oils. In particular, when Coratina oil was used, a significant lesser oxidative degradation was observed, probably due to both the higher content of antioxidants (total phenols and carotenoids) and the lower content of substances characterized by pro-oxidant activity (oxidized triacylglycerols and diacylglycerols) than those of Bosana and Ogliarola oils. The results of the volatile compounds confirm the more susceptibility to oxidation of taralli made with Bosana oil. The research assessed the importance of the chemical composition of extra virgin olive oil used in the ingredient formulation of taralli.

Application of a simplified calorimetric assay for the evaluation of extra virgin olive oil quality

Thermal properties of eighteen monovarietal extra virgin olive oils from the Apulia region in Italy were evaluated by means of a modulated adiabatic scanning calorimeter (MASC) and related to their chemical composition (free acidity, UV absorbance, fatty acid composition, polyphenol and o-diphenol content, oxidation status). MASC was used to study oil sample phase transitions in a temperature scanning mode by using a tailor-made time–temperature protocol. Crystallization kinetics and transition enthalpies were found to be significantly correlated to single free fatty acids (palmitic, oleic and linoleic acids) and to unsaturated/saturated fatty acid ratio. The overall crystallization curves were significantly delayed and occurred over longer time ranges as a function of higher peroxide index and linoleic acid content. Significant correlations were observed between melting profiles and single fatty acids, unsaturated/saturated fatty acid ratio and oleic/linoleic acid ratio. No significant correlations were observed between thermal properties and free acidity, linolenic acid, polyphenol and o-diphenol content.Compared with classical differential scanning calorimetry, MASC was simpler to use. The applied time–temperature protocol allowed the characterization of extra virgin olive oils (EVOOs) of different provenience with rapid measurements and giving rise to friendly outcome data. MASC, with its compact and portable equipment, may promote practical applications of calorimetric test along the olive oil supply chain.

Volatile profiles of Italian monovarietal extra virgin olive oils via HS-SPME–GC–MS: Newly identified compounds, flavors molecular markers, and terpenic profile

This study aims to contribute to the knowledge of the commercial, sensory, and analytical characteristics of extra virgin olive oil (EVOO) from Italy (Marche region), renowned since ancient times. Headspace solid-phase micro-extraction (HS-SPME) was applied for the very first time to the sampling of volatile compounds of eleven typical Italian monocultivar EVOOs. Forty-eight compounds were characterised by GC–MS, some of them were only occasionally found in other EVOOs and some other were never detected before in any EVOO. Compounds belonging mainly to alcohols, esters, aldehydes, ketones and hydrocarbons chemical classes characterised the volatile profiles. The main volatile compounds detected in the EVOOs were the C6 compounds derived from polyunsaturated fatty acids, through the lipoxygenase pathway, in different proportion according to the specific cultivar. The results suggest that genetic factors strongly influence volatile formation and terpene hydrocarbons are claimed to be suitable markers of the geographic origin and genotype of the EVOO. Correlations among sensory attributes evaluated by a panel test and the presence of specific volatile compounds were highlighted for the very first time. The significance of the presence of some newly identified volatile compounds was discussed.

Potential of selected Portuguese cultivars for the production of high quality monovarietal virgin olive oil

AbstractThe effect of cultivar and ripeness stage on the potential nutritional value of monovarietal extra virgin olive oils (MEVOOs) obtained from Cordovil, Carrasquinha, Verdeal, and Negrinha do Freixo cultivars was investigated. MEVOOs produced were characterized by high oleic acid (72–83%), tocopherol (182–530 mg/kg), and phenolic compounds (326–1110 mg/kg) content and by a similar polyphenolic profile. 1‐Penten‐3‐one was found to be the compound with the highest contribution for the aroma of the four MEVOO, related to bitter, pungent, and leaf attributes. MEVOO from Verdeal cultivar showed the best performance in terms of the composition: the highest yield of oil, the highest content of oleic acid, high tocopherol, polyphenol and sterol content, and the lowest content of linoleic acid. These characteristics give to these MEVOO not only a great oxidative stability but also interesting properties from the health point of view. MEVOO obtained with fruits at the maturity index of around 4 were in general richer in beneficial minor compounds. MEVOO produced were discriminated by variety and ripeness stage, using a stepwise linear discriminant analysis. This discrimination will in the future enable the prevention of adulteration of these monovarietal olive oils with specific nutritional composition with other olive oils.Practical implications: High‐quality MEVOOs have recently been introduced in the market, which for growers is a practical way to differentiate and increase the commercial value of extra virgin olive oil. The quantification of major and minor olive oil compounds in monovarietal olive oils represents an objective way of predicting the sensory characteristics, stability, and potential health benefits of the oils, as well as preventing their adulteration with other olive oils. This study will help in the selection of olive varieties during the maintenance or development of new olive orchards and also to select optimum harvest period for these varieties, in order to obtain MEVOOs with the maximum quality and health benefits for consumers.

Phenolic composition and antioxidant activity of Southern Italian monovarietal virgin olive oils

AbstractThe phenolic composition and antioxidant activity of several monovarietal extra virgin olive oils used as blenders for the production of Collina di Brindisi protected designation of origin (PDO) oil, produced between December 2008 and January 2009 using two‐phases or three‐phases extraction system, were evaluated and compared with other manufacturer products designated as PDO. Oils were taken from the most representative ones industrial oil mills in the PDO geographical area. The parameters assessed were free acidity, peroxide value, K232 and K270 indices, organoleptic characteristics, total phenolic content (TPC), phenolic profile, and antioxidant activity coefficient (AAC). The phenolic contents and profiles of the monovarietal oils showed remarkable differences with respect to PDO oils. The variables that exerted a major influence on phenols concentration were the maturity degree of olives (December>January), followed by the extraction system (two‐phase>three‐phase), and place of growing. The Pearson r correlation index showed that AAC was positively correlated with TPC, p‐coumarate, and 3,4‐DHPEA‐EA, and negatively correlated with peroxide value.Practical applications: The results provide detailed information about: (i) the phenolic composition and the AAC of several monovarietal extra virgin olive oils used as blenders for the production of a PDO oil; (ii) the impact of genetic variability, place of growing, olive maturity degree, and extraction technology on oil phenol compounds; and (iii) the relationships among each phenolic compound and AAC, and their potential utilization as analytical index of antioxidant activity. It is important to study the phenolic compounds and antioxidant activity of monovarietal extra virgin olive oils used to produce PDO oil and to compare with the relative PDO samples in order to define a possible analytical tool able to verify what is stated in the label for consumer information and protection.

A SNP-based PCR–RFLP capillary electrophoresis analysis for the identification of the varietal origin of olive oils

Authenticity and traceability of high quality monovarietal extra virgin olive oils is a major concern for markets and consumers. Although analytical chemistry techniques are widely used to satisfy these needs recently developed DNA-based methods can serve as complementary approaches. A SNP database comprising 10 Greek olive varieties was constructed and five SNPs, residing in restriction sites, were selected for the development of a PCR-RFLP capillary electrophoresis method to discriminate these varieties using leaf DNA as template. An identification key was constructed indicating that five SNPs were adequate to discriminate nine out of the 10 varieties. As a proof of principle the assay was applied on DNA extracted from five of their corresponding monovarietal olive oils. Three SNPs were able to identify the varietal origin of these olive oils confirming the validity of this approach.

Proton transfer reaction-mass spectrometry volatile organic compound fingerprinting for monovarietal extra virgin olive oil identification

Proton transfer reaction-mass spectrometry (PTR-MS) is a relatively new technique that allows the fast and accurate qualification of the volatile organic compound (VOC) fingerprint. This paper describes the analysis of thirty samples of extra virgin olive oil, of five different varieties of olive fruit (Arbequina, Cornicabra, Frantoio, Hojiblanca, and Picual) by PTR-MS.

A straightforward quantification of triacylglycerols (and fatty acids) in monovarietal extra virgin olive oils by high-temperature GC

The analytical characterization of the triacylglycerol (TAG) profile of samples which include ten Spanish monovarietal extra virgin olive oils (“Hojiblanca”, “Manzanilla”, “Picual”, “Picudo”, “Cornicabra”, “Lechin”, “Verdial”, “Empeltre”, “Blanqueta” and “Arbequina”) is reported. High temperature gas chromatography-(ionic trap)mass spectrometry, HTGC-(IT)MS, was employed for TAG profiling in olive oils. No sample treatment was required. For quantification purposes, a standard calibrant mixture, including all the previously identified TAGs in olive oils, was used. Results showed that triolein (27–50%) and 1,2-olein-3-palmitin (19–38%) were the most abundant TAGs in the analyzed samples, though their relative proportion changed between samples which corresponded to different varieties of olive oils. An estimation of the composition of main fatty acids (FAs) was also enabled in a simple approach from the TAG profiles. This analytical methodology for FA profiling in olive oil was validated by using two external olive oil reference materials. The results were found to constitute an approach, in a fast and easy way without using any derivatization reactions, to a conventional fatty acid methyl ester (FAME) gas chromatography method, when no high analytical performances are mandatory.

Multivariate Analysis of 1H‐NMR Spectra of Genetically Characterized Extra Virgin Olive Oils and Growth Soil Correlations

AbstractMono‐varietal extra virgin olive oils were micro‐extracted from drupes that were selectively collected from 28 trees distributed in five different Southern Italian Apulian areas. Nuclear Magnetic Resonance (NMR) profiles of these oil samples were correlated to the genetic (young green material) and soil (samples collected within the foliage projection) data of the tree of origin. Genetic analysis, performed on the samples using SSRs (Simple Sequence Repeats) by 9 microsatellite loci, confirmed the specific cultivar assignment (among Cima di Mola, Coratina, Ogliarola, and Oliva Rossa cultivars). Chemometric methods applied to 1H‐NMR spectroscopic data were used for cultivar and geographical origin discrimination of the studied extra virgin olive oils. Linear Discriminant Analysis (LDA) afforded a high reliability degree for discriminating cultivars (almost 90% of prediction ability), and a good assigning ability for the geographical origin (Ogliarola and Coratina samples used as subsets). Soil analyses were performed for each tree. Regression analysis was applied to soil composition in order to correlate available nutrients and total metals with the content of fatty acids and minor components present in monovarietal extra virgin olive oils. In the case of oleic and linoleic fatty acids, and for some terpenes, B, Cr, Mn, Zn were found to give significant correlations. Zn and Mn were the most significant trace elements for all the correlations found (p < 0.01). The results obtained (genetic, spectroscopic and soil analyses) are discussed as a multidisciplinary approach for setting up a strategy for a cultivar and/or geographic origin certification committed database construction.

Monovarietal Extra Virgin Olive Oils from the Marche Region, Italy: Analytical and Sensory Characterization

This study aims to contribute to the knowledge of the commercial, sensory, and analytical characteristics of extra virgin olive oil (EVOO) from the Marche region (Italy), renowned since ancient times. The chemical composition of all the most typical monovarietal oils collected in four crop seasons, was studied in relation to the year of harvesting (from 2004–2007) and the genotype. In order to obtain a complete description of oil samples, free acidity, peroxide value, fatty acid composition, ultraviolet indices, carotenoids, chlorophylls, and phenols were determined. The main characteristics of these oils are large total phenol content, low acidity and peroxide values, low oxidative susceptibilities. All the chemical parameters fell within the limits established for the maximum olive oil category. Sensory evaluation showed that the total score of all the monovarietal extra virgin olive oils was always much higher than the 6.5 limit established for the ‘extra-virgin’ category. The overall quality indices support claims of excellence for monovarietal EVOOs from this geographical area. Results from the present study are of key importance for the specific Production Standards a document that contains regulations for supervising the entire olive oil production cycle and a prerequisite for both the European Protected Denomination of Origin (PDO) and Quality granted by the Marche region (QM) labels.

Influence of genetic matrix and crop year on chemical and sensory profiles of Italian monovarietal extra-virgin olive oils

Commercial virgin olive oils belonging to the cultivars (Bosana, Carolea, Coratina, Frantoio, Itrana, Leccino, Moraiolo, Peranzana, Piantone di Mogliano and Ravece) most represented at the Italian National Review of Monovarietal olive oils (Rassegna Nazionale Italiana degli oli Monovarietali) were considered. The evaluation of the influence of the cultivar and of the crop year as well as their interaction on oil composition were statistically analysed by a complete factorial design by principal components analysis and by linear discriminant analysis. In fatty acids composition, the effect of the cultivar and crop year and their interaction were highly significant. The statistical analysis showed that the sensory attributes (olive fruity, grassy, fresh almond, artichoke, tomato, aromatic herbs, bitter and pungent) were strongly influenced by the cultivar. The prevalent effect of the cultivar on the sensory profile was also demonstrated by the low or absent level of significance observed in the crop year. The construction of a databank based on a large number of samples, which is available at URL http://www.olimonovarietali.it, has contributed to the reduction of the variable effects involved in the oil production process. Knowledge of the chemical and sensory profiles of the Italian monovarietal olive oils could start a certification process of these oils, thus giving greater guarantees about their origin.

Separation and Identification of Phenolic Compounds of Extra Virgin Olive Oil from Olea europaea L. by HPLC-DAD-SPE-NMR/MS. Identification of a New Diastereoisomer of the Aldehydic Form of Oleuropein Aglycone

The phenolic fraction of a monovarietal extra virgin olive oil (EVOO) from Olea europaea L. var. Cornezuelo was studied by the hyphenated HPLC-DAD-SPE-NMR/MS techniques. This survey led to the identification of 25 main compounds. One was identified as a new diastereoisomer of the aldehydic form of oleuropein aglycone (AOA) and characterized by 1D and 2D NMR techniques. The relative configuration of this new AOA was determined as 5R*,8S*,9S* on the basis of the results obtained from the combination of NOE experiments and Monte Carlo conformational search calculations. Assuming, as for the described diastereoisomers, that the new AOA comes from the natural oleuropein aglycone (OA), the absolute configuration was proposed as 5S,8R,9R.

Correlation between thermal properties and chemical composition of Italian virgin olive oils

AbstractThirteen monovarietal extra virgin olive oils (EVOos) from two Italian regions were evaluated by means of differential scanning calorimetry (DSC) to study statistical correlations among major and minor chemical components and thermal properties obtained by cooling transitions and their deconvoluted peaks. The application of DSC for the discrimination of EVOos according to the cultivar and geographical origin was also considered. Thermal properties of the cooling transitions (except for the crystallization enthalpy) were almost all influenced by triolein content and fatty acid composition. Thermal properties (area, onset and offset temperatures of transition, transition range, and peak temperature) of the three deconvoluted peaks were found to be significantly correlated not only to major but also to minor components (diacylglycerols, free fatty acids) and oxidative stability indices. The analysis of thermal properties obtained by cooling transition did not lead to sample discrimination according to geographical provenience. However, Ton, Toff, and peak areas of the two deconvoluted transitions that peaked at the lowest temperatures, as well as Toff of deconvoluted peak at the highest temperature, significantly differentiated oil samples according to their geographical origin. These findings may be confirmed by the appliance of multivariate statistical analysis to a larger set of samples to select thermal parameters able to discriminate among EVOos of different geographical provenience.Practical applicationsDSC application exhibits some advantages upon the classical analytical methods as it does not require sample preparation and use of solvents, thus resulting in a reduced environmental impact. The results of this study suggest that DSC can be used to test quality and to determine geographical origin of EVOo.

Chemometrical strategies for feature selection and data compression applied to NIR and MIR spectra of extra virgin olive oils for cultivar identification

The possibility provided by Chemometrics to extract and combine (fusion) information contained in NIR and MIR spectra in order to discriminate monovarietal extra virgin olive oils according to olive cultivar (Casaliva, Leccino, Frantoio) has been investigated. Linear discriminant analysis (LDA) was applied as a classification technique on these multivariate and non-specific spectral data both separately and jointly (NIR and MIR data together). In order to ensure a more appropriate ratio between the number of objects (samples) and number of variables (absorbance at different wavenumbers), LDA was preceded either by feature selection or variable compression. For feature selection, the SELECT algorithm was used while a wavelet transform was applied for data compression. Correct classification rates obtained by cross-validation varied between 60% and 90% depending on the followed procedure. Most accurate results were obtained using the fused NIR and MIR data, with either feature selection or data compression. Chemometrical strategies applied to fused NIR and MIR spectra represent an effective method for classification of extra virgin olive oils on the basis of the olive cultivar.

Thermal Decomposition Study of Monovarietal Extra Virgin Olive Oil by Simultaneous Thermogravimetry/Differential Scanning Calorimetry: Relation with Chemical Composition

Thermal decomposition of 12 monovarietal extra virgin olive oils from different geographical origins (eight from Italy, two from Spain, and the others from Tunisia) was evaluated by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC) analyses. All extra virgin olive oils showed a complex multistep decomposition pattern with the first step that exhibited a quite different profile among samples. Thermal properties of the two peaks obtained by the deconvolution of the first step of decomposition by DSC were related to the chemical composition of the samples (triacylglycerols, fatty acids, total phenols and antioxidant activity). Onset temperatures of the thermal decomposition transition and T(p) values of both deconvoluted peaks as well as the sum of enthalpy were found to exhibit statistically significant correlations with chemical components of the samples, in particular palmitic and oleic acids and related triacylglycerols. Activation energy values of the second deconvoluted peak obtained by the application of kinetic procedure to the first step of decomposition were also found to be highly statistically correlated to the chemical composition, and a stability scale among samples was proposed on the basis of its values.

Distribution of simple phenols, phenolic acids and flavonoids in Turkish monovarietal extra virgin olive oils for two harvest years

Monovarietal extra virgin olive oils extracted from six dominant and economically important Turkish olive cultivars (memecik, erkence, domat, nizip-yaglik, gemlik, ayvalik) were examined for their simple phenolics, phenolic acids and flavonoid compounds over 2005 and 2006 harvest years. Total phenol contents, oxidative stabilities and chromatic ordinates as colour parameters were also measured. The most typical phenolic compounds that were identified in both years are hydroxytyrosol, tyrosol, vanillic acid, p-coumaric acid, cinnamic acid, luteolin, and apigenin. Multivariate data were analysed by principal component and partial least square-discriminant analyses. It was observed that phenolic profiles of olive oils depended highly on harvest season. In addition, oils of different olive cultivars have different distribution of phenols. No significant correlation was observed between oxidative stability and phenolic compounds. Increase in peroxide value over an accelerated oxidation period of 11 days showed weak correlations with total phenol content, vanillin, syringic acid and colour parameter a ∗, as 0.56, 0.55, −0.42, and 0.51, respectively, in terms of correlation coefficient r.

A procedure for olive oil traceability and authenticity: DNA extraction, multiplex PCR and LDR–universal array analysis

Traceability of olive oils is relevant not only in assessing their origin, but also in protecting against frauds. Here, we present an improvement of the assay previously developed for the genotyping of forty-nine frequently grown Mediterranean olive cultivars by ligation detection reaction (LDR)/universal array (UA), refining the entire procedure in order to address DNA extracted from monovarietal olive oils. Firstly, a simple and robust protocol to extract amplifiable DNA from olive oil was developed. Then, the SNP-containing DNA sequences were simultaneous amplified by multiplex PCR and used on a LDR-UA platform, which gave precise and accurate genotype results. Thirteen out of the seventeen investigated SNPs were amplifiable in multiplex PCR, and were sufficient to unequivocally discriminate the forty-nine cultivars. The availability of this semi-automated SNP genotyping assay should help food testing laboratories to verify the origin and authenticity of monovarietal extra-virgin olive oils.

Monovarietal Extra Virgin Olive Oils. Correlation between Thermal Properties and Chemical Composition: Heating Thermograms

Extra virgin olive oils from drupes of three Sicilian varieties (Biancolilla, Cerasuola, and Nocellara del Belice) collected at three different harvesting periods were analyzed upon heating by means of DSC, and thermal properties were related to the chemical composition of the samples. All thermograms exhibited multiple transitions with a minor exothermic peak, followed by a major endothermic event. Cerasuola samples showed higher overall enthalpy and narrower range of transition at all harvesting periods, as compared to the other oils. A more ordered crystal structure originating from a more uniform chemical composition, with higher triolein content, in Cerasuola may be hypothesized. At different harvesting periods, thermal transitions started at lower temperatures and developed over a narrower range in all cultivars, probably due to the insertion of molecules derived from triacylglycerol lysis (diacylglycerols and free fatty acids) and lipid oxidation products into the triacylglycerol crystal lattice. All heating thermograms were deconvoluted into one exothermic and five endothermic constituent peaks, and the effect of chemical components on thermal properties of the peaks was evaluated. DSC application upon heating appears to be very promising in discriminating among oil samples from olives of different cultivars and/or harvesting periods.

Characterisation and Classification of Italian Virgin Olive Oils by Near- and Mid-Infrared Spectroscopy

Virgin olive oil quality is the result of complex interactions between olive variety, environment and cultivar practice. Evaluation of its quality is based on chemical and sensory analyses (ECC Regulation) that are time-consuming, expensive and destructive of the sample. Spectroscopic techniques present significant advantages in terms of speed and cost of analysis per sample. Italian extra virgin olive oils from Lombardy, Tuscany and Calabria were analysed by conventional analytical and spectroscopic methods. The sample set was composed of 60 single-cultivar (Casaliva, Leccino and Frantoio) extra virgin olive oils (monovarietal extra virgin olive oils) and 59 extra virgin olive oils produced from a mixture of cultivars from each geographical area (industrial extra virgin olive oils). Free acid content, peroxide value and spectrophotometric indices ( K232, K270 and Δ K) were measured. Olive oils were also analysed by near infrared (NIR) and mid-infrared (MIR) spectroscopy in transmission and attenuated total reflectance, respectively, to classify oils on the basis of their geographical origin. Principal component analysis was applied both to chemical and spectral data as an exploratory technique. Classification methods studied were linear discriminant analysis, partial least squares discriminant analysis and soft independent modelling of class analogy (SIMCA). Both FT-NIR and FT-IR allowed sample classification of oils on the basis of geographical origin. NIR spectroscopy was able to classify better the industrial extra virgin olive oils producing a correct classification of about 90% of the samples, while the MIR technique was able to classify both monovarietal and industrial olive oils, allowing a higher correct classification of samples (>95%). SIMCA applied to MIR spectra classified about 70% of samples correctly on the basis of geographical origin.

Monovarietal Extra Virgin Olive Oils: Correlation Between Thermal Properties and Chemical Composition

Thermal properties of monovarietal extra virgin olive oils were evaluated by means of differential scanning calorimetry (upon cooling) and related to their chemical composition (triacylglycerols, diacylglycerols, total and free fatty acids, oxidation status). The overall crystallization enthalpy did not significantly differ among samples and did not account for the differences observed in chemical compositions. On the contrary, a higher degree of unsaturation in the lipid profile induced a shift of the crystallization onset towards lower temperatures and narrowing of the crystallization temperature range. The presence of triacylglycerol lysis and lipid oxidation products shifted the crystallization towards higher temperatures and the phase transition developed over a larger temperature range. Differential scanning calorimetry thermograms were deconvoluted into three constituent exothermic peaks for all samples. The area of the two lower-temperature exotherms was found to be statistically correlated with the amount of triunsaturated and monosaturated triacylglycerols present in the oil. Thermal properties of extra virgin olive oil were found to be affected by oil chemical composition.