Volatile organic compounds strongly contribute to both the positive and negative sensory attributes of virgin olive oil, and more and more studies have been published in recent years focusing on ...several aspects regarding these molecules. This Review is aimed at giving an overview on the state of the art about the virgin olive oil volatile compounds. Particular emphasis was given to the composition of the volatile fraction, the analytical issues and approaches for analysis, the sensory characteristics and interaction with phenolic compounds, and the approaches for supporting the Panel Test in virgin olive oil classification and in authentication of the botanical and geographic origin based on volatile compounds. A pair of detailed tables with a total of approximately 700 volatiles identified or tentatively identified to date and tables dealing with analytical procedures, sensory characteristics of volatiles, and specific chemometric approaches for quality assessment are also provided.
This study examines the price relationships between the three major EU olive oil markets; Spain, Italy and Greece. The empirical analysis utilises a series of linear and non-linear econometric ...techniques to explore long and short run relations examining market integration as well as the pattern of price transmission. The study utilises monthly wholesale data for virgin olive oil for the three countries, covering the period January 2000 to April 2022. Results from the Diks and Panchenko nonlinear causality test suggest Spain to be the central market and stable long-run relations are revealed between the examined price pairs through the non-linear Momentum Threshold Cointegration model, with the strongest relation being identified between Italy and Greece. Regarding the pattern of price transmission, it is found to be asymmetric for the pairs Spain-Greece and Spain-Italy, whereas for price pair Italy-Greece symmetry is confirmed, and the Law of One Price holds in its strong version. This suggests that while the markets are integrated, the EU olive oil market is characterised by inefficiencies indicating the need for further reforms.
Due to the health benefits of extra virgin olive oil (EVOO) and its increasing consumption patterns, adulteration of these oils using lower grade olive oils like virgin olive oil (VOO) and then later ...sold as EVOO to unsuspecting consumers has become a concern in the industry. There is a need for quick, reliable and inexpensive detection techniques to unmask such vice in order to realize its benefits. In this study, adulteration of EVOO is made using VOO at different proportions; their Excitation Emission Matrices (EEM) were examined using Front-face fluorescence spectroscopy and their corresponding fluorescence images captured using 365 nm ultra-violet (UV) LED for analysis. Specific regions for both the EEM and imaging were explored using Support Vector Machine (SVM) classification analysis and their sensitivities evaluated using Partial Least Squares Regression (PLSR) analysis. It was found that EEM excitation 230–500 and emission 260–620 nm could easily discriminate between different samples as EVOO mixed (at different ratios) and VOO. The significant fluorescence peaks for the discrimination forms a combination of Tocopherols, Tocotrienols, Phenolic compounds, Oxidation products and Vitamin E. The results show that Front-face fluorescence spectroscopy and UV-induced fluorescence imaging can potentially discriminate between pure EVOO and adulterated olive oils.
•Fluorescence EEMs for olive oils were measured.•Imaging system was established according to the EEMs to acquire images.•PCA and SVM classification was carried out.•PLSR model for ΔK and FFA was established.•EEM and image features verified potential to discriminate pure EVOO and adulterated ones.
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•A sono-exchanger has been designed.•A sono-exchanger has been prototyped and tested.•High power ultrasounds enhance virgin olive oil quality.•High power ultrasounds enhance virgin ...olive sensory evaluation.•High power ultrasounds inhibit the olive polyphenoloxidase enzyme.
The aim of the virgin olive oil extraction process is mainly to obtain the best quality oil from fruits, by only applying mechanical actions while guaranteeing the highest overall efficiency. Currently, the mechanical methods used to extract virgin oils from olives are basically of two types: the discontinuous system (obsolete) and the continuous one. Anyway the system defined as “continuous” is composed of several steps which are not all completely continuous, due to the presence of the malaxer, a device that works in batch. The aim of the paper was to design, realize and test the first full scale sono-exchanger for the virgin olive oil industry, to be placed immediately after the crusher and before the malaxer. The innovative device is mainly composed of a triple concentric pipe heat exchanger combined with three ultrasound probes. This mechanical solution allows both the cell walls (which release the oil droplets) along with the minor compounds to be destroyed more effectively and the heat exchange between the olive paste and the process water to be accelerated. This strategy represents the first step towards the transformation of the malaxing step from a batch operation into a real continuous process, thus improving the working capacity of the industrial plants. Considering the heterogeneity of the olive paste, which is composed of different tissues, the design of the sono-exchanger required a thorough fluid dynamic analysis. The thermal effects of the sono-exchanger were monitored by measuring the temperature of the product at the inlet and the outlet of the device; in addition, the measurement of the pigments concentration in the product allowed monitoring the mechanical effects of the sono-exchanger. The effects of the innovative process were also evaluated in terms of extra virgin olive oil yields and quality, evaluating the main legal parameters, the polyphenol and tocopherol content. Moreover, the activity of the polyphenol oxidase enzyme in the olive paste was measured.
The aim of this study was to verify the effectiveness of an active biodegradable film on the maintenance of extra‐virgin olive oil (EVOO) quality attributes. Level of peroxides, acidity, K232, color, ...chlorophylls, and carotenoids were determined as parameters to verify the oil quality over storage period. Maltodextrin was used to encapsulate anthocyanins and was the major component in the films, which were used as pouches to pack the oil. The samples were stored at 40°C, exposed to fluorescent light, and monitored during 12 days. The film successfully maintained the quality of EVOO under the limits established by Codex Alimentarius for over 8 days (13.6 meq O2/kg of peroxides at the 8th day), while the oil packed in polypropylene pouches was degraded before the 4th day of storage (326.5 meq O2/kg). Therefore, the results demonstrated the effectiveness of the film on maintaining the quality of EVOO and its promising application as active packaging.
Practical application
Extra‐virgin olive oil (EVOO) is an oxidation‐sensitive product and has been shown to quickly deteriorate when stored under less than ideal conditions. The study brings a new packaging possibility to the commercialization of EVOO with longer shelf‐life. The storage of extra‐virgin olive oil in biodegradable pouches produced with anthocyanins could preserve EVOO from oxidation and consequently extent its shelf‐life. The study proves the efficacy of an active biodegradable packaging on maintaining quality attributes of EVOO. The commercialization of EVOO in active biodegradable pouches could be an eco‐friendly and sustainable way to bring health and practicality to consumers.
► High power ultrasounds enhance virgin olive oil quality. ► High power ultrasounds improve oil yields reducing the process time. ► Ultrasound scaling up projects are proposed for industrial VOO ...plants.
Malaxation has been recognized as one of the most critical points in the mechanical extraction process for virgin olive oil (VOO). It is a low and continuous kneading of olive paste at a carefully monitored temperature. Through this essential technological operation the small droplets of the oil formed during the milling merge into large drops that can be easily separated with a decanter centrifuge. During this technological phase, a complex and necessary bioprocess takes place in order to determine the quality and composition of the final product. The malaxer is a heat exchanger characterized by a low overall heat transfer coefficient because the ratio of surface area to volume is disadvantageous, so it is important to find an innovative technology to improve heat-exchange. As matter of fact, the malaxing step is the only discontinuous phase in a continuous extraction process. In the next future, the essential challenge of VOO industrial plant manufacturing sector is to design and build advanced machines in order to transform the discontinuous malaxing step in a continuous phase and improve the working capacity of the industrial plants. In order to reduce the malaxing time enhancing the quality of the product, two ultrasound-assisted virgin olive oil extraction processes were tested against the traditional method. The sonication treatment was applied on olives submerged in a water bath (before the crushing) and on olive paste (after the crushing). The ultrasound technology provides a reduction of the malaxing duration improving VOO yields and its minor compounds content. Better extractibility and higher minor compounds contents were obtained by sonicating the olives submerged in a water bath than olive paste. After experimental trials the results were employed to suggest innovative scaling up solutions of the process and new applications of ultrasounds in the VOO industry.
Fourier-transform infrared spectroscopy (FTIR), followed by multivariate treatment of the spectral data, was used to classify vegetable oils according to their botanical origin, and also to establish ...the composition of binary mixtures of extra virgin olive oil (EVOO) with other low cost edible oils. Oil samples corresponding to five different botanical origins (EVOO, sunflower, corn, soybean and hazelnut) were used. The wavelength scale of the FTIR spectra of the oils was divided in 26 regions. The normalized absorbance peak areas within these regions were used as predictors. Classification of the oil samples according to their botanical origin was achieved by linear discriminant analysis (LDA). An excellent resolution among all categories was achieved using an LDA model constructed with eight predictors. In addition, multiple linear regression models were used to predict the composition of binary mixtures of EVOO with sunflower, corn, soybean and hazelnut oils. For all the binary mixtures, models capable of detecting a low cost oil content in EVOO as low as 5% were obtained.
Fatty acid composition as an indicator of purity suggests that linolenic acid content could be used as a parameter for the detection of extra/virgin olive oil fraud with 5% of soybean oil. The ...adulteration could also be detected by the increase of the trans-fatty acid contents with 3% of soybean oil, 2% of corn oil, and 4% of sunflower oil. The use of the ΔECN42 proved to be effective in Chemlali extra-virgin olive oil adulteration even at low levels: 1% of sunflower oil, 3% of soybean oil, and 3% of corn oil. The sterol profile is almost decisive in clarifying the adulteration of olive oils with other cheaper ones: 1% of sunflower oil could be detected by the increase of Δ7-stigmastenol and 4% of corn oil by the increase of campesterol. Linear discriminant analysis could represent a powerful tool for faster and cheaper evaluation of extra-virgin olive oil adulteration.
•Coratina and Bosana VOOs have high phenolic content along the whole harvest period.•Tonda di Cagliari and Semidana VOOs have high nutraceutical content at first harvest.•Oleacein and oleocanthal ...increase during ripening only in Coratina variety.•OPLS shows with high accuracy changes in oleacein and ligstroside aglycon content.
Fatty acids, phenolic compounds, and tocopherols of Coratina, Bosana, Semidana, and Tonda di Cagliari virgin olive oils, were measured over a 45-day harvest period. Phenolic composition was the primary factor distinguishing Bosana, Tonda di Cagliari, and Semidana, whereas fatty acids differentiated Coratina and the other cultivars. Harvest period principally influenced oleacein, oleocanthal, oleuropein and ligstroside aglycones, and flavonoids. High phenolic content was observed for Coratina (1039–688 mg/kg) and Bosana (788–592 mg/kg). A drastic decrease in phenolic content was observed in Semidana (529–134 mg/kg) and Tonda di Cagliari (507–142 mg/kg) during the harvest period. These two cultivars also had low MUFA/PUFA (6.0–4.0 and 4.9–3.2 respectively), suggesting that these varieties should be harvested earlier in the season. These results provide information to producers for improved management of the harvesting process, which is strongly affected by varietal factors.
In this preliminary study, ultra-high-pressure liquid chromatography (UHPLC) coupled to quadrupole-time-of-flight mass spectrometry (QTOF) metabolomics followed by multivariate statistics was applied ...to discriminate nine extra-virgin olive oil (EVOO) cultivars according to their phenolic and sterolic fingerprints. The same approach was then used to discriminate EVOO samples from different geographical origins, namely six blends representative of the main growing regions in Italy (i.e., Sicily, Puglia, Umbria, Liguria, Lombardy and Tuscany).
This approach allowed to putatively identify >1000 compounds, considering both polyphenols and sterols. The unsupervised hierarchical cluster analysis (HCA) and the orthogonal projections to latent structures discriminant analysis (OPLS-DA) discriminated EVOO samples according to both cultivar and geographical origin. In particular, flavonoids (i.e., anthocyanins and flavonols), hydroxycinnamic acids and cholesterol derivatives were found to be the most representative classes of compounds discriminating EVOO samples according to the two parameters (cultivar or geographical origin) selected. However, the following Venn analysis allowed to point out the discriminant markers being exclusive for cultivar or origin discrimination. In this regard, only the 9.6% of phenolics and 13.6% of sterols were in common, thus indicating that several of these discriminant compounds were exclusive of a single condition. Indeed, considering that most of the commercial EVOOs are blended, the contribution of both the cultivars used and the geographical origin must be taken into account.
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•Sterolic and phenolic profiles in EVOO accounted for >1000 compounds.•The chemical fingerprints of each EVOO cultivar analyzed showed differences.•Multivariate statistics discriminated EVOO according to geographical origin.•Flavonoids, hydroxycinnamics and cholesterol derivatives were the best markers.
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