Virgin Olive Oil Quality Research Articles

Phenolic acid content and sensory properties of two Spanish monovarietal virgin olive oils

AbstractIn recent years, phenolic acids have received considerable attention as they are essential to olive oil quality and nutritional properties. This study aims to validate a rapid and sensitive method based on ultra‐performance liquid chromatography/time‐of‐flight mass spectrometry (UPLC–TOF‐MS) for analyzing the phenolic acid content of olive oil and assessing its impact on virgin olive oil (VOO) sensory attributes. Once this method was validated, we used it to evaluate the phenolic acid composition of several Spanish monovarietal virgin olive oils in relation to nine different olive ripening stages. The results obtained confirm that the methodology developed in this study is valid for extracting and analyzing phenolic acids from VOO. The phenolic acid content of the virgin olive oils sampled was proven to be influenced by the type of cultivar and olive harvest date. Therefore, phenolic acids might be used as potential markers for olive oil cultivar or ripening stage. Finally, the data obtained indicate that the sensory properties of VOO may be differently affected by its phenolic acid content depending on the type of cultivar.Practical applications: The method validated in the present study – based on UPLC‐TOF‐MS – allows experts to assess the phenolic acid content of different VOO cultivars (varieties). This application will probably be very useful to the olive oil industry. The reason is that our study revealed that phenolic acids have an impact on the sensory quality of VOO, which is essential to consumer preferences and choice. In addition, there are phenolic acids that are only found in a particular variety of olive oil obtained from fruits at a specific ripening stage. Consequently, phenolic acids could be used as potential markers for olive oil variety and harvest time.

Olive oil quality and ripening in super‐high‐density Arbequina orchard

The aim of this work was to evaluate the evolution of the quality of extra virgin olive oil obtained from a super-high-density Arbequina orchard, under a drip irrigation system, throughout the ripening process. For this objective, physicochemical, nutritional and sensory parameters were studied. In addition, the oxidative stability, pigment content and colour evolution of olive oil were analysed during the ripening process. Free acidity increased slightly throughout the ripening process, while peroxide value and extinction coefficient decreased. Total phenol content and oxidative stability showed a similar trend, increasing at the beginning of ripening up to a maximum and thereafter decreasing. α-Tocopherol and pigment contents decreased with ripening, leading to changes in colour coordinates. Sensory parameters were correlated with total phenol content, following a similar trend throughout the maturation process. By sampling and monitoring the ripeness index weekly, it would be possible to determine an optimal harvesting time for olives according to the industrial yield and the physicochemical, nutritional and sensory properties of the olive oil.

Relevance of minor components stability in commercial olive oil quality during the market period

AbstractThe aim of this research was to study the relevance of the stability of minor components in commercial Spanish extra virgin and olive oil (OO) categories, particularly with respect to the individual phenolic compounds, tocopherols (vitamin E) and volatile compounds, during the market period (12 months). The study was carried out classifying several commercial olive oils (n = 39) according to their content in phenolic compounds into three different groups: extra virgin olive oils with high (>290 mg/kg; HP‐VOO) and low (<210 mg/kg; LP‐VOO) phenolic level and OO, due to the impact of biophenols on oxidative stability, sensory properties and nutritional aspects. After a market period of 1 year, the α‐tocopherol content fell significantly (25–30% of its initial content) in the commercial oils. While the decrease in total phenolics and o‐diphenols was not statistically significant, a relevant increase (33% on average) in simple phenolics (hytroxytyrosol and tyrosol) was observed in all the studied samples, suggesting its use as freshness or ageing marker. Throughout the market period, a low oxidation rate and therefore a high stability of the products was observed. Moreover, the results found in the study suggest that a higher market price OO is apparently related to better quality and process control, giving a superior final product in terms of its content of minor components related to organoleptic properties.Practical applications: The quality of virgin olive oil – mainly its sensory characteristics and nutritional value – is directly related to its content in minor components, in particular phenolics and volatile compounds, and therefore to their stability during the market period. Nevertheless, this information is not available to consumers. As a consequence, it is very important for both producers and consumers to clarify and establish the real relevance of the stability of minor components in commercial olive oil categories during their shelf‐life: how long they will keep their stability, organoleptic and nutritional characteristics. This information would highlight the individual quality properties of a specific oil product, beyond the sometimes misleading commercial category.

Fourier transform mid‐infrared spectroscopy evaluation of early stages of virgin olive oil autoxidation

AbstractThe applicability of FT‐MIR/ATR spectroscopy (4000–400 cm−1) for the evaluation of early stages of autoxidation was examined for extra virgin olive oil samples (EVOO), which even after 12‐month storage (dark, 23 ± 3°C) satisfied official limits for acidity, peroxide, K232 and K270 values. Changes in intensity values at 3470 cm−1 (hydroperoxide formation) and in values of various intensity ratios, namely A3006/2924, A3006/2853, A3006/1746, A3006/1465, A3006/1163, A1118/1097, A2853/1746, A2853/1417, A2853/1163, A2853/1118, A2853/1097, and A2853/723 (relevant to the degree of oil unsaturation) did not offer more information than the physicochemical criteria when examined one by one. Principal component – discriminant analysis of intensity values at 2924, 2853, 1746, 1465, 1163, 1118, 1097, and 723 cm−1 led to a 100, 91, and 54.5% correct classification for the 12, 6, and 0 months stored ones, respectively. Improvement in correct classification of the latter (73–91%) was obtained when the second derivatives of various spectral ranges were treated by the same statistical approach. Frequencies assigned to stretching and/or bending of CO and CH2 groups (1020–1260 cm−1) produced the best discrimination among samples. Findings are discussed with reference to literature reports about FT‐MIR applicability under various oxidation conditions of virgin olive oil (VOO). A systematic inter‐laboratory study is suggested in order FT‐MIR/ATR to be used as a robust tool in VOO quality control.Practical applications: There is an increasing awareness among consumers and olive oil producers and distributors about virgin olive oil freshness and discussions are on the way for updating of the relevant EU regulations on its quality characteristics. Modernization of methods of analysis and introduction of additional criteria can be achieved by the employment of powerful techniques that can provide solid, multiple type of information with little sample manipulation. FT‐MIR/ATR requires no sample preparation, the spectra are related to all chemical components of the lipid matrix and are recorded over a broad region (4000–400 cm−1) in few minutes. Chemometric analysis of the numerous peaks extracts all of the valuable information that can enhance claims or disputes about the oxidative status of a virgin olive oil (e.g., freshness or loss of freshness). Moreover, FT‐MIR apparatus has multiple uses in the oil industry (authenticity, origin) so that an investment on such a green technique is advisable.

Effect of different irrigation regimes on the quality attributes of monovarietal virgin olive oil from cv. “Cobrançosa”

The aim of this study was to assess the effect of different irrigation strategies in virgin olive oil (VOO) composition and quality of cv. Cobrancosa, integrated in a protected denomination of origin of “Azeite de Tras-os-Montes” in the Northeast of Portugal. Three irrigation treatments were applied: T2-full irrigation that received a seasonal water equivalent to 100% of estimated crop evapotranspiration (ET c ), T1-continuous deficit irrigation (30% ET c ) and T0- rainfed treatment. Data were collected from two consecutive crop years (2005-2006). Irrigation regimes had a minor effect on standard quality indices (free fatty acids, peroxide value, K 232 and K 270 ) of VOO and in fatty acid composition. Total polyphenols decreased up to treatment T2, and were strongly related to the water stress integral, suggesting that the effect of irrigation on this variable occurs along the crop season and not just during the oil accumulation phase. A strategy of continuous deficit irrigation with only 30% of maximum ETc may have an advantageous effect, as it increased oil yield to more than double that of rainfed conditions while VOO quality was similar.

Sensory analysis and volatile compounds of olive oil (cv. Cobrançosa) from different irrigation regimes

The aim of this study was to assess the effect of different irrigation strategies on the sensory quality of virgin olive oil (VOO) from the cv. “cobrancosa” integrated into a protected denomination of origin of “Azeite de Tras-os-Montes” in the Northeast of Portugal. Three irrigation treatments were applied: (T2)-full irrigation, which received a seasonal water equivalent of 100% of the estimated crop evapotranspiration (ET c ), (T1)-continuous deficit irrigation (30% ET c ) and (T0)- rainfed treatment. Data were collected from two consecutive crop years (2005-2006). Olive oil samples were analyzed for volatiles by GC-MS and the results compared with sensory evaluation data. Total volatile compounds tended to decrease with the amount of water applied. The characteristics pungent and bitter were more pronounced in olive oils from T0 and T1, which had higher polyphenolic concentrations, with a strong positive relationship with this variable and the bitter attribute. The Principal Components Analysis clearly separates the three olive oils from 2005, the driest year, and aggregates into a single group the three samples from 2006, suggesting no effect of irrigation on volatile compounds in years with a rainy spring and a marked effect in years with severe drought, suggesting that the effect of the trees’ water status on these variables occurs throughout the crop season and not just during the oil accumulation phase. In general, olive oil from the cv. Cobrancosa is more bitter than pungent and has a typical nutty sensory attribute shown by a strong positive relationship between benzaldehyde and the sensory notes of almonds and nuts.

An oxygen monitoring and control system inside a malaxation machine to improve extra virgin olive oil quality

In recent years, oxygen content regulation during malaxation has been noted as a process parameter. The aim of this study was to identify the optimal time during the malaxation process of the olives of the Sicilian cultivar Nocellara del Belice when the presence of oxygen in the machine headspace activates the enzyme complex in favour of the volatile compounds, without compromising the phenolic composition. During the malaxation process, the atmosphere inside the malaxation machine was modified by blowing pure oxygen from cylinders at specific stages of the process (i.e., 5, 15, 25, and 35 min after the start of malaxation), using a system that allows the automatic and continuous maintenance of a known amount of oxygen in the headspace at a given moment during the entire process of malaxation. The results showed that under the experimental boundary conditions, malaxation carried out in an oxygen free atmosphere for the first 25 min followed by the presence of oxygen until the end of the process could enhance volatile compounds in extra virgin olive oils, without compromising the phenolic composition.

Evaluation of minor components, sensory characteristics and quality of virgin olive oil by near infrared (NIR) spectroscopy

Chemometric analyses of NIR spectral data (12,500–4000cm−1) combined with analytical and sensory parameters measured in monovarietal Cornicabra virgin olive oils (VOOs) (n=97) produced in the PDO (Protected Denomination of Origin) “Montes de Toledo” geographic area were used to generate calibration and validation models in order to be able to predict the minor composition of VOO, in particular its phenolic and volatile compounds as well as its organoleptic attributes, and thereby the global quality of the product. Acceptable multivariate algorithms were obtained for VOOs' degree of unsaturation (fatty acid profile) (r=0.84–0.96), several minor components – in particular hydroxytyrosol derivatives (r=0.86–0.88) and C6 alcohols (r=0.69–0.80) – as well as for positive sensory attributes — ‘fruity’ (r=0.87) and ‘bitter’ (r=0.85). The results establish that near infrared is a very useful technique that allows rapid screening of VOO samples to estimate their minor composition and sensory characteristics, and thereby their quality and commercial grade. Furthermore, it may give real time information about olive oil composition during processing in order to automatically control technological parameters.

Real time continuous oxygen concentration monitoring system during malaxation for the production of Virgin Olive Oil

During the mechanical extraction process of Virgin Olive Oil (VOO) some important physical phenomena and enzymatic transformations occur which influence the quality of the final product. The control of process parameters is crucial to ensure the quality of VOO, therefore process monitoring and control is a fundamental requirement in the modern VOO processing industry. The present work proposes an innovative Real-Time Monitoring System (RTMS) aimed at continuously measuring the oxygen concentration during the malaxation process in order to establish a correlation with the quality of the final product obtained. This monitoring system is based on an oxygen concentration sensor directly connected to the malaxation chamber and a data acquisition system to analyze and store the measured values in a process database. The experimental results obtained show that the use of oxygen during malaxation improves some qualitative parameters of VOO such as free fatty acids and total polyphenols while others (peroxide values and spectrophotometric indexes) worsen. These results are similar to those obtained by employing nitrogen, which is the traditional technique to avoid the wellknown oxidation processes studied by several researchers, thus demonstrating that the presence of oxygen during the malaxation process can have beneficial effects on the quality of VOO when its concentration is properly controlled.

Influencia del proceso de maduración del fruto en la calidad sensorial de aceites de oliva virgen de las variedades Picual, Hojiblanca y Picudo

The sensory quality of virgin olive oil is closely correlated with the cultivar and the degree of ripening of the olive fruit. The aim of the present work was to investigate the influence of ripening degree on sensory profile of monovarietal virgin olive oils (VOO) in order to establish an optimum harvesting time. Fruit obtained from three different cultivars, Picual, Picudo and Hojiblanca were picked at nine different stages of ripeness. The quality parameters were evaluated and the sensory characteristics were determinate by a sensor panel. The analytical parameters decrease slightly in all cultivars. The evolution of the organoleptic characteristics of the virgin olive oil is reported and typical flavors are described for each cultivar. In all studied cultivar, “fruity” and “bitter” attributes decreased during the ripening and conversely “sweet” attribute increased. The results showed in this work could be considered useful for providing information about the evolution of sensory quality of virgin olive oils during ripening to obtain those based on market preferences.

Identification and assay of carbohydrates in olive drupes by cesium attachment electrospray tandem mass spectrometry (ESI‐MS/MS)

Identification and assay of sugars in olive drupes during their ripening phase is evaluated by tandem mass spectrometry. Recent achievements have shown that the quality of an extra virgin olive oil can be directly correlated to the ripening degree of the drupes that is likely linked to their saccharides content. An innovation in this peculiar food chain is now proposed that considers a high throughput assessment of the carbohydrate content by a recently introduced protocol based on the gas-phase chemistry of sugar-cesium adducts by ESI-MS/MS.

Sensory Attribute Preservation in Extra Virgin Olive Oil with Addition of Oregano Essential Oil as Natural Antioxidant

Four commercial varieties of oregano are farmed in Argentina: "Compacto,""Cordobes,""Criollo," y "Mendocino." Oregano essential oil is known for antioxidant properties. The objective of this study was to evaluate changes in the intensities of positive and negative attributes in extra virgin olive oil with addition of essential oil obtained from the 4 Argentinean oregano types. Oregano essential oil was added into olive oil at 0.05% w/w. The samples were stored in darkness and light exposure during 126 d at room temperature. The intensity ratings of fruity, pungency, bitterness, oregano flavor, and rancid flavor were evaluated every 21 d by a trained sensory panel. In general, samples with addition of oregano essential oil in olive oil exhibited higher and lower intensity ratings of positive and negative attributes, respectively, during storage compared with the control samples. The first 2 principal components explained 72.3% of the variability in the olive oil samples. In general, positive attributes of olive oil were highly associated with the addition of oregano essential oil in darkness, whereas rancid flavor was negatively associated with them. Olive oil with oregano "Cordobes" essential oil was oppositely associated with light exposure treatments and negative attribute (rancid flavor) suggesting better performance as natural antioxidant of this essential oil in olive oil. The result of this study showed that the presence of oregano essential oil, specially "Cordobes" type, preserve sensory quality of extra virgin olive oil prolonging the shelf life of this product. Extra virgin olive oil is highly appreciated for its health benefits, taste, and aroma. These properties are an important aspect in this product quality and need to be preserved. The addition of natural additives instead of synthetic ones covers the present trend in food technology. This research showed that the addition of oregano essential oil preserved the intensity ratings of positive attributes in extra virgin olive oil during storage. The essential oil of the oregano variety called "Cordobes" exhibited better protecting effect on sensory properties of olive oil than the other oregano varieties. The addition of oregano essential oil should be considered for the food industry as a natural source of antioxidant additives for preserving sensory properties in extra virgin olive oil and other similar food products.

Vertical centrifugation of virgin olive oil under inert gas

AbstractVirgin olive oil vertical centrifugation under inert gas (IVC) was compared with conventional vertical centrifugation in contact with air (CVC). IVC gives a strong reduction of the oil oxygenation in terms of reduced dissolved oxygen concentration and oxidative indexes (peroxide values and K232). Minor compounds (chlorophyll and total phenols) and volatile compounds were not affected by the treatment.Practical applications: A technical implementation of inertized vertical separators appears a practicable solution to preserve virgin olive oil quality traits. This can be easily implemented both by the mill owner with homemade adjustment of the existing machines and by plant industrial manufacturers.

Compositional quality of virgin olive oils from cultivars introduced in two Tunisian locations

The aim of this study was to evaluate the quality of two European olive cultivars , ‘Koroneiki’ and ‘Arbequina’, introduced in South and North of Tunisia. Olives grown in the two locations yielded extra virgin olive oils. Northern olive oils showed a greater amount of oleic acid, phenols and a higher stability, whilst in the southern oils had higher saturated and linoleic acid content. Phenolic compounds were also influenced by the pedoclimatic conditions; hence, oils from the North had the highest level of 3,4-DHPEA-EDA and a higher content in oleuropein aglycon (3,4-DHPEA-EA) than the corresponding olive oil samples obtained from trees cultivated in South. Furthermore, the majority of the studied analytical parameters were greatly influenced by the cultivar‐environment interaction. In fact, significant differences between the studied oils were detected.

Effect of Harvesting System and Fruit Cold Storage on Virgin Olive Oil Chemical Composition and Quality of Superintensive Cultivated ‘Arbequina’ Olives

Storage at 3 and 18 °C of 'Arbequina' olives (Olea europaea L.) cultivated in hedgerows and harvested manually or mechanically (wine grape harvester) was tested. Fruit characteristics and oil quality were monitored. Mechanical harvesting caused internal fruit damage that induced its rapid softening and decay, but also facilitated obtaining higher amounts of oil, which suffered a rapid deterioration during fruit storage. This oil presented lower tocopherol and phenol contents and lower oxidative stability than the oil extracted from manually harvested olives, but showed similar fatty acid composition. Cold storage (3 °C) delayed all of these deterioration processes. It allowed maintaining the best commercial level of quality ("extra") in the oil from mechanically harvested olives for 10 days. This cold storage could be considered as an alternative to the increase in machinery for processing the growing olive production, due to both hedgerow cultivation and mechanized harvesting.

Phenolic profile of virgin olive oil from advanced breeding selections

The evaluation of the phenolic composition in advanced selections in breeding programs constitutes the first approach for selecting genotypes with improved olive oil quality. In this work, the influence of genotype and ripening index on the phenolic profile of olive oils from advanced selections in comparison to their genitors was studied. Fruit samples were collected in genotypes from crosses between ‘Arbequina’ × ‘Picual’, ‘Picual’ × ‘Arbequina’ and ‘Frantoio’ × ‘Picual’ at five dates from 1st October to 26th November 2009. Characterization of the phenolic profile was performed by liquid–liquid extraction with 60:40 (v/v) methanol–water and subsequent chromatographic analysis with absorption and fluorescence detection in a sequential configuration. A dual effect of genotype and fruit ripening on the phenolic profile has been observed with more pronounced genetic influence in both total (34.73% and 20.45%, respectively) and individual phenols (16.99% to 49.25% and 1.58% to 23.77%, respectively). A higher degree of variability between genotypes at early ripening stages was also observed (p<0.05). The obtained results also allow identification of selections with high content of total and individual phenols. These results suggest a strategy based on early harvesting of fruits (at the first three ripening indexes) for better comparison and selection of genotypes in further crosses in olive breeding programs aiming at improving the quality of virgin olive oil.

Phenolic composition of virgin olive oils from cross breeding segregating populations

AbstractThe evaluation and characterization of segregating populations is a critical step in olive breeding programs. In this work, phenolic profiles of virgin olive oils (VOOs) from segregating populations obtained by cross breeding in Cordoba (Spain) have been evaluated. Genotypes obtained from open pollination of the cultivar Manzanilla de Sevilla, and from crosses between the cultivars Arbequina × Arbosana, Picual × Koroneiki and Sikitita × Arbosana were tested. The phenolic composition was determined after liquid–liquid extraction with 60:40 v/v methanol–water and subsequent chromatographic analysis with ultraviolet (UV) detection of both absorption and fluorescence in a sequential configuration. Results for all studied compounds showed high degree of variability between genotypes, with a higher range of variation than the observed for the genitors. Most of the observed variability was attributable to differences in genotypes within crosses rather than among crosses. Some issues related to breeding strategies are discussed.Practical applications: Phenolic compounds are considered to be of paramount importance for the assessment of virgin olive oil quality due to their contribution to the nutraceutical and sensory profile of this natural food. This study focuses on the evaluation of the content of phenolic compounds in olive oils originated from cross breeding in an olive breeding program (Cordoba, Spain). This step is crucial to determine the range of variation of phenolic compounds and the selection of interesting genotypes with higher composition in total phenols or in an individual phenol targeted at a breeding program.

Cherry leafroll virus: Impact on olive fruit and virgin olive oil quality

AbstractWe performed a survey on the yield, quality, and chemical characteristics of virgin olive oils from two olive varieties in Croatian Istria: Frantoio and Ascolana tenera, on Cherry leafroll virus‐infected and virus‐noninfected trees and on two harvest dates. Free acidity, peroxide value, specific spectrophotometric absorptions at 232 and 270 nm, fatty acid composition, total phenols, o‐diphenols, oil color, and pigments were determined. Infected olives had lower oil yield and maturity index versus healthy ones. Oils from infected fruits had significant lower value of K232 and K270 and very elevated total phenols content compared to those obtained from healthy olives. Infected Frantoio gave a lower content of o‐diphenols than the healthy ones, which is in contrast to infected Ascolana that had higher values. The aim of this study is to determine the chemical changes in virgin olive oils from healthy and infected trees related to virus influence. According to our knowledge, this is the first survey on the possible influence of viruses on olive fruits, oil yield, and virgin olive oil quality.Practical applications: There are only few papers which analyze the influence of viruses on crops (especially influence on wine quality) and their effects on yield or other agronomic parameters. This work evaluates for the first time the impact of Cherry leafroll virus on the quality of virgin olive oil obtained from Frantoio and A. tenera varieties in terms of basic parameters related to the hydrolitic and oxidative status, content in antioxidant compounds, and in pigments as well as in fatty acid composition.

Influence of the Site of Cultivation on Chétoui Olive (Olea europaea L.) Oil Quality

A comparative study was conducted to evaluate the effect of location on the chemical composition and quality of monovarietal virgin olive oils obtained from the Chétoui cultivar in relation to the fruit ripening stages. Three sites representative of two Tunisian olive growing regions were examined, Selten (region I (RI): original site of plantation of Chétoui variety in the north of the country), Ousletia and Jelma (region II (RII): in the central part of the country away from the original plantation site). In this study, Chétoui olive cultivar was found to have different responses to environmental conditions. Chétoui olive oils showed lower values in phenol and o-diphenol contents and were less stable to oxidation (weaker oxidative stability and antioxidant activity levels) when the olive trees were cultivated away from the original plantation site. These Chétoui olive oils are also characterized by decreased oil content and higher values of quality parameters such as free acidity, peroxide value and UV absorbance due probably to the drought during the flowering and olive ripening periods. Furthermore, many analytical parameters, i.e., chlorophyll pigments, carotenoids, oleic acid contents, total phenol and o-diphenol amounts, oxidative stability, antioxidative capacity and quality parameters showed nearly the same changes during fruit ripening but in different degrees depending on the site of the plantation.

EVALUATION OF VIRGIN OLIVE OIL MINOR COMPOUNDS IN PROGENIES OF CONTROLLED CROSSES

ABSTRACT An experimental investigation was carried out to evaluate the quality of virgin olive oils obtained by intervarietal cross-breeding program. Twelve extra virgin olive oil cultivars were characterized by their chemical composition. The experimental data showed that new releases were characterized by an appreciable α-tocopherol (ranging from 60.09 to 153.97 mg/kg) and by a high content of total volatile compounds especially of the trans-2-hexenal. Simple phenols such as hydroxytyrosol, tyrosol, vanillic acid, p-coumaric acid, ferulic acid and vanillin were identified and quantified by high-performance liquid chromatography in most of the oils. The flavonoids compounds (apigenin and luteolin) were also found. The results indicated that a considerable oil composition variability can be achieved genetically, by breeding. PRACTICAL APPLICATIONS The olive oil characterization of the new releases is an important way to study the effect of the breeding method on their chemical composition in an attempt to select new ones with superior genotypes.