Effect of location on virgin olive oils of the two main Tunisian olive cultivars

The olive oil content in phenolic compounds depends on the variety of the fruit used for its extraction as well as on the predominant climate conditions in the tree cultivation area. Here, we report on the characterization of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivars Chemlali and Chétoui, grown in three different Tunisian locations, Zaghouan (North), Sousse (Center) and Sfax (South). Chétoui olive oil samples obtained from fruits of olive trees cultivated in Zaghouan and Chemlali olive oil samples obtained from fruits of olive trees cultivated in Sousse were found to have a higher mean total phenol content (1004 and 330 mg/kg, respectively). Olive oil samples obtained from fruits of both cultivars had different phenolic profiles and a higher content in 3,4‐DHPEA‐EDA when the olive trees were cultivated in Zaghouan. Both olive cultivars were found to have different responses to environmental conditions. Chétoui olive oil showed decreased oxidative stability when the fruits were obtained from olive trees cultivated in the center of Tunisia (34.8 h) and in Sfax (16.17 h). Furthermore, statistical data showed that the phenolic composition and oxidative stability of Chétoui olive oil varied more by location than those of Chemlali olive oils.     

Analytical evaluation of six monovarietal virgin olive oils from Northern Tunisia

The characterization of virgin olive oils from six Tunisian cultivars, namely Chétoui, Ain Jarboua, Jarboui, Regregui, Rekhami and Neb Jmel, grown in Nebeur (a region of the Kef) was carried out. These cultivars dominate their natural habitats, but with the exception of the Chétoui cultivar they are only scattered throughout the nation. Several analytical parameters were evaluated; these include quality index, fatty acid composition, chlorophylls, carotenoids, sterols, α‐tocopherol and phenolic compounds. Their relationship with oxidative stability was also tested. The main phenols found were tyrosol, hydroxytyrosol, the dialdehydic form of elenolic acid linked to tyrosol and hydroxytyrosol, oleuropein aglycon and pinoresinol. These phenolic compounds, the colorimetric total phenol content and o‐diphenols showed significant correlations with oxidative stability. Furthermore, most of the analytical parameters of the oils that were determined in this study were greatly influenced by genetic factors (cultivar).     

Preliminary chemical characterization of Tunisian monovarietal virgin olive oils and comparison with Sicilian ones

Work was carried out on the characterization of monovarietal virgin olive oils (VOO) from Tunisia and Sicily (Italy). The two main Tunisian VOO (cvv. Chétoui of the North and cv. Chemlali grown in the Center and some regions of the South) and three principal Sicilian VOO (cvv. Nocellara del Belice, Biancolilla and Cerasuola) were studied. Moreover, the Chétoui oils were tested in a rain‐fed control and an irrigation regime. All olive samples were picked at three different stages of ripeness. Analyses of major components (fatty acids and triacylglycerols) and minor ones (squalene, tocopherols and phenolic compounds) were carried out. Chétoui oils had a higher level of phenolic compounds followed by Chemlali. Generally, in the Sicilian oils these natural antioxidant contents were lower. These preliminary results indicate that it was possible to classify the Tunisian and Sicilian oils tested in their original growing area based on their chemical composition.     

Classification of virgin olive oils of the two major cretan cultivars based on their fatty acid composition

Fatty acid composition was determined for 105 virgin olive oil samples of the two dominant Cretan olive cultivars, Koroneiki and Mastoides, harvested from different producing areas at different maturity stages. The oils of the Koroneiki cultivar were characterized by lower concentrations of oleic and decaheptanoic and higher concentrations of linoleic and palmitic acids. Oils obtained from high-altitude locations were rich in monounsaturated fatty acids, while oils obtained from low-altitude locations had higher content of saturated fatty acids. Palmitic and palmitoleic acids increased with increasing altitude in both cultivars examined. The statistical analysis of the compositional data showed significant potential for the classification of the samples according to cultivar and location of origin.     

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

The 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.     

The volatile composition of samples from the blend of monovarietal olive oils and from the processing of mixtures of olive fruits

The volatile fraction deriving from the lipoxygenase pathway of samples obtained by processing olive fruits of 2 cultivars in known proportions was compared with that of samples deriving from the blending of oils extracted from the same cultivars and in the same proportions. The varieties considered for the mixtures were Coratina and Koroneiki, Coratina and Frantoio, and Dritta and Bosana, respectively. The results confirmed that the accumulation of each volatile compound from the lipoxygenase pathway in the monovarietal oils was different and closely dependent on the genetic store of each variety. The concentrations of the mentioned compounds appeared to change in a way proportional to the percent of each monovarietal oil in the samples obtained by blending 2 monovarietal oils. Instead, the oils obtained by processing mixtures of fruits from the 2 corresponding cultivars showed a striking accumulation of volatile compounds, especially of C₆‐compounds, which reached higher concentration at different percentages depending on the cultivars processed.     

Comparative study of olive oil quality from Chemlali Sfax versus Arbequina cultivated in Tunisia

The effects of the geographical region on the behavior of the Arbequina olive cultivar (cv) cultivated in the south of Tunisia (in the arid zone of Sfax) was compared to an autochthonous cultivar (Chemlali Sfax). Various olive parameters were analyzed, such as ripening index, pulp/stone ratio, oil contents, and sensory profiles. Most of the quality indices and fatty acid composition showed significant variations among olive cultivars. Arbequina cv is characterized by high oil yield with a less total phenols and pigments content than Chemlali Sfax cv. Cielab spectrophotometer coordinate L*, b*, and a* values show a great difference in olive oil colors. In spite of their low oleic acid contents, autochthonous cultivar presented a higher induction time (6.82 and 2.68 h for Chemlali and Arbequina, respectively) and high contents of phenolic compounds (158.28 and 110.27 mg/kg for Chemlali Sfax and Arbequina, respectively). The most important compounds identified were oleuropein aglycon (45.50 mg/kg), hydroxytyrosol (3.68 mg/kg), 1‐acetoxypinoresinol (6.23 mg/kg) in Chemlali Sfax oil and hydroxytyrosol glucoside (25.15 mg/kg), tyrosol (12.51 mg/kg), and oleuropein aglycon (30.60 mg/kg) in Arbequina oil. Chemlali Sfax also possessed a very bitter taste, whereas the Arbequina had a sweet taste amongst its attributes. The principal component analysis of the results indicated that the geographical region has significantly affected the olive oil quality.     

Extra Virgin Olive Oil Components and Oxidative Stability from Olives Grown in Tunisia

The effects of the contents of lipids, pigments, α-tocopherol and phenols were studied in relation to the antioxidant capacity of five virgin olive oils obtained from five olive cultivars planted in Tunisia (Arbequina, Koroneiki, Leccino, Oueslati and Chemchali). The antioxidant capacities were evaluated by two different radical scavenging activities: radical scavenging activity by the DPPH assay (RSA-DPPH) and total antioxidant status by the ABTS test (TAA-ABTS). The highest contents of antioxidant compounds (75.96, 10.34, 6.32, 15.39 and 241.52 mg kg⁻¹ for oleic acid, O/L ratio, carotenes, chlorophylls and total phenols, respectively) were found for the Koroneiki cultivar except for α-tocopherol and o-diphenols, which had the highest contents (369 and 160.7 mg kg⁻¹, respectively) in the Leccino and Chemchali cultivars (cvs). Furthermore, the highest antioxidant capacity in virgin olive oil was observed in the Koroneiki cultivar (0.24 mmol TE kg⁻¹) followed by the Chemchali and Leccino cvs (0.22 and 0.13 mmol TE kg⁻¹) for the TAA-ABTS test. However, the RSA-DPPH activity was higher for the Chemchali cultivar (19.9%) than for the Koroneiki and Leccino cvs (18.4 and 13.5%, respectively). Correlation between these capacities and the oil composition revealed that they were mainly influenced by the carotene content, followed by chlorophyll and phenolic contents where the ABTS test was more pronounced. Then, the antioxidant capacity of the virgin olive oils was correlated with polar components and the lipid profile which are important for its shelf life.     

Phenolic composition of virgin olive oils from cross breeding segregating populations

The 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.     

Oxidative Evolution of Virgin and Flavored Olive Oils Under Thermo-oxidation Processes

Changes in the oxidative status of Chétoui olive oil were monitored to attest the efficiency of some bioactive compounds from aromatic plants to improve the stability of olive oils after a maceration process at different concentrations. Aromatized olive oils were prepared by addition of lemon and thyme extracts at four different concentrations (20–80 g kg⁻¹ of oils) to virgin olive oils. The following parameters were monitored: free fatty acids, peroxide value, ultra violet absorption characteristics at 232 and 270 nm, fatty acid composition and aromatic profiles. After thermo-oxidation processes, the oleic/linoleic acid ratio remained stable (4.5). Oxidative stability slightly decreased during thermo-oxidation processes. The heating of the oils changed their volatile profile and led to the formation of new volatile compounds, such as the two isomers of 2,4-heptadienal after heating at 100 °C or (E,Z)-2,4-decadienal and (E,E)-2,4-decadienal after thermo-oxidation at 200 °C. The use of lemon and thyme extracts modified the aromatic and the nutritional value of the olive oil by the transfer of some bioactive compounds, such as limonene and carvacrol. In contrast, the oxidative stability of the product did not change. Furthermore, the aromatized oils may be employed in seasoning and cooking of some foods.     

Using lipid profiles and genotypes for the characterization of Corsican olive oils

In 2004, the Corsican producers of olive oils obtained a French protected designation of origin (PDO) “huile d'olive de Corse”, but up to now specifications of Corsican oil production do not clearly indicate the oil attributes related to the territory of production. That is why the fatty acid and triacylglycerol (TAG) compositions of olive oils from the nine main cultivars used to produce oils under PDO were determined and related to the olive variety. The results showed (i) that the nine cultivars covered only four olive varieties, as revealed by random‐amplified polymorphic DNA markers, (ii) that the lipid composition of oils is strongly dependent on the variety, and (iii) that the lipid composition of the four varieties is completely discriminated on the basis of the proportions of four TAG (OOO, OOL, PoOO, OOL) and one fatty acid (18:0). These results clearly establish the relationships between some characteristics of oils and the area of production (Corsica) for at least three varieties that are originated from Corsica. For the fourth variety, other investigations on minor compounds and on sensory attributes of oils must be undertaken to link some oil traits to the territory of production.     

Virgin Olive Oils from Super-High-Density Orchards in California: Impact of Cultivar,Harvest Time,and Crop Season on Quality and Chemical Composition

The impact of cultivar, harvest time, and crop season on olive fruit characteristics and olive oil quality and minor components composition is assessed for super-high-density “Arbequina”, “Arbosana”, and “Koroneiki” in California, United States, during 2016, 2017, and 2018. Fruit oil content reaches a plateau in November for “Arbequina” and “Arbosana,” while the accumulation rate keeps constant until early December for “Koroneiki.” Free fatty acids, diacylglycerols, pyropheophytins, and ΔK are not affected by any of the considered factors. Peroxide value, K_232, and K₂₇₀ decreases with harvest time. Chlorophylls content decreases with harvest time, more rapidly in “Arbequina” and “Arbosana” than in “Koroneiki”. Cultivar is the main factor affecting the fatty acid profile. “Koroneiki” has the highest oleic acid content, followed by “Arbosana” and “Arbequina.” Phenolic and volatile compounds are profoundly affected by cultivars and crop seasons, suggesting the relevance of these factors on the sensory and nutritional properties of virgin olive oil from super-high-density cultivars. Stepwise linear discriminant analysis allows selecting suitable markers among fatty acids, phenolic, and volatile compounds for cultivar, crop season, and harvest time discrimination. Practical Application: This paper constitutes the first report of a multiyear study considering quality and composition in bioactive compounds of super-high-density “Arbequina,” “Arbosana,” and “Koroneiki,” planted in California, USA. This information helps processors understand the differences in oil made from the most common super-high-density cultivars along harvest times and for growers to make planting and harvesting decisions.     

Chemometric classification of olive cultivars based on compositional data of oils

European Union regulations provide important guidelines for maintaining the Protected Designation of Origin (PDO) of olive oil and other foods. This includes characterization of foods based on variety (cultivar) and geographical origin, as this may be used as a criterion for determining authenticity and quality. Therefore, analytical method standards need to be established to ensure these criteria. This study describes how cultivar differences can be established between Italian oils, obtained from single varieties, based on acid, sterol, and TAG differences determined by chemometrics. TAG and FA composition provided the best basis for differentiation of olive oils among cultivars. The results were compared with those obtained using ¹³C NMR analysis, and a similar differentiation between oils of different cultivars was achieved. ¹³C NMR provides useful information on the acyl composition and on the positional distribution of the glycerol moiety and can be used for classification of cultivars based on oil composition. Furthermore, the advantages of this technique come from the rapidity with which information can be obtained and from the very simple preparation procedure required for analysis.     

The Effect of Harvesting Time on Olive Fruits and Oils Quality Parameters of Tortiglione and Dritta Olive Cultivars

Despite the fact that Italy holds the most important olives heritage in the world, with about 800 cultivars, most of them are still underestimated, in particular those from Abruzzo, a region located in the center of the peninsula. The aim of this work is to study the changes in quality parameters of olive fruits and related oils of two autochthonous Abruzzo olive cultivars, Tortiglione and Dritta during ripening (from September to November 2017). Both cultivar and ripening time affect the chemical parameters of olive fruits. Results highlight an increasing trend of the oil content with final values, based on fresh matter, of 38.7 ± 0.3% and 38.1 ± 0.9% for Tortiglione and Dritta, respectively. Olive oils chemical composition is also affected by ripening time and cultivar, with Tortiglione oils resulting generally richer than Dritta oils; on the first sampling time (30th of October) values for total phenolic content, antioxidant activity, and chlorophylls are 803.8 ± 68.2 mg gallic acid equivalent kg⁻¹, 2.7 ± 0.5 mmol trolox equivalent kg⁻¹, and 30.8 ± 1.6 mg pheophytin a kg⁻¹, respectively. Tocopherols seem to be more affected by ripening time than by cultivar, in particular for Dritta. Practical Application : The results on Abruzzo minor olive cultivars indicate that olive fruits and olive oil composition are strongly influenced by both cultivar and ripening time, giving rational indications about the optimal cultivar specific harvesting time and opening interesting opportunities for olive oil producers in a perspective of sustainable production to obtain high quality fruits and oils. The research provides detailed information about Tortiglione and Dritta olive cultivar, useful in the global context of revaluation of Italian minor olive varieties.     

GxE Effects on Tocopherol Composition of Oils from Very Old and Genetically Diverse Olive Trees

Tocopherols are compounds with high biological activity, beneficial for human health that can be found in vegetable oils like olive oil, contributing for its resistance to oxidation. In this work, the tocopherol contents of olive oils extracted from centenarian olive trees of six cultivars (cvs. Lentisca, Madural, Rebolã, Redondal, Verdeal, and Verdeal Transmontana) were evaluated during five consecutive crop seasons (2013–2017). Three tocopherol isoforms (α-, β- and γ-tocopherols) were detected in all analyzed olive oils, and their content varied significantly with the cultivar and year of production. The highest amounts were found in cv. Lentisca (456 ± 122 mg/kg olive oil), while the lowest were observed in cv. Verdeal (179 ± 45 mg/kg olive oil). Crop year was the most influential factor, with the highest contents observed in 2013 and lowest in 2014. Principal component analysis and hierarchical clustering analysis helped differentiate olive oils according to cultivar or production year. These data suggest that tocopherol composition may serve as a chemical marker to distinguish the subject cultivar olive oils from centenarian trees either by olive cultivar or by crop year, being some cultivars identified as potential candidates for guaranteeing the production of olive oils rich in these compounds.     

Quality and Composition of Virgin Olive Oils from Indigenous and European Cultivars Grown in China

The characteristics of eight varieties of virgin olive oil (Arbosana, Arbequina, Coratina, Cornicabra, Frantoio, Koroneiki, Picual, and Ezhi 8) obtained in two successive crops in the southwest of China (Xichang, Sichuan Province) were investigated. Significant differences (P < 0.05) were observed in physicochemical properties, fatty acid profile, minor component contents, and oxidative stability between different varieties of olive oils. The physicochemical properties of all samples met IOC standards for extra virgin olive oil, while in Koroneiki, olive oils were present the optimum oxidation stability among studied varieties. The results of hierarchical cluster analysis and principal component analysis (PCA) showed a good classification between varieties based on their qualitative characteristics. Koroneiki and Ezhi 8 olive oils were significantly different from other varieties mainly due to color, fatty acid profile, and minor components. PCA result also showed that harvest crop influences the characteristics of samples mainly due to the variance of temperature and rainfall.     

Chemical composition of commercial cornicabra virgin olive oil from 1995/96 and 1996/97 crops

The chemical composition of commercial Cornicabra virgin olive oils (n=65) was studied, as was its relationship with oil quality and the influence of the extraction method and production year. The main characteristics of these olive oils were: oxidative stability 53 ± 24 h, mean polyphenol content 162 ± 57 mg/kg (as gallic acid), oleic acid 80.8 ± 0.9%, linoleic acid 4.6 ± 0.6%, and campesterol 4.3 ± 0.1%, which is peculiar to this variety. No clear differences in composition were observed with respect to the different extraction systems (dual-phase/triple-phase decanters and pressure), although oils produced by the dual-phase decanter showed higher oxidative stability and polyphenol content. There were significant differences in major fatty acids and sterols according to the production year.     

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

In 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.     

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

We 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.     

Fatty acids,volatiles, sterols and triterpenic alcohols of six monovarietal Tunisian virgin olive oils

Fatty acids, volatiles, sterols, aliphatic and triterpenic alcohols of six monovarietal Tunisian virgin olive oils were analyzed. The results suggested that the compositional data concerning the above analytical fractions were effective in discriminating between varieties. The oils were found to contain high levels of oleic acid (up to 71.70% in the Oueslati variety). β‐Sitosterol (up to 85.46% in the Jdallou variety) and Δ5‐avenasterol (up to 30.97% in the El Hor variety) were the principal sterols in all samples; campesterol and stigmasterol were found at low levels. (E)‐2‐Hexenal was the main compound that characterizes the olive oil headspace of all samples. The other compounds identified were mainly C₆ aliphatic components.