Phenols and Volatiles of Istarska Bjelica and Leccino Virgin Olive Oils Produced with Talc,NaCl and KCl as Processing Aids

The effect of processing aids (2.5 % of talc, NaCl or KCl) on oil extractability and the profile of phenolic and volatile compounds of Istarska bjelica and Leccino oils was studied. Talc significantly increased extractability in both cultivars, while salts increased extractability in Leccino cv. In the laboratory extracted oils, phenols were determined by a RP‐HPLC–DAD method, whereas volatiles were determined by SPME/GC–MS. Talc addition significantly decreased hydroxytyrosol and increased ligstroside derivatives in produced oils, but did not affect the total phenol content. Among volatile compounds, only Z‐2‐penten‐1‐ol in Leccino and 1‐pentene‐3‐one in Istarska bjelica oils significantly increased by talc addition. Salts improved transfer of most individual phenols into oil, particularly oleuropein derivatives, and increased C6 aldehydes and C5 volatiles in Leccino oils. NaCl exerted a stronger effect in increasing individual phenols and volatiles than KCl.     

Effect of Agronomical Practices on the Nutritional Quality of Virgin Olive Oil at Different Ripening Stages

There is a need to verify the quality of organically produced olive oils and to compare them to conventional ones. The objective of this study was to assess possible differences in nutritional quality between agronomic practices in Picual and Hojiblanca olive oil varieties at different stages of olive ripeness. The results showed that organic versus conventional cultivation did not consistently affect acidity, peroxide index or spectrophotometric constants of the virgin olive oils considered in this study. On the contrary, phenol content, oxidative stability, tocopherol content and fatty acid composition were affected by the agronomical practices. Principal component analysis indicated that linolenic acid and β‐tocopherol were mainly responsible for discriminating Hojiblanca organic oils, whereas total phenols, palmitoleic acid and α‐tocopherol were the major contributors to differentiating Picual conventional oils. Lignoceric and stearic acids were related to oils from unripe and ripe olive fruits, respectively. Long‐term experiments are required to confirm these results.     

Authentication of Commercial Extra Virgin Olive Oils

The goal of the current contribution is to determine the geographical origins of olive oil samples obtained from eight different countries during the harvest seasons of 2013 and 2014. First, the contents of olive oil samples were quantified by integrating the peaks of ¹H‐NMR spectra and using linear mathematical equations. The results were analyzed by analysis of variance (ANOVA), a statistical method examining whether there is a significant difference between the groups mean. The origins of the majority of the olive oil samples were discriminated by ANOVA and the minor constituents of the olive oils. Tocopherol and cycloartenol were the most discriminative minor constituents of the olive oil samples.     

Biochemical Characterization of Turkish Extra Virgin Olive Oils from Six Different Olive Varieties of Identical Growing Conditions

Extra virgin olive oils were extracted from six different major olive cultivars (Gemlik, Ayvalik, Domat, Akhisar, Memecik, Arbequina) cultivated in the Aegean region of Turkey. Fatty acid, sterol and tocopherol compositions were analyzed and the results were compared by multivariate statistical analysis. Olive samples were collected from the same orchard in order to limit the contribution of parameters such as climate, soil quality and agricultural practices to the total variance of chemical composition of olive oils. Principal component analysis (PCA) showed that cultivars can be clearly distinguished on the basis of fatty acid and sterol composition. It is of interest to note that palmitoleic acid content of Arbequina, a Spanish cultivar, is significantly (p < 0.05) higher than the local Turkish cultivars in question and it is the only olive sample whose palmitoleic acid concentration is higher than that of the stearic acid concentration, exhibiting a divergent composition from the local Turkish cultivars. β‐Sitosterol and Δ5‐avenasterol contents of the oils are significantly correlated (r = ?0.989, p < 0.05) and this results in a discriminative axis on the PCA loading plot. Tocopherol composition was relatively insufficient in discriminating the olive varieties. Regarding tocopherol compositions Gemlik cultivar is distinguished from other cultivars with its γ‐tocopherol content, which is in average two times higher than that of other cultivars. The result of the present compositional study provides important data which can be used for olive oil authenticity studies in Turkey.     

The Effect of Different Cold Storage Conditions on the Compositions of Extra Virgin Olive Oil

Storage conditions can affect the stability and quality of extra virgin olive oil (EVOO). While many studies have reported the influence of high temperature and light exposure during storage, little is known on the influence of the cold storage. The aim of this study was to evaluate the effect of different storage conditions (25, 4.5 and ?27 °C) on the various compositions of EVOO and to determine if cold storage will prolong shelf‐life by retarding hydrolysis and oxidation. The changes of quality indices (FFA, PV, and UV) and natural antioxidants such as α‐tocopherol and phenolic compounds were evaluated periodically during storage. The characterization and quantification of phenolics were achieved by ultra‐performance liquid chromatography—diode array detector (UPLC‐DAD). In addition, 1, 2‐diacylglycerols (DAGs), pyropheophytin A (PPP) were measured to indicate thermal degradation during storage.     

Effect of Clarification System on the Conservation of Virgin Olive Oil during Its Storage

The results obtained in this work explain how clarification systems can affect the conservation of virgin olive oils (VOOs) during the storage step. The evolution of the quality and sensory properties during the storage of VOOs clarified by different systems, vertical centrifugal separator (VCS) with minimal water addition and conical bottom settling tank (CBST), is studied at industrial scale for two different crop years. In general, VCS oils show a slight higher moisture and solid impurities content at the end of the storage step due to a higher emulsion grade (because of the emulsion generated) caused by the rotating movement of this clarification system. For the studied clarification systems, no remarkable differences are observed between the oils during their storage for quality indexes. However, these systems show differences regarding oil sensory properties. The VOOs clarified by VCS are characterized by a higher presence of phenol components, higher positive sensory attributes intensity, and higher lipoxygenase (LOX) aldehydes content during their storage. VOOs from CBST show lower phenol content, a higher “non‐LOX” volatiles content, and the presence of sensory defects during storage. Practical Applications: The results obtained in this work are very important in order to provide specific recommendations and scientific support based on objective data to improve VOO quality. As described in this study, the VCS with a minimal water addition can be a better option to produce VOO of improved quality. This clarification system is an efficient and quick operation that reduces the contact between oil and the remaining water and impurities during the storage step. The minimal water addition used in this clarification system allows obtaining VOOs with higher phenol content and positive sensory notes. This leads to prolong VOO shelf‐life and conservation during the storage stage, due to preservation of the quality indexes and minor components with antioxidant activity. Besides, this clarification system reduces the water consumption during oil clarification and generates a lower wastewater volume regarding conventional vertical centrifugation, and therefore can be considered more environmentally friendly.     

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.     

Fatty Acid Profiles of Virgin Olive Oils from the Five Olive-Growing Zones of Extremadura (Spain)

In this study, 278 samples of virgin olive oil from 40 mills belonging to five olive-growing zones of Extremadura were evaluated according to their fatty acid composition. An analysis of variance of the fatty acid contents, and their principal group subtotals and ratios revealed significant differences at the 95 % confidence level between zones. Means were compared using Tukey’s HSD test (p < 0.05). A discriminant analysis, taking the zone as the grouping variable and the different fatty acids and their ratios as independent variables, explained nearly 90 % of the variance with the first two functions. The model correctly classified 88.8 % of the analysed samples into their proper olive-growing zone. Validation against an extra test set of 30 samples resulted in 90 % being correctly classified; the results of the discriminant analysis were therefore considered to be validated. A two-dimensional graphical representation of the different groups studied using the first two resulting canonical discriminant functions clearly showed the Sierra Norte of Cáceres and Vegas del Guadiana each to be clearly separated from the rest and from each other, while the other three zones—Siberia, Serena and Tierra de Barros—overlapped considerably.     

The Effect of Boron Application on Chemical Characterization and Volatile Compounds of Virgin Olive Oil of Ayvalik Olive Cultivar

In this study, the Ayvalik olive variety, an important and widely grown olive variety in Turkey, was chosen. A month prior to blooming and 2 months prior to harvesting in 2011 and 2012, three different concentrations of boron (100, 150 and 250 ppm) were applied to the olive leaves with or without boron deficiencies. After the application, quality criteria, fatty acid composition, total phenol contents and major volatile compounds of olive oil that was obtained from the harvested olives were investigated. Boron application to the olive trees with boron deficiencies has improved both the amount and the olive oil quality. Experimental results show the significance of boron for olive farming. Application of boron in 150 ppm led to a better olive oil quality by improving fatty acid composition [oleic acid (76.03 %), linoleic acid (9.68 %), linolenic acid (0.56 %), monounsaturated fatty acid (77.24 %)], total phenol content (422.94 ppm) and major volatile compounds [E‐2‐hexenal (43.12 ppm), hexanal (3.02 ppm), Z‐3‐hexenol (1.13 ppm)] in both harvest seasons (2011–2012) and in both olive orchards with or without boron deficiencies.     

Investigation of the Effects of Virgin Olive Oil Cleaning Systems on the Secoiridoid Aglycone Content Using High Performance Liquid Chromatography–Mass Spectrometry

Phenolic compounds are useful markers to control olive oil technological processes, including the virgin olive oil (VOO)/water separation after olive oil extraction. In this investigation, VOO extracted from olives of cv. Coratina using a mild oil/water separator called the hydrocyclone sedimentation system (Hydroil) was compared with VOO obtained using a conventional vertical centrifuge separator (Cenoil), which is mostly used in the modern olive oil industry. Secoiridoid aglycones were selected, among phenolic compounds, as markers and analyzed using reversed‐phase liquid chromatography coupled to linear quadrupole ion‐trap mass spectrometry with electrospray ionization in the negative mode. VOO samples obtained using the Hydroil system were found to contain significantly higher levels of secoiridoid aglycones, compared to the Cenoyl‐type samples. In particular, the total content of the aglycones of decarboxymethyl oleuropein, decarboxymethyl ligstroside, ligstroside, and oleuropein, expressed in terms of oleuropein, was estimated as 35.40 ± 0.80 mg kg^?1, compared to 8.06 ± 0.41 mg kg^?1 in the Cenoil samples (n = 3). Since no significant difference in residual water (P < 0.05) was found between the two types of VOO samples, the higher amount of secoiridoids obtained for Hydroil‐type ones was explained by the lower extent of oxidation occurring during the mild oil/water separation achieved using the Hydroil system.     

Characterization of Turkish Virgin Olive Oils Produced from Early Harvest Olives

Olives were collected from various districts of Turkey (North and South Aegean sub-region, Bursa-Akhisar, South East Anatolia region) harvested over seven (2001–2007) seasons. The aim of this study was to characterize the chemical profiles of the oils derived from single variety Turkish olives including Ayvalik, Memecik, Gemlik, Erkence, Nizip Yaglik and Uslu. The olive oils were extracted by super press and three phase centrifugation from early harvest olives. Chosen quality indices included free fatty acid content (FFA), peroxide value (PV) and spectrophotometric characteristics in the ultraviolet (UV) region. According to the FFA results, 46% (11 out of 24 samples) were classified as extra virgin olive oils; whereas using the results of PV and UV, over 83% (over 19 of the 24 samples) had the extra virgin olive oil classification. Other measured parameters included oil stability (oxidative stability, chlorophyll pigment, pheophytin-α), cis–trans fatty acid composition and color index. Oxidative stability among oils differed whereas the cis–trans fatty acid values were within the national and international averages. Through the application of two multivariate statistical methods, Principal component and hierarchical analyses, early harvest virgin olive oil samples were classified according to the geographical locations categorized in terms of fatty acid profiles. Such statistical clustering gave rise to defined groups. These data provide evidence of the variation in virgin olive oil quality, especially early harvest and cis–trans isomers of fatty acid profiles from the diverse agronomic conditions in the olive growing regions of Turkey.     

Effect of Light Exposure on the Quality and Phenol Content of Commercial Extra Virgin Olive Oil during 12-Month Storage

Storage conditions influence the maximum time for which the composition and sensory characteristics of olive oils can be guaranteed. The purpose of this research was to study the quality and phenol content of extra virgin olive oil (EVOO) after storage for 1 year in different types of containers under darkness or light. Three Spanish cultivars with quantitatively different phenol contents were selected for the study. Storage under light conditions impaired the physicochemical and sensorial properties of the three cultivars, and reduced total phenolics, but there was an increase in hydroxytyrosol and tyrosol concentrations. It also markedly decreased their total phenolic content, especially when kept in polyethylene containers exposed to light, with reductions ranging from 4.28% for vanillic acid in Picual oils stored in dark glass containers under dark conditions to 97.82% for ferulic acid in Arbequina oils stored in polyethylene containers under light conditions. There was a reduced concentration of flavonoid and lignan concentrations after 1 year of storage, with the greatest decrease (98.01% of initial content) being observed for in the flavonoid apigenin. These results indicate that EVOO should be stored in dark glass containers under dark conditions for the optimal preservation of its quality and phenol content.     

Effects of Cultivars and Location on Quality, Phenolic Content and Antioxidant Activity of Extra-Virgin Olive Oils

Quality characteristics of extra-virgin olive oils depend on several factors. In order to study the effects of genotype and growing location on olive oil quality, olives from cv. Coratina, Nocellara, Ogliarola, and Peranzana, picked in four locations of the Apulia region (Italy), were crushed by a three-phase system to produce mono-cultivar extra virgin olive oils that were analyzed for acidity, peroxide value, spectrophotometric indices, total phenolic content, phenolic profile and antioxidant activity. The experimental data concerning peroxide value, spectrophotometric indices, phenolic content and profile and antioxidant activity showed great variability among the cultivars grown in the same location and also among the oils produced with olives of the same cultivar but grown in different locations. For each cultivar, no significant differences were found among locations in terms of acidity and ΔK whereas peroxide value, K₂₃₂, and K₂₇₀ differ significantly among locations for both Ogliarola and Peranzana cv. Concerning the phenolic content of Ogliarola cv., no differences were highlighted between the locations whereas the phenolic contents of Peranzana significantly changed as a function of the place of growing. On the basis of these results, the statistical multivariate analysis did not allow the classification into homogeneous groups neither of the oils belonging to the same cultivar nor of those obtained from olives picked in the same location.     

Effects of Olive Trees Age on the Minor Components of Oueslati Virgin Olive Oils Produced from Olives Harvested at Different Ripening Degrees

Phenolics, volatiles, squalene, tocopherols, and fatty acids of virgin olive oils (VOO) from adult and young olive trees of the Oueslati variety, typically cultivated in the Center of Tunisia, were analyzed at three different harvesting periods. Significant differences in contents of saturated fatty acids (p < 0.05), squalene (p < 0.05), alpha-tocopherol and total tocopherol (p < 0.02) and oxidized form of decarboxymethyl oleuropein aglycon (p < 0.05) were seen between VOO from adult and young trees during maturation. Moreover, the volatile profiles of VOO from adult and young trees showed significant differences in the amounts of hexanal, 1-penten-3-ol (p < 0.05), (Z)-3-hexenal and (Z)-2-penten-1-ol (p < 0.01). Principal component analysis showed that olives from adult trees should be harvested at the cherry stage of maturation to obtain a satisfactory level of oil quality, while olives from young trees should be harvested at the black maturation stage.     

Studies on the Detection of Oleuropein from Extra Virgin Olive Oils Using Enzymatic Biosensors

Oleuropein (OLEU) is an important indicator of the quality and authenticity of extra virgin olive oils (EVOO). Electrochemical sensors and biosensors for the detection of oleuropein can be used to test the adulteration of extra virgin olive oils. The present study aimed at the qualitative and quantitative determination of oleuropein in commercial EVOO samples by applying electrochemical techniques, cyclic voltammetry (CV) and square wave voltammetry (SWV). The sensing devices used were two newly constructed enzyme biosensors, supported on single-layer carbon-nanotube-modified carbon screen-printed electrode (SPE/SWCNT) on whose surface tyrosinase (SPE/SWCNT/Tyr) and laccase (SPE/SWCNT/Lac) were immobilized, respectively. The active surfaces of the two biosensors were analyzed and characterized by different methods, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) and the results confirmed the efficient immobilization of the enzymes. SPE/SWCNT/Tyr was characterized by a low detection limit (LOD = 9.53 × 10⁻⁸ M) and a very good sensitivity (0.0718 μA·μM⁻¹·cm⁻²) over a wide linearity range from 0.49 to 11.22 μM. The process occurring at the biosensor surface corresponds to kinetics (h = 0.90), and tyrosinase showed a high affinity towards OLEU. The tyrosinase-based biosensor was shown to have superior sensitive properties to the laccase-based one. Quantitative determination of OLEU in EVOOs was performed using SPE/SWCNT/Tyr and the results confirmed the presence of the compound in close amounts in the EVOOs analysed, proving that they have very good sensory properties.     

Effects of Filtration on the Quality Properties of Extra Virgin Olive Oils during Storage

In this study, the effects of filtration on quality parameters, chemical characteristics, antioxidant activity, and oxidative stability (OS) of Turkish olive oils during the storage period of 12 months were investigated. The olive oil free acidity (% oleic acid per 100 g of olive oil) (free fatty acidity, FFA), peroxide values (PV) (meq O₂ kg⁻¹ oil), and UV spectrophotometric indices (K₂₃₂ and K₂₇₀ measurements) were used for evaluating the quality parameters of olive oils. α-tocopherol analysis, total phenolic content (TPC), total chlorophyll and carotenoid analyses, and 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical-scavenging activity (RSA) assays were carried out. Chromatographic methods were applied to determine the fatty-acid and triacylglycerol (TAG) composition, the content of methyl and ethyl esters (FAEE and FAME), and the content of fatty acids of olive oils. Univariate and multivariate statistical methods were performed to evaluate results. Univariate data analysis results showed that filtration of Ayvalık, Memecik, and Domat olive oils had no considerable influence on quality parameters, antioxidant compounds, FAEE and FAME, antioxidant activity, and OS, except TPC (P < 0.05). A significant difference between the samples was determined regarding storage times of the olive oils. Principal component analysis (PCA) analysis revealed that olive oils were grouped according to storage periods of the olive oils regarding fatty-acid and triacylglycerol (TAG) composition while there was no clear separation among the samples according to the filtration process. However, qualitative and quantitative changes took place on minor and major components of olive oils during the storage period.     

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.     

Impact of Olive Harvesting Date on Virgin Olive Oil Volatile Composition in Four Spanish Varieties

The unique sensory characteristics of extra virgin olive oil (EVOO) depend upon its volatile composition. This work investigates the impact of olive fruit harvesting time and growing location on the volatile composition of the obtained EVOO, on four typical Spanish olive varieties (Cornicabra, Picual, Castellana, Manzanilla Cacereña). Several growing locations within the Madrid region (Spain) are studied to assess the natural variability attributed to the environmental factors. Aroma compounds are analyzed by solid-phase microextraction coupled with gas-chromatography and mass spectrometry, and sensory analysis. A considerable different behavior is observed depending on the olive variety and ripening stage. Statistically significant differences are obtained for volatile compounds biosynthesized from the lipoxygenase pathway and other fatty acid metabolism routes, which results in significant differences in their aroma profiles. Practical applications: These results have practical applicability for the olive oil industry and regulatory bodies. For example, for protected designation of origin EVOOs the aroma profile needs to be consistent over different production lots. The outcome of this research is of interest to the olive oil industry to get a better insight into the expected variability and interactions among cultivars, small pedoclimatic differences within the same broader area, and the harvesting date on the sensory and volatile profile of the resulting EVOO.     

Bioactive Compounds of Portuguese Virgin Olive Oils Discriminate Cultivar and Ripening Stage

The presence of different bioactive compounds in virgin olive oil affects its nutritional, oxidative and sensorial properties. Phenolic compounds are olive endogenous bioactive compounds highly susceptible to degradation. Olive endogenous oxidoreductases, mainly polyphenol oxidases (PPO) and peroxidases (POD), may play an important role on the profile of bioactive compounds in olive oil by promoting oxidation of phenolic compounds. The aim of this study was to evaluate if changes on PPO and POD activities in olive fruits from two Portuguese cultivars (Olea europaea, cv ‘Cobrançosa’ and cv ‘Galega Vulgar’) are related with the composition of their olive oils, especially phenolic compounds. Pattern recognition techniques [principal component analysis (PCA), cluster analysis (CA), and discriminant analysis (DA)] were used for multivariate data analysis. Olive oils characterized by their FA composition were grouped by cultivar. When olive oils were characterized by their phenolic composition, green pigments, and enzymatic activities in fruits, they could be discriminated by olive ripening stage. Along ripening, PPO activity was only detected in the fruit mesocarp of both cultivars and POD activity was mainly detected in the seeds. The POD activity, as well as vanillin and gamma‐tocopherol contents in olive oil increased with the ripening index. Conversely, higher PPO activity in fruits at early ripening stages together with higher levels of total phenols, green pigments, beta‐tocopherol, hydroxytyrosol and p‐coumaric acid in olive oils were observed. The ripening stage of fruits showed to be a key factor on the amount and profile of bioactive compounds of olive oil.