•Purification of sterols and triperpene dialcohols in olive oils.•Use of a polymeric reversed phase and a silica gel direct phase SPE.•Silica gel SPE column with 10–12 µm particle size.•The improved ...method is simple, time-saving and reduce the amount of solvents used.•Use of 2,2-dimethoxypropane to maintain constant the activity of the silica gel.
The sterols and triterpene dialcohols composition is an important parameter to assess the authenticity of the high value and prone to adulteration extra virgin olive oil. The official methods used to carry out this analysis are time-consuming, labor-intensive and require a high amount of solvents. In this work a simple and time-saving method, based on two solid phase extraction (SPE) steps was developed. After oil saponification, the unsaponifiable matter was purified by polymeric SPE and then the sterols and triterpene dialcohols were isolated by an in-house packed small particle silica gel SPE and analyzed by GC-FID. Results obtained analyzing a sample of extra virgin olive oil, olive oil and refined olive pomace oil with the proposed method showed a good agreement with those obtained with the International Olive Council (IOC) official method. Thus, the use of the proposed method allows a rapid screening for extra virgin olive oils authentication.
•Oleacein is the major phenol in ‘Galega Vulgar’ and ‘Cobrançosa’ virgin olive oils.•Low hydroxytyrosol and tyrosol contents indicate fresh virgin olive oils.•‘Galega Vulgar’ olive oil is richer in ...gama-tocopherol than ‘Cobrançosa’ olive oil.•‘Cobrançosa’ olive oil has higher flavonoid content than ‘Galega Vulgar’ olive oil.
In this study, the lipophilic and hydrophilic phenol composition of virgin olive oils (VOO) obtained from olives from two of the most important Portuguese cultivars (‘Galega Vulgar’ and ‘Cobrançosa’), harvested at different ripening stages and under two irrigation schemes (rain fed and irrigated), was evaluated. Phenolic alcohols (hydroxytyrosol and tyrosol), phenolic acids and derivatives and flavonoids (luteolin and apigenin), as well as tocopherols were quantified. Lipophilic (>300mgkg−1) and hydrophilic phenols (>600mgkg−1) were present in high contents in both VOO, for early ripening stages. Gamma-tocopherol content is higher in ‘Galega Vulgar’ VOO. Total phenols showed a decrease between ripening index 2.5 and 3.5. The dialdehydic form of elenolic acid linked to hydroxytyrosol (3,4-DHPEA-EDA), also known as oleacein, was the major phenolic compound identified in both oils. The concentration of free hydroxytyrosol and tyrosol in both VOO is very low while their esterified derivatives, like 3,4-DHPEA-EDA and p-HPEA-EDA, are much more abundant.
Numerous studies have been carried out on the bioactive properties of hydroxytyrosol (HT) in olive oils (OOs), although there are few reports comparing anti-inflammatory activity among different ...olive varieties or regions of production. The purpose of this study was to investigate the
inflammatory action of HT in extracts of four OO varieties in the Languedoc region of the French Mediterranean. Factors other than cultivar were eliminated, which enabled unambiguous varietal differences to be identified. Purified extracts of OO were obtained using an optimized solid-phase extraction procedure by which only polar compounds were recovered. High performance liquid chromatography-photodiode array detection-tandem mass spectrometry was used to identify and quantify HT and oleacein in the extracts. The total polyphenol concentration ranged from 93.00 mg gallic acid equivalent/kg OO for Picholine to 27 mg gallic acid equivalent for Verdale OOs. The concentrations of HT in Picholine, Olivère, and Lucques varieties were 25.3, 18.8 and 12.1 mg/kg, respectively, whereas the concentration of HT in Verdale OOs was less, 1 mg/kg. The
anti-inflammatory response of purified OO extracts, evaluated by the inhibition of nitric oxide release in lipopolysaccharide-induced interferon-
activated J774.A1 macrophages, strongly correlated with total polyphenol content (
> 0.995). The effect increased asymptotically between the equivalent of 2 and 37 mg of OO, reaching, at the maximum tested concentration, 90%, 75%, 62%, and 30% activity for Picholine, Olivière, Lucques, and Verdale, respectively. The results presented here clearly show that, by comparison with authentic standards, the activity of HT in OO extracts was enhanced in a concentration-dependent manner, varying from 3-fold at the highest extract concentration to over 6.5-fold at the lowest extract concentration. Therefore, the anti-inflammatory activity of OOs should be rationalized on the basis of whole extracts rather than solely on the concentration of HT or other bioactive compounds in OO.
This paper aims to study the volatile composition of monovarietal extra-virgin olive oils from different varieties from Alentejo region (Portugal). Volatile profile of 82 olive oils was performed by ...head-space solid phase micro-extraction hyphenated with gas chromatography/mass spectrometry (HS-SPME-GC/MS). A total of 107 volatile compounds, belonging to several class of compounds, like aldehydes, hydrocarbons, alcohols, terpenoids, ketones, sulphurous compounds, acids and esters were identified, assigned to a specific biogenic origin and total abundances were plotted in modified 3D van Krevelen diagrams. The 3D plots showed that there are compositional differences among olive oil varieties. Discriminant analysis confirmed that the pattern of volatile compounds includes enough information to group sample variety amongst discrete monovarietal olive oil. Combining statistical analysis (t-Student) and graphical-tools (van Krevelen diagram) seems to be a powerful tool to determine what molecular families were characteristic of each olive oil variety, contributing to the valorization of monovarietal Portuguese olive oil.
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•The volatile profile of different monovarietal olive oils was traced by HS-SPME.•3D van Krevelen diagrams showed differences between olive oil varieties.•Specific chemical families are characteristic to each type of olive oil variety.
•Fatty acid composition of the Galician oils was between usual Arbequina and Picual oils.•Brava olives had a markedly higher content in all relevant C6 compounds.•Pungent and bitter were the main ...sensory attributes in oils with a higher percentage of Brava.•Volatiles from amino acid transformation and acetic acid penalized Mansa virgin oils.•Useful recommendations for olive oil producers to improve the quality of oils were given.
The interest of Galician oil producers (NW Spain) in recovering the ancient autochthonous olive varieties Brava and Mansa has increased substantially in recent years. Virgin olive oils produced by co-crushing both varieties in two different proportions, reflecting the usual and most common practice adopted in this region, have gradually emerged for the production of virgin olive oils. Herein, the sensory and chemical characteristics of such oils were characterized by quality and genuineness-related parameters. The results of chemical analysis are discussed in terms of their effective contribution to the sensory profile, which suggests useful recommendations for olive oil producers to improve the quality of oils. Antioxidant compounds, together with aromas and coloured pigments were determined, and their contribution in determining the functional value and the sensory properties of oils was investigated. In general, given the high levels of phenolic compounds (ranging between 254 and 375mg/kg oil), tocopherols (about 165mg/kg oil) and carotenoids (10–12mg/kg oil); these are oils with long stability, especially under dark storage conditions, because stability is reinforced with the contribution of chlorophylls (15–22mg/kg oil). A major content of phenolic compounds, as well as a predominance of trans-2-hexen-1-al within odor-active compounds (from 897 to 1645μg/kg oil), responsible for bitter sensory notes. This characterization allows to developing new antioxidant-rich and flavour-rich VOOs, when co-crushing with a higher proportion of Brava olives, satisfying the consumers’ demand in having access to more healthy dishes and peculiar sensory attributes.
The present study investigates the aroma, key odorants and sensory profile of extra virgin olive oils from five well-known Turkish cultivars. The aromatic extract obtained by the purge and trap ...extraction system, according to a sensory analysis, resembled the odor of olive oil. A total of 22, 21, 18, 22 and 21 aroma-active compounds were detected in the extracts of Ayvalık, Memecik, Gemlik, Sarı Ulak and Beylik olive oils, respectively. The results show that Ayvalık has the highest flavor dilution (FD) value of 1024 with hexanal, (E)-2-hexenal and α-farnesene. Memecik has the highest FD value at 2048 with (E)-2-hexenal. Gemlik has the highest FD value of 1024 with (Z)-3-hexenyl acetate, (E)-2-hexen-1-ol and α-farnesene. Sarı Ulak has the highest FD value at 2048 with (E)-2-hexenal. Beylik has the highest FD value of 2048 with (E)-2-hexenal and hexanal. All cultivars represent the characteristic green, cut-grass, fruity odor notes.
Introduction
Olive oil, derived from the olive tree (Olea europaea L.), is used in cooking, cosmetics, and soap production. Due to its high value, some producers adulterate olive oil with cheaper ...edible oils or fraudulently mislabel oils as olive to increase profitability. Adulterated products can cause allergic reactions in sensitive individuals and can lack compounds which contribute to the perceived health benefits of olive oil, and its corresponding premium price.
Objective
There is a need for robust methods to rapidly authenticate olive oils. By utilising machine learning models trained on the nuclear magnetic resonance (NMR) spectra of known olive oil and edible oils, samples can be classified as olive and authenticated. While high‐field NMRs are commonly used for their superior resolution and sensitivity, they are generally prohibitively expensive to purchase and operate for routine screening purposes. Low‐field benchtop NMR presents an affordable alternative.
Methods
We compared the predictive performance of partial least squares discrimination analysis (PLS‐DA) models trained on low‐field 60 MHz benchtop proton (1H) NMR and high‐field 400 MHz 1H NMR spectra. The data were acquired from a sample set consisting of 49 extra virgin olive oils (EVOOs) and 45 other edible oils.
Results
We demonstrate that PLS‐DA models trained on low‐field NMR spectra are highly predictive when classifying EVOOs from other oils and perform comparably to those trained on high‐field spectra. We demonstrated that variance was primarily driven by regions of the spectra arising from olefinic protons and ester protons from unsaturated fatty acids in models derived from data at both field strengths.
This study compares the performance of partial least squares discrimination analysis (PLS‐DA) models trained on low‐field (LF) and high‐field (HF) nuclear magnetic resonance (NMR) spectra when distinguishing extra virgin olive oil (EVOO) from other edible oils. When predicting on an external dataset, LF NMR models were highly effective in classifying EVOO and had predictive performance comparable to HF models. These findings support LF NMR trained machine learning algorithms as a rapid, cost‐effective tool for EVOO authentication.
The aim of the study was to determine the stability and heat resistance of extra premium olive oil. The study material consisted of six extra virgin olive oils (EVOO) obtained from Spain. Four ...samples were single-strain olive oils: Arbequina, Picual, Manzanilla, and Cornicabra. Two samples were a coupage of Arbequina and Picual varieties: Armonia (70% Arbequina and 30% Picual) and Sensation (70% Picual and 30% Arbequina). Olive oil samples were heated at 170 °C and 200 °C in a pan (thin layer model). In all samples, changes in indexes of lipid nutritional quality (PUFA/SFA, index of atherogenicity, index of thrombogenicity, and hypocholesterolemic/hypercholesterolemic ratio), changes in tocopherol, total polar compounds content, and triacylglycerol polymers were determined. Heating olive oil in a thin layer led to its degradation and depended on the temperature and the type of olive oil. Increasing the temperature from 170 to 200 °C resulted in significantly higher degradation of olive oil. At 200 °C, deterioration of lipid nutritional indices, total tocopherol degradation, and formation of triacylglycerol polymers were observed. A twofold increase in the polar fraction was also observed compared to samples heated at 170 °C. The most stable olive oils were Cornicabra and Picual.
Aroma profiles, key aroma compound quantification, and cluster analysis of 15 brands of extra-virgin olive oils (EVOOs) from three countries (Spain, Italy, and Greece) were investigated in the ...current study. Aroma compounds were isolated from the oil by using solvent-assisted flavor evaporation (SAFE) and solid-phase micro-extraction (SPME) and analyzed by gas chromatography-olfactometry mass spectrometry (GC-MS/O). A total of 89 compounds were screened by SPME/SAFE-GC-MS/O with chromatographic columns in 15 brands of samples. Eighty and 54 compounds were respectively identified by SPME- and SAFE-GC-MS/O. Of those, 44 compounds were detected by both methods. Undecanol, (Z)-4-decenal, (E)-2-dodecenal, and 2-nonanone extracted by SAFE were not found in EVOOs before. Eight classes of aroma compounds were identified, including 17 alcohols, 22 aldehydes, 9 ketones, 4 acids, 14 esters, 5 aromatics, 12 alkene, and 6 others. Eleven compounds were identified as the key aroma compounds in alternative brands of EVOOs by SAFE-aroma extract dilution analysis (AEDA). Hexanal, (E)-2-hexenal, (E)-3-hexenol, acetic acid, and (E)-2-heptenal were the common key aroma compounds by AEDA and odor activity values (OAVs). From the cluster analysis of the heatmap, the aroma compounds of all the Spain EVOOs were similar, and there were some differences from the samples of Italy and Greece. It suggested that both the amount and concentration of aroma compounds determine the similarity of aroma in EVOOs.
The olive oil composition of eleven cultivars (cvs. Arbequina, Arbosana, Arroniz, Cornicabra, Frantoio, Hojiblanca, Manzanilla, Picual, Picudo, Redondilla and Royuela) cultivated in a high-density ...olive grove located in a non-traditional producing region (Valladolid, Spain) was studied during four consecutive crop seasons. The results showed that the 122 monovarietal olive oils studied could be classified as extra virgin oils, according to the quality parameters. Furthermore, the olive cultivar had a marked effect on the chemical composition and antioxidant activity. In general, olive oils from cvs. Picual and Cornicabra showed the highest total phenolic contents, oxidative stability, and tocopherols contents, whereas the worst results for oxidative stability were observed for cv. Redondilla olive oils, probably associated to the lowest contents of phenolics and tocopherols and the highest amounts of polyunsaturated fatty acids. Finally, it was found that, despite the different crop years evaluated, the quality-chemical profiles could be used to successfully discriminate the monovarietal oils under study (linear discriminant analysis sensitivities: 92 ± 5% for the repeated K-fold cross-validation), using the data of 15 non-redundant variables identified by the simulated annealing variable selection algorithm.
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