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1.
Fourier transform infrared (FT‐IR) spectroscopy in combination with chemometric techniques has become a useful tool for authenticity determination of extra‐virgin olive oils. Spectroscopic analysis of monovarietal extra‐virgin olive oils obtained from three different olive cultivars (Erkence, Ayvalik and Nizip) and mixtures (Erkence‐Nizip and Ayvalik‐Nizip) of monovarietal olive oils was performed with an FT‐IR spectrometer equipped with a ZnSe attenuated total reflection sample accessory and a deuterated tri‐glycine sulfate detector. Using spectral data, principal component analysis successfully classified each cultivar and differentiated the mixtures from pure monovarietal oils. Quantification of two different monovarietal oil mixtures (2–20%) is achieved using partial least square (PLS) regression models. Correlation coefficients (R2) of the proposed PLS regression models are 0.94 and 0.96 for the Erkence‐Nizip and Ayvalik‐Nizip mixtures, respectively. Cross‐validation was applied to check the goodness of fit for the PLS regression models, and R2 of the cross‐validation was determined as 0.84 and 0.91, respectively, for the two mixtures.  相似文献   

2.
The antioxidant properties of some single components and the total antioxidant activity of extra‐virgin olive oil have been evaluated by the oxygen radical absorbance capacity (ORAC) method. The total ORAC of the extra‐virgin olive oil was found to be positively correlated with the concentration of total polyphenols, which are important to the shelf life of the product. Among the single phenolic compounds studied, gallic acid showed a higher ORAC than caffeic acid and oleuropein, while among the derivates of oleuropein, hydroxytyrosol was found to be the most active compound among all the phenols studied. The total ORAC of commercial olive oils differed according to the concentration of total polyphenols. The total ORAC of extra‐virgin olive oil was constant during 1 year of storage in rational conditions, whereas it worsened dramatically in olive oil damaged by the lipase‐producing yeast Williopsis californica or by lipase from Pseudomonas spp. The study accomplished on the oily fraction of the fruits before harvesting demonstrated that the total ORAC of the oil of under‐ripe green olives is higher compared to that shown by mature fruits; therefore, through the choice of the harvesting time, it is possible to define also the future content of polyphenols of the oil. The total ORAC test, together with other analyses, can be considered as a qualitative parameter that can contribute to the expression of technological and health virtues of extra‐virgin olive oil.  相似文献   

3.
The effect of heating at 180 °C on the antioxidant activity of virgin olive oil (VOO), refined olive oil (ROO) and other vegetable oil samples (sunflower, soybean, cottonseed oils, and a commercial blend specially produced for frying) was determined by measuring the radical‐scavenging activity (RSA) toward 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH?). The RSA of the soluble (polar) and insoluble (non‐polar) in methanol/water fractions of olive oil samples was also measured. The stability of heated oils was assessed by determining their total polar compound (TPC) content. VOO was the most thermostable oil. Total polar phenol content and the RSA of VOO heated for 2.5 h decreased by up to 70 and 78%, respectively, of their initial values; an up to 84% reduction in RSA of VOO polar and non‐polar fractions also occurred. Similar changes were observed in the RSA of ROO and its non‐polar fraction after 2.5 h of heating. The other oils retained their RSA to a relatively high extent (up to 40%) after 10 h of heating, but in the meantime they reached the rejection point (25–27% TPC). The results demonstrate that VOO has a remarkable thermal stability, but when a healthful effect is expected from the presence of phenolic compounds, heating has to be restricted as much as possible.  相似文献   

4.
The factors influencing the oxidative stability of different commercial olive oils were evaluated. Comparisons were made of (i) the oxidative stability of commercial olive oils with that of a refined, bleached, and deodorized (RBD) olive oil, and (ii) the antioxidant activity of a mixture of phenolic compounds extracted from virgin olive oil with that of pure compounds andα-tocopherol added to RBD olive oil. The progress of oxidation at 60°C was followed by measuring both the formation (peroxide value, PV) and the decomposition (hexanal and volatiles) of hydroperoxides. The trends in antioxidant activity were different according to whether PV or hexanal were measured. Although the virgin olive oils contained higher levels of phenolic compounds than did the refined and RBD oils, their oxidative stability was significantly decreased by their high initial PV. Phenolic compounds extracted from virgin olive oils increased the oxidative stability of RBD olive oil. On the basis of PV, the phenol extract had the best antioxidant activity at 50 ppm, as gallic acid equivalents, but on the basis of hexanal formation, better antioxidant activity was observed at 100 and 200 ppm.α-Tocopherol behaved as a prooxidant at high concentrations (>250 ppm) on the basis of PV, but was more effective than the other antioxidants in inhibiting hexanal formation in RBD olive oil.o-Diphenols (caffeic acid) and, to a lesser extent, substitutedo-diphenols (ferulic and vanillic acids), showed better antioxidant activity than monophenols (p- ando-coumaric), based on both PV and hexanal formation. This study emphasizes the need to measure at least two oxidation parameters to better evaluate antioxidants and the oxidative stability of olive oils. The antioxidant effectiveness of phenolic compounds in virgin olive oils can be significantly diminished in oils if their initial PV are too high.  相似文献   

5.
The effect of extraction systems on the phenolic composition of virgin olive oils obtained from two different Italian cultivars (Coratina and Oliarola) was determined. The oils extracted using two-phase centrifugation showed in all cases higher phenolic concentration in comparison to oils obtained from three-phase centrifugation. In particular, the highest differences were observed for aglykone derivatives of oleuropein (3,4-DHPEA-EDA and 3,4-DHPEA-EA) that are the most concentrated antioxidant phenolic compounds of virgin olive oil. These results were confirmed by the autoxidation stability of the oils examined.  相似文献   

6.
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.  相似文献   

7.
Virgin olive oil has high levels of phenolic compounds that are highly bioavailable; these compounds are receiving considerable attention for their antioxidant activity, closely related to the prevention of non‐communicable chronic diseases. The aim of this work was to characterize the phenolic profile and antioxidant capacity of monovarietal olive oils cvs. Arauco, Arbequina, Farga and Empeltre produced in Argentina. This study focused on the relationship between the single molecules or classes of molecules quantified by SPE‐CZE, the corresponding Folin‐Ciocalteu results, and antioxidant capacity using three different tests. Fifteen compounds were simultaneously determined: tyrosol, vinylphenol, oleuropein, hydroxytyrosol, rutin, catechin, naringenin, cinnamic acid, chlorogenic acid, syringic acid, luteolin, apigenin, vanillin acid, quercetin, and caffeic acid. The phenolic contents of the monovarietal olive oils show significant differences between different varieties (p < 0.05), with positive and significant Pearson's correlation found between Folin–Ciocalteu and CZE. Besides, the correlation between the content of total polyphenols and antioxidant capacity was high for all the antioxidant assays performed. When analyzing the correlation coefficients of the different families of phenolic compounds studied, simple phenols and cinnamic acid derivatives show a higher correlation with antioxidant capacity. Thus, findings obtained in this study demonstrated that Arauco olive oil, autochthonous for Argentina, possesses the highest antioxidant/free‐radical scavenging properties, which are very likely due to the presence of high contents of phenolic compounds.  相似文献   

8.
Polar extracts of extra‐virgin olive oils (EVOO) contain a large number of phenolic compounds with antioxidant properties. The antioxidant capacity can be measured by different reaction mechanisms, as the single electron transfer (SET) or the hydrogen atom transfer (HAT). In this work, the total phenolic content (TPC) by the Folin‐Ciocalteu method and its correlation with four antioxidant capacity assays (FRAP, ABTS, DPPH? and ORAC) were evaluated for EVOO polar extracts. It was observed that the higher the total phenolic compounds in the EVOO extracts, the higher the antioxidant capacities, regardless of the method employed. The reaction mechanism observed for TPC by Folin‐Ciocalteu method and also for FRAP, ABTS and DPPH? antioxidant capacity assays is a single electron transfer, thus, a high correlation among their results is expected. However, the correlation between TPC and ORAC results was also high and significant, allowing to conclude that EVOO phenolic compounds are able to react by the hydrogen atom transfer mechanism, which indicates that they can act as effective radical chain‐breaking antioxidants. These results suggest that, for the EVOO polar extracts, TPC by Folin‐Ciocalteu and ORAC assays could be sufficient to evaluate their in vitro antioxidant capacity.  相似文献   

9.
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.  相似文献   

10.
Although large amounts of olive oil are produced in Turkey, not much information on its chemical composition is available in the literature to date. The aim of this study was to evaluate the chemical composition of commercial olive oils produced from the Ayvalik olive cultivar in Canakkale, Turkey. Five different samples corresponding to the olive oil categories of extra virgin (conventional, extra virgin olive oil (EVOO), and organic extra virgin olive oil (OGOO) production), virgin olive oil (OO-1), ordinary virgin olive oil (OO-2) and refined olive oil (RFOO) were evaluated. Olive oils were collected from two consecutive production years. According to the free fatty acids, the absorbance values (K232 and K270), and peroxide values of all the samples conformed to the European standards for olive oil. The level of oleic acid was in the range of 68–73%; while the linoleic acid content was significantly lower in the refined olive oils. The tocopherol and polyphenol content was in the lower range of some European olive oils. However, pinoresinol was a major phenolic compound (5–77 mg/kg depending on the oil category). Its content was markedly higher than in many other oils, which would be a useful finding for olive oil authentication purposes.  相似文献   

11.
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.  相似文献   

12.
Olive oil composition has been investigated using chemical approaches, since the composition has a direct impact on its quality and safety and it may be used for certification purposes. In this paper, eleven monovarietal and twelve commercial Portuguese olive oils were analyzed to determine spectrophotometrically their total polyphenol content, ortho-diphenols and antioxidant activity. The phenolic profiles of these olive oils were also studied by high performance liquid chromatography. The lowest phenolic content and antioxidant activity were observed for monovarietal olive oils, however, among these group, ‘Cobrançosa’ and ‘Redondil’ cultivars showed the highest values of these two chemical parameters. In commercial olive oils, the concentration of polyphenols, determined according to the Folin–Ciocalteu method, and the antioxidant activity (ABTS method) ranged from 97.37 ± 1.10 to 219.7 ± 1.50 mg GAE/kg of oil and from 387.2 ± 20.00 to 997.5 ± 30.90 µmol Trolox/kg, respectively. The study of the phenolic profile demonstrated that the highest concentrations of the most abundant compounds in olive oil (tyrosol, hydroxytyrosol and oleuropein) are present in commercial olive oils. The correlation coefficient between total phenolics and antioxidant activity was statistically significant (r = 0.95, p < 0.0001). The same was observed for ortho-diphenol content and antioxidant capacity (r = 0.94, p < 0.0001).  相似文献   

13.
In this study, the effect of deep fat frying on oil degradation, total phenols (TP) and total antioxidant activity (TAA) of hazelnut, corn, soybean and olive oils were investigated. Oil degradation and oxidation were monitored by measuring the total polar compounds (TPC) and the peroxide value (PV). The amount of TPC in corn, soybean and olive oils increased significantly with the time increment (p < 0.05). The PV of the oils did not exceed the maximum acceptable limit of 10 mequiv O2/kg after 125 min frying except for hazelnut oil (10.64 mequiv O2/kg). Deep-fat frying did not cause any significant change in the TP of corn oil, soybean oil and olive oil (p < 0.05). A significant decrease in the antioxidant activity was observed after 50 min frying using hazelnut oil and corn oil (p < 0.05). However, the antioxidant activity of soybean oil and olive oil significantly decreased after 75 and 25 min frying, respectively.  相似文献   

14.
The main objective of this study was to evaluate the effect of different deficit irrigation treatments (control, regulated deficit irrigation [RDI]‐1, RDI‐2, and RDI‐3) on the phenolic profile of the olive paste and oil content. Irrigation treatments with more stress water led to a considerable increase in the phenolic compounds of olive paste, especially in oleuropein (60.24%), hydroxytyrosol (82%), tyrosol (195%), and verbascoside (223%) compared to control. A significant increase in the content of total flavonoids and phenolic acids was also observed for these samples. In virgin olive oils (VOO) elaborated from the most stressed olive trees (RDI‐2 and RDI‐3), a noticeable increase in phenolic substances with antioxidant properties (oleuropein, hydroxytyrosol, tyrosol, secoiridoid derivatives, and o‐vanillin) was observed. Consequently, water stress conditions improved antioxidant activity of VOO.  相似文献   

15.
The effect of filtration and dehydration on the stability and quality of virgin olive oil during storage at room temperature (25 °C) and under accelerated conditions (40 °C) was studied. Different types of monovarietal olive oil, namely unfiltered (UF), filtered (F) and filtered‐dehydrated (FD), were obtained from Arbequina, Colombaia, Cornicabra, Picual and Taggiasca cultivars. Results showed that filtration and dehydration decreased the rate of hydrolysis of the triacylglycerol matrix, especially at the higher temperature and in oils with a higher initial free acidity (e.g. free acidity of 0.82% and 0.63% in UF and FD Colombaia samples, respectively, after 8 months of storage), and delayed the appearance of rancid defects (e.g. UF and FD Arbequina samples lost extra‐virgin grade after 10 and 12 months of storage, respectively). The formation of simple phenols due to the hydrolysis rate of their secoiridoid derivatives was also greater in unfiltered olive oils (e.g. 174 μmol/kg and 137 μmol/kg in UF and FD Picual samples, respectively, after 8 months of storage). Thus, filtration and especially dehydration could help to prolong the shelf life of high‐quality and less stable olive oils like those obtained from the Arbequina and Colombaia varieties.  相似文献   

16.
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.  相似文献   

17.
The aim of this work was to study, under different conditions, degradation of secoiridoids during extraction of extra virgin olive oil by following the effect of ascorbic and citric acid addition. Their effect was evaluated on oil obtained from both damaged olives and undamaged fresh olives. Addition of enzyme inhibitors to damaged olives during olive milling allowed us to obtain oil with a higher phenolic compound content. Conversely, addition of the same inhibitors to undamaged fresh olives, during oil milling, resulted in no significant improvement in the phenolic compound content of oil. A high presence of PPO was thus indirectly confirmed, as damaged olives were only found to be sensitive to action of inhibitors. Ascorbic acid was found to be more effective than citric acid in preserving phenolic compounds of oil. Trials on undamaged fresh olives confirmed occurrence of hydrolytic transformation phenomena for secoiridoids during extra virgin olive oil production process. In particular, the quantitatively most representative component for Frantoio cultivar was found to be 3,4‐DHPEA‐EDA. This compound may be considered a direct marker for the degree of transformation of secoiridoids during production process. Practical applications: The processing of undamaged olives resulted in the extraction of extra virgin olive oil with a higher phenol content. It could be indirectly inferred that a reduced activity of PPO caused a low secoiridoid degradation both before and after malaxation. Lightly scratched, overripe olives could be used in those markets where the addition of oxidation‐inhibiting substances is allowed. Using inhibitors can be suggested for olive washing step.  相似文献   

18.
The effect of the addition of olive leaf (Olea europaea, cv. Arbequina) extracts, i.e. hydroalcoholic (ethanol–water 1:1; OHE), juice (OJ) and supercritical fluid‐CO2 (OSFE) on the oxidative stability of vegetable oils with different unsaturation, such as soybean oil (SBO), canola oil (CO) and high oleic sunflower oil (HOSO), were studied at two concentrations (250 and 630 mg/kg oil, expressed as caffeic acid equivalent (CAE)). The extracts were characterized by the total phenolic content (Folin–Ciocalteau method), phenol chromatographic profiles (LC‐MS) and antioxidant activity (DPPH). OHE showed the highest phenol content (7.7 mg CAE/mL) while OJ and OSFE showed values of 5.4 and 2.2 mg CAE/mL, respectively. Oleuropein and its derivatives were the major phenolic compounds identified in OHE. The addition of 630 mg CAE/kg oil of OHE and OSFE to HOSO, SBO and CO showed an antioxidant effect, increasing significantly the induction time (IT) (p<0.05). That effect was highest when the system was more monounsaturated. In contrast, OJ showed a pro‐oxidant effect for all oils systems for both concentration studied. This behaviour could be attributed to the diphenol oxidase (PPO) activity.  相似文献   

19.
We report a study on the chemical characterization of 102 monovarietal micro‐extracted and genetically characterized extra virgin olive oils (EVOOs) from Coratina, Ogliarola Barese and Cima di Mola cultivar, according to “Terra di Bari” (Apulia, southeast Italy) PDO requirement. Three additional geographical mentions, all belonging to the same Bari district (Bitonto, Castel del Monte and Murgia dei Trulli e delle Grotte), were studied and potential microclimate differences were evaluated. Our results indicate the possibility of distinguishing EVOOs from the same “Terra di Bari” PDO with respect to different cultivars and (to some extent) different subareas. In particular, two cultivars (Ogliarola Barese and Coratina), obtained from the same Bitonto area, and a single cultivar (Coratina), obtained from Bitonto and Castel del Monte subareas, were compared to investigate the micro‐area pedoclimatic effect. Finally, 1H NMR data were found significant for classification purposes of unknown EVOO samples, the results of which were included in the model space, as they were correctly predicted by the OPLS‐DA obtained by 1H NMR data. This work aims to classify commercial “Terra di Bari” PDO EVOOs by comparison of the declared cultivar and geographical origin with a reference dataset of genetically characterized micro‐extracted monovarietal oils. In conclusion, the effect of the pedoclimatic micro‐areas of origin on the Coratina cultivar, which is the main component of the “Terra di Bari” PDO, has been studied in order to improve the traceability of the raw material used to produce this valuable food.  相似文献   

20.
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.  相似文献   

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