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1.
The initial stability of virgin olive oil depends on various factors, among which are the variety and the degree of fruit ripeness. The former, which genetically determines the composition of the olive and its oil, also marks, to some extent, its stability. However, oil stability changes as the olive ripens, so it is obvious that the degree of ripeness is an important factor. The oils were obtained by the Abencor system. Acidity, peroxide index, UV absorption at 232 and 270 nm, sensory analysis, fatty acid composition, tocopherols, phenolic compounds, orthodiphenolic compounds, sterols, pigments, and oxidative stability were determined, and the results were analyzed statistically. During ripening there was a decrease in all of the parameters studied except linoleic acid, Delta-5-avenasterol, and oil content, which increased. Virgin oils showed very good correlation between stability and the concentrations of total phenols, o-diphenols, tocopherols, chlorophyll pigments and carotenoids, linoleic and linolenic acids, total sterols, beta-sitosterol, and Delta-5-avenasterol.  相似文献   

2.
Capillary electrophoresis (CE) can be effectively used as a fast screening tool to obtain qualitative and semiquantitative information about simple and complex phenolic compounds of extra virgin olive oil. Three simple phenols (tyrosol, hydroxytyrosol, and vanillic acid), a secoiridoid derivative (deacetoxy oleuropein aglycon), and two lignans (pinoresinol and acetoxypinoresinol) were detected as the main compounds in extra virgin olive oils by high-performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE). Spectrophotometric indices, radical scavenging activity, and oxidative stability of extra virgin olive oil samples obtained from olives hand-picked at different ripening degrees were statistically correlated with the CZE and HPLC quantification. The concentration of phenols in extra virgin olive oil decreased with ripeness of olive fruits. The high correlations found between CZE and the other analytical results indicate that CE can be applied as a rapid and reliable tool to routinely determine phenolic compounds in extra virgin olive oils.  相似文献   

3.
This study investigated the effect of both the degree of ripening of the olive fruit and irrigation management-rain-fed, two different regulated deficit irrigations (RDI), the method proposed by the Food and Agriculture Organization of the United Nations (known as FAO), and 125 FAO (125% FAO)-on the phenolic and volatile composition of Cornicabra virgin olive oils obtained during two crop seasons. Secoiridoid phenolic derivatives greatly decreased upon increase of both irrigation and ripening, for example, the 3,4-DHPEA-EDA content decreased from 770 to 450 mg/kg through fruit ripening under rain-fed conditions and from 676 to 388 mg/kg from rain-fed conditions to FAO irrigation treatment (at a ripeness index of approximately 4). Moreover, secoiridoid derivatives of hydroxytyrosol decreased more than those of tyrosol. The levels of major volatile components decreased in the course of ripening but were higher in irrigated olive oils: for example, the E-2-hexenal content ranged between 4.2 and 2.6 mg/kg (expressed as 4-methyl-2-pentanol) over fruit maturation under rain-fed conditions and between 8.0 and 3.5 mg/kg under FAO scheduling. It is important to note that where water was applied only from the beginning of August (RDI-2), when oil begins to accumulate in the fruit, the resulting virgin olive oil presented a phenol and volatile profile similar to those of the FAO and 125 FAO methods, but with a considerable reduction in the amount of water supplied to the olive orchard.  相似文献   

4.
The activity of olive microbiota during the oil extraction process could be a critical point for virgin olive oil quality. With the aim to evaluate the role of microbiological activity during the virgin olive oil extraction process, just before oil extraction freshly collected healthy olive fruits were immersed in contaminated water from an olive mill washing tank. The oils extracted were then compared with control samples from the same batch of hand-picked olives. The presence of lactic and enteric bacteria, fungi and Pseudomonas on the surface of olives was proved to be much higher in washed than in control olives, with increments in cfu/g between 2 and 3 orders of magnitude. The biogenesis of volatile compounds and the extraction of olive polyphenols and pigments were significantly influenced by the microbiological profile of olives even without any previous storage. In most cases the effect of olive microbiota on oil characteristics was greater than the effect exerted by malaxation time and temperature. Oils from microbiologically contaminated olives showed lower amounts of C5 volatiles and higher levels of C6 volatiles from the lipoxygenase pathway and some fermentation products. On the other hand, a decrease of chlorophylls, pheophytins, xanthophylls and the ratio chlorophyll/pheophytin was observed in these oils. Likewise, the microbiological activity during oil extraction led to significantly lower amounts of polyphenols, in particular of oleuropein derivatives. These differences in olive oil chemical composition were reflected in oil sensory characteristics by the decrease of the green and bitter attributes and by the modification of the oil color chromatic ordinates.  相似文献   

5.
Olives (Olea europaea) of the Manzanilla and Verdial varieties, harvested at the green mature stage of ripening, were heated at 30, 40, 45, and 50 degrees C during 24 h and at 40 degrees C during 24, 48, and 72 h, respectively. Just after treatments, oils were physically extracted from the olives. Olive heating promotes a reduction of oil bitterness in direct relationship to the time and temperature used. Fruit heating at < or =40 degrees C during 24 h did not produce significant changes of acidity, UV absorption, peroxide index, panel test score, or oxidative stability of the obtained oils. Both longer treatments at 40 degrees C and heating at >40 degrees C yielded oils with less oxidative stability. Oils obtained from olives heated at > or =40 degrees C showed higher concentrations of chlorophylls and carotenes. For each olive variety, a good correlation between oil bitterness and content of hydroxytyrosol secoiridoid derivatives was found.  相似文献   

6.
The processing factors (pesticide concentration found in olive oil/pesticide concentration found in olives) of azinphos methyl, chlorpyrifos, lambda-cyhalothrin, deltamethrin, diazinon, dimethoate, endosulfan, and fenthion were determined in olive oil production process in various laboratory-scale olive oil extractions based on three- or two-phase centrifugation systems in comparison with samples collected during olive oil extractions in conventional olive mills located at different olive oil production areas in Greece. Pesticide analyses were performed using a multiresidue method developed in our laboratory for the determination of different insecticides and herbicides in olive oil by solid-phase extraction techniques coupled to gas chromatography detection (electron capture detection and nitrogen phosphorus detection), optimized, and validated for olive fruits sample preparation. Processing factors were found to vary among the different pesticides studied. Water addition in the oil extraction procedure (as in a three-phase centrifugation system) was found to decrease the processing factors of dimethoate, alpha-endosulfan, diazinon, and chlorpyrifos, whereas those of fenthion, azinphos methyl, beta-endosulfan, lambda-cyhalothrin, and deltamethrin residues were not affected. The water content of olives processed was found to proportionally affect pesticide processing factors. Fenthion sulfoxide and endosulfan sulfate were the major metabolites of fenthion and endosulfan, respectively, that were detected in laboratory-produced olive oils, but only the concentration of fenthion sulfoxide was found to increase with the increase of water addition in the olive oil extraction process.  相似文献   

7.
A total of 33 virgin olive oil samples of the two main Tunisian cultivars, Chemlali and Chétoui, were characterized by their volatile compounds. The olive oil samples were obtained from olives harvested at four stages of ripeness in costal and inland farms of different geographical places. Major volatiles, mostly C6 and C5 compounds produced from linolenic and linoleic acids through the lipoxygenase cascade, were quantified by solid-phase microextraction-gas chromatography. Mathematical procedures allowed for the determination of the volatiles that not only are able to discriminate the olive oils by their olive cultivar (hexanal, E-2-hexenal, and total ketones) and ripeness (pentanal and 1-penten-3-one) but also contribute to their distinctive aroma. Finally, an electronic nose based on metal oxide sensors was checked for a rapid and at-line implementation of Tunisian olive oil varietal traceability. The classification of the samples by the sensors was explained by their sensitivity to volatiles E-2-hexanal, hexanal, 1-penten-3-one, ethanol, and Z-3-hexenol. Multivariate procedures of discriminant analysis and principal component analysis were used in the study.  相似文献   

8.
The phenolic fraction of virgin olive oil influences both its quality and oxidative stability. One of the principal threats of the quality of olive fruit is the olive fly ( Bactrocera oleae) as it alters the chemical composition. The attack of this olive pest has been studied in order to evaluate its influence on the quality of virgin olive oil (free acidity, peroxide value, fatty acid composition, water content, oxidative stability, phenols, and antioxidant power of phenolic fraction). The study was performed using several virgin olive oils obtained from olives with different degrees of fly infestation. They were acquired in different Italian industrial mills from the Abruzzo region. Qualitative and quantitative analyses of phenolic profiles were performed by capillary electrophoresis-diode array detection, and electrochemical evaluation of the antioxidant power of the phenolic fraction was also carried out. These analyses demonstrated that the degree of fly attack was positively correlated with free acidity ( r = 0.77, p < 0.05) and oxidized products ( r = 0.58, p < 0.05), and negatively related to the oxidative stability index ( r = -0.54, p < 0.05) and phenolic content ( r = -0.50, p < 0.05), mainly with secoiridoid compounds. However, it has been confirmed that the phenolic fraction of olive oil depends on several parameters and that a clear correlation does not exist between the percentages of fly attack and phenolic content.  相似文献   

9.
The influence of the preliminary steps in olive oil production (harvesting and washing) on pesticide residues in olives and olive oil has been investigated. Analyses were performed by GC-MS/MS and revealed that endosulfan sulfate and two herbicides (diuron and terbuthylazine) were the most frequently found residues in olives and olive oil. The harvesting method has a decisive influence on herbicide concentrations found in olives. Thus, 16 and 48% of the olive samples harvested on the ground after falling from the tree presented concentrations higher than the maximum residue limit (MRL) for diuron and terbuthylazine, respectively. In olives harvested directly from the tree, diuron was not found at concentrations higher than MRL and terbuthylazine was found in only 10% of the samples. The washing step performed routinely in olive mills was effective in removing the superficial contamination by herbicides present in olives harvested on the ground. Nevertheless, even after washing, the olive oil obtained from ground olives showed herbicide residue concentrations higher than those obtained from tree olives.  相似文献   

10.
The Mediterranean diet appears to be associated with a reduced risk of several chronic diseases including cancer and cardiovascular and Alzheimer's diseases. Olive products (mainly olive oil and table olives) are important components of the Mediterranean diet. Olives contain a range of phenolic compounds; these natural antioxidants may contribute to the prevention of these chronic conditions. Consequently, the consumption of table olives and olive oil continues to increase worldwide by health-conscious consumers. There are numerous factors that can affect the phenolics in table olives including the cultivar, degree of ripening, and, importantly, the methods used for curing and processing table olives. The predominant phenolic compound found in fresh olive is the bitter secoiridoid oleuropein. Table olive processing decreases levels of oleuropein with concomitant increases in the hydrolysis products hydroxytyrosol and tyrosol. Many of the health benefits reported for olives are thought to be associated with the levels of hydroxytyrosol. Herein the pre- and post-harvest factors influencing the phenolics in olives, debittering methods, and health benefits of phenolics in table olives are reviewed.  相似文献   

11.
The production of olive oil yields a considerable amount of waste water, which is a powerful pollutant and is currently discarded. Polyphenols and other natural antioxidants, extracted from olives during oil extraction process, partially end up in the waste waters. Experimental and commercial olive oil waste waters from four Mediterranean countries were analyzed for a possible recovering of these biologically interesting constituents. Identification and quantitation of the main polyphenols were carried out by applying HPLC-DAD and HPLC-MS methods. Representative samples of ripe olives were also analyzed at the same time to correlate, if possible, their polyphenolic profiles with those of the corresponding olive oil waste waters. The results demonstrate that Italian commercial olive oil waste waters were the richest in total polyphenolic compounds with amounts between 150 and 400 mg/100 mL of waste waters. These raw, as yet unused, matrices could represent an interesting and alternative source of biologically active polyphenols.  相似文献   

12.
In this study, the structural features and ripening-related changes that occur in the arabinan-rich pectic polysaccharides highly enmeshed in the cellulosic matrix of the olive pulp fruit were evaluated. These pectic polysaccharides, obtained from two consecutive harvests at green, cherry, and black ripening stages, account for 11-19% of the total pectic polysaccharides found in the olive pulp cell walls and were previously shown to occur as calcium chelating dimers. On the basis of the 13C NMR, (1H, 13C) gHSQC, 2D COSYPR, and (1H,13C) gHMBC carbon and proton resonances of the variously linked arabinosyl residues, we propose a tentative structure. This structure is particularly characterized by T-beta-Araf (1-->5)-linked to (1-->3,5)-Araf residues and by the occurrence of branched and linear blocks in the arabinan backbone. Methylation analysis showed that these pectic polysaccharides of black olives have more arabinan side chains, which were shorter (less (1-->5)-Araf), highly branched (more (1-->3,5)-Araf), and with shorter side chains (fewer (1-->3)-Araf) than those of green and cherry olives. Quantitative 13C NMR data indicated that these modifications involved the disappearance of the characteristic terminally linked beta-Araf residue of the arabinans. This odd feature can be used as a diagnostic tool in the evaluation of the stage of ripening of this fruit, as well as a marker for the presence of olive pulp in matrices containing pectic polysaccharides samples.  相似文献   

13.
The evolution of 1,3- and 1,2-isomers of diacylglycerols (DGs) in olive oils obtained from healthy olives and the influence of the olive quality was studied. Healthy olive fruits yielded oils containing almost exclusively 1,2-isomers whereas altered olives produced oils with significant amounts of 1,3-isomers. Virgin olive oils obtained from various olive cultivars and stored at different temperatures showed triacylglycerol hydrolysis and diacylglycerol isomerization depending on the acidity and temperature. The results indicated that the relationship between acidity and total diacylglycerol content has scarce utility for detecting mild refined oil in virgin olive oil. On the other hand, the 1,3-/1,2-DG isomers ratio is useful for assessing the genuineness of virgin olive oils with low acidities during the early stages of storage.  相似文献   

14.
Anthocyanins (Anths) in olive (Olea europaea L.) fruits at different degrees of pigmentation were assessed nondestructively by measuring chlorophyll fluorescence (ChlF). The method is based on the comparison of the ChlF excitation spectra from olives with different pigmentation from green to green-red, reddish-purple, and purple. The logarithm of the ratio between the fluorescence excitation spectra (logFER) from two different colored zones gave the difference in the absorption spectrum between them. The absorbance spectrum derived from the logFER between a red olive and the same olive devoid of the skin showed the typical Anth green band (at 550 nm). It matched that recorded by microspectrophotometry on a single pulp cell and the in vitro absorbance spectrum of the olive skin extract. As expected, the in vivo Anths absorption maximum increased in intensity going from less to more mature olives and was higher in the sun-exposed olive side with respect to the sun-shaded side. Absolute quantitative nondestructive determination of Anths for each olive sample was obtained by the logFER calculated for two excitation wavelengths, 550 and 625 nm, of ChlF at 740 nm. Going from green to purple skin colors, the Log[ChlF(625)/ChlF(550)] was fairly well-correlated to the extract Anths concentration. Finally, the relationship between the Anths and the other main phenolics present in the olives analyzed by high-performance liquid chromatography was evaluated. The main result was a net increase of verbascoside with increasing Anths content. On the basis of our results, the development of a new rapid and noninvasive method for the monitoring of olive development and ripening can be envisaged.  相似文献   

15.
The behavior in the field and the transfer from olives to olive oil during the technological process of imidacloprid, thiacloprid, and spinosad were studied. The extraction method used was effective in extracting the analytes of interest, and no interfering peaks were detected in the chromatogram. The residue levels found in olives after treatment were 0.14, 0.04, and 0.30 mg/kg for imidacloprid, thiacloprid, and spinosad, respectively, far below the maximum residue levels (MRLs) set for these insecticides in EU. At the preharvest interval (PHI), no residue was detected for imidacloprid and thiacloprid, while spinosad showed a residue level of 0.04 mg/kg. The study of the effect of the technological process on pesticide transfer in olive oil showed that these insecticides tend to remain in the olive cake. The LC/DAD/ESI/MS method showed good performance with adequate recoveries ranging from 80 to 119% and good method limits of quantitation (LOQs) and of determination (LODs). No matrix effect was detected.  相似文献   

16.
'Frantoio' olive fruits were stored at low temperature (4 +/- 2 degrees C) for 3 weeks to investigate the effect of postharvest fruit storage on virgin olive oil quality. Volatile compounds and phenolic compounds explained the changes in sensory quality that could not be explained with quality indices (FFA, PV, K232, and K270). Increases in concentrations of ( E)-2-hexenal and hexanal corresponded to positive sensory quality, whereas increases in ( E)-2-hexenol and (+)-acetoxypinoresinol were associated with negative sensory quality. Volatile and phenolic compounds were also indicative of the period of low-temperature fruit storage. Oleuropein and ligstroside derivatives in olive oil decreased with respect to storage time, and their significant ( p < 0.05) change corresponded to changes in bitterness and pungency. ( Z)-2-Penten-1-ol increased during low-temperature fruit storage, whereas 2-pentylfuran decreased. Changes in volatile compounds, phenolic compounds, quality indices, and sensory notes indicated that virgin olive oil quality was lost within the first week of low-temperature fruit storage and regained at 2 weeks. This research suggests that low-temperature olive fruit storage may be beneficial, with a possibility of increasing oil yield and moderating the sensory quality of virgin olive oils. This study demonstrates that deeper insights into virgin olive oil quality changes during low-temperature fruit storage may be gained by studying volatile and phenolic compounds in addition to quality indices and physical appearance of the fruit.  相似文献   

17.
The aim of this work was to determine the transfer of the chloroplast pigment fractions during the virgin olive oil extraction process, in relation to different factors: the ripening stage of the olive fruits, the irrigation water applied to the olive tree, and the addition of natural microtalc (NMT) during the oil extraction process. Results showed that the percentage of chloroplast pigments transferred from the olive paste to the oil increases with the ripening of the olive fruit (raw material). An excess of the water irrigation applied to the olive tree shows a reduction in the biosynthesis of chloroplast pigments in olive fruits, which is reflected in a low concentration in the virgin oils. Furthermore, the percentage of pigment transfer from the olive paste to the oil during the extraction process is reduced by irrigation, mainly of the chlorophyll fraction. The addition of NMT during the malaxation step produced an increase in the percentage of the total pigments transferred from the olive paste to the oil, in relation to nonaddition.  相似文献   

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

19.
The partition coefficient (K(p)) of the natural phenolic antioxidant compounds in the olive fruit between aqueous and olive oil phases was determined. The antioxidants of olive oil are either present in the olive fruit or formed during the olive oil extraction process. The antioxidants impart stability to and determine properties of the oil and are valuable from the nutritional point of view. The olive oil antioxidants are amphiphilic in nature and are more soluble in the water than in the oil phase. Consequently, a large amount of the antioxidants is lost with the wastewater during processing. The determination of antioxidants was performed using HPLC, and the K(p) was estimated to be from as low as 0.0006 for oleuropein to a maximum of 1.5 for 3,4-DHPEA-EA (di-hydroxy-phenyl-ethanol-elenolic acid, oleuropein aglycon). Henry's law fitted very well to the experimental data. The partition coefficients were also estimated by applying the activity coefficients of the antioxidants in the two phases using a predictive group contribution method, the UNIFAC equation. The K(p) values estimated with UNIFAC method were of the same order of magnitude but varied from the experimental values. Nevertheless, this method may be a rough predictive tool for process optimization or design. Because the K(p) values were very low, some changes in the process are recommended in order to achieve a higher concentration of antioxidants in the oil. A temperature increase may lead to increasing the partition coefficient. Also, limiting the quantity of water during oil extraction could be a basis for designing alternative processes for increasing the antioxidant concentration in the olive oil.  相似文献   

20.
In olive fruits of the cultivar Arbequina, the chlorophyll pigments decrease significantly throughout ripening, while the carotenoids decrease more gradually and discontinuously. There is no degradation of the carotenoid fraction in stages before complete ripeness. The presence of esterified xanthophylls exclusively in this variety suggests that the chloroplast pigment metabolism is different from that in other olive varieties studied previously. There are increases of specific carotenoids, violaxanthin, neoxanthin, antheraxanthin, lutein epoxide, and esterified xanthophylls between the light green and yellowish green ripening stages. Such increases are related to the detection of precursor carotenoids (phytofluene and xi-carotene) in the yellowish green stage. Chlorophyllides (a and b) and alpha-carotene have also been detected exclusively in this variety. Quantitatively, the drastic change in color between light green and yellowish green ripening stages characteristic of this variety can be explained by the considerable reduction found in the chlorophylls/carotenoids ratio. The study of the pigments present in skin and pulp has shown that the pattern of carotenoid distribution differs depending on the fruit part concerned.  相似文献   

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