共查询到20条相似文献,搜索用时 31 毫秒
1.
M. Andjelkovic S. Acun V. Van Hoed R. Verhé J. Van Camp 《Journal of the American Oil Chemists' Society》2009,86(2):135-140
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
2.
F. Dionisi J. Prodolliet E. Tagliaferri 《Journal of the American Oil Chemists' Society》1995,72(12):1505-1511
A method involving reversed-phase high-performance liquid chromatography with amperometric detection has been developed for
the analysis of tocopherols and tocotrienols in vegetable oils. The sample preparation avoids saponification. Recoveries of
α-tocotrienol and γ-tocotrienol in extra virgin olive oil were 97.0 and 102.0%, respectively. No tocotrienols were detected
in olive, hazelnut, sunflower, and soybean oils, whether virgin or refined. However, relatively high levels of tocotrienols
were found in palm and grapeseed oils. This method could detect small quantities (1–2%) of palm and grapeseed oils in olive
oil or in any tocotrienol-free vegetable oil and might, therefore, help assess authenticity of vegetable oils. 相似文献
3.
Ana-Marija Jergović Željka Peršurić Lara Saftić Sandra Kraljević Pavelić 《Journal of the American Oil Chemists' Society》2017,94(6):749-757
Adulteration of extra virgin olive oil (EVOO) by addition of other vegetable oils or lower-grade olive oils is a common problem of the oil market worldwide. Therefore, we developed a fast protocol for detection of EVOO adulteration by mass spectrometry fingerprinting of triacylglycerol (TAG) profiles based on MALDI-TOF/MS. For that purpose, EVOO TAG profiles were compared with those of edible sunflower oil and olive oil composed of refined olive oil and virgin olive oils. Adulteration of EVOO was simulated by addition of sunflower and mixture of refined olive oil and virgin olive oils at 1, 10 and 20% w/w. Results of mass spectrometry TAG profiling were compared with routinely assessed K values for identification of adulteration. MALDI-TOF/MS technology coupled with statistical analysis was proven as useful for detection of adulteration in EVOO at a rate down to 1%. In contrast, standard spectrophotometric methods failed to identify minor adulterations. In addition, the ability of MALDI-TOF/MS in detection of adulteration was tested on EVOO samples from different geographical regions. Results demonstrated that MALDI-TOF/MS technology coupled with statistical analysis is able to distinguish adulterated oils from other EVOO. 相似文献
4.
L. Di Giovacchino M. R. Mucciarella N. Costantini M. L. Ferrante G. Surricchio 《Journal of the American Oil Chemists' Society》2002,79(4):339-344
Experiments were carried out to study the possibility of improving the stability of extra virgin olive oil by using nitrogen
as a conditioner gas during storage. With this aim, virgin olive oil samples, obtained from Leccino and Coratina cultivars,
were stored in the dark, in closed bottles conditioned with air or nitrogen at 12–20 and 40°C. Results indicated that the
FFA percentage increased over 1% only when oils were stored at 40°C. The PV and the K
232 value (light absorbance at 232 nm) of oils increased over the limit value allowed by European Union law when the bottles
were only partly filled and air was the conditioner gas. The use of nitrogen as conditioner gas helped to avoid this risk
during 24 mon of storage at 12–20°C. The total phenolic content of both cultivars oils decreased during storage because their
oxidation protected the oils from autoxidation. The content of total volatile compounds in oils decreased continuously during
storage at 12–20°C, whereas it increased over 10 (Coratina cv.) and 15 (Leccino cv.) mon and then diminished when the storage
temperature was 40°C. The same behavior, i.e., increase then decrease, was ascertained for trans-2-hexenal. The hexanal content of oils increased continuously during storage because this compound is formed by the decomposition
of the 13-hydroperoxide of linoleic acid. 相似文献
5.
Francisco J. Hidalgo Manuel Alaiz Rosario Zamora 《Journal of the American Oil Chemists' Society》2002,79(7):685-689
Twenty-eight virgin olive oils—from different regions of Spain and prepared from olive drupes of different varieties—and six
refined olive oils were analyzed to determine the presence of proteins in these oils. All oils studied showed the presence
of proteins in the range of 7–51 μ/100 g of oil. There were no significant differences in protein content in oils from different
varieties or between virgin or refined oils. In addition, all oils exhibited analogous amino acid patterns, suggesting a similarity
among protein fractions obtained from different oils. A polypeptide with an apparent M.W. of 4600 Da was common to the isolated
protein fractions. These results suggest that this polypeptide is a previously unknown minor component in olive oils. No clear
influence of this component on oil stability was observed when oil stabilities were estimated as a function of phenol, tocopherol,
phosphorus, and protein contents of the oils. 相似文献
6.
Oroncio Jiménez de Blas Amando del Valle González 《Journal of the American Oil Chemists' Society》1996,73(12):1685-1689
Compositional analysis of the sterol fraction of olive oil can be used to assess the degree of purity of the oil and the absence
of admixture with other plant oils. This determination also permits characterization of the type of olive oil in question:
virgin, refined, or solvent-extracted. In the present work, 130 samples of olive oil were analyzed, the sterol fractions were
separated from the unsaponifiable fraction by silica gel plate chromatography, and later they were analyzed as the trimethylsilyl
ether derivatives by capillary column gas chromatography. From the results obtained, it was concluded that this methodology
is able to differentiate among virgin, refined, and solvent-extracted olive oils. Stigmasterol, clerosterol, Δ5-avenasterol,
Δ7-stigmasterol, and Δ7-avenasterol permit the differentiation of the three types of oil from one another. Campesterol, Δ5,
23-stigmastadienol, β-sitosterol, and Δ5,24-stigmastadienol permit the differentiation of only two oils from each other but
confirm the conclusions obtained for other sterols. Correlations between the different sterols of virgin, refined, and solven-extracted
olive oil also have been obtained. 相似文献
7.
Use of high-resolution 13C nuclear magnetic resonance spectroscopy for the screening of virgin olive oils 总被引:2,自引:0,他引:2
Rosario Zamora Virginia Alba Francisco J. Hidalgo 《Journal of the American Oil Chemists' Society》2001,78(1):89-94
13C Nuclear magnetic resonance (NMR) spectra of 104 oil samples were obtained and analyzed in order to study the use of this
technique for routine screening of virgin olive oils. The oils studied included the following: virgin olive oils from different
cultivars and regions of Europe and north Africa, and refined olive, “lampante” olive, refined olive pomace, high-oleic sunflower,
hazelnut, sunflower, corn, soybean, rapeseed, grapeseed, and peanut oils, as well as mixtures of virgin olive oils from different
geographical origins and mixtures of 5–50% hazelnut oil in virgin olive oil. The analysis of the spectra allowed us to distinguish
among virgin olive oils, oils with a high content of oleic acid, and oils with a high content of linoleic acid, by using stepwise
discriminant analysis. This parametric method gave 97.1% correct validated classifications for the oils. In addition, it classified
correctly all the hazelnut oil samples and the mixtures of hazelnut oil in virgin olive oil assayed. All of these results
suggested that 13C NMR may be used satisfactorily for discriminating some specific groups of oils, but to obtain 100% correct classifications
for the different oils and mixtures, more information than that obtained from the direct spectra of the oils is needed. 相似文献
8.
Christian Gertz Bertrand Matthus Ina Willenberg 《European Journal of Lipid Science and Technology》2020,122(6)
The European Parliament identifies virgin olive oil (VOO) as one of the foods which are often subject to fraudulent activities. Possibilities of adulteration are the application of illegal soft deodorization of extra virgin olive oil (EVOO) or the commercialization of blends of EVOO with soft‐deodorized EVOO or refined vegetable oils. Despite the search for possibilities to prove the illegal soft deodorization of EVOO or the addition of cheaper vegetable oils to EVOO, suitable methods are still missing. Therefore, the aim of the study is to develop a new analytical and statistical approach addressing detection of mild deodorization or addition of refined foreign oils. For this purpose, VOOs are treated in lab‐scale for 1 h up to 28 days at different temperatures (20, 50, 60, 80,100, 110, and 170 °C) in order to simulate and study the effect of heat treatment on known analytical parameters by near infrared spectroscopy (NIR). A logit regression model enabling the calculation of the probability for a heat treatment is developed. This new methodology allows detecting both soft deodorized olive oils and blends of EVOO with cheaper full refined vegetable oils. Adding only 10% of full refined oil could be detected in extra VOO. Practical Applications: NIR methods combined with chemometrics have become one of the most attractive analytical tools to control quality of food. It is a simple, precise, and rapid method. All relevant analytical parameters of oxidative and thermal fat degradation can be determined in a single run and be used to detect adulterated virgin olive oils (VOOs). The use of a simple equation developed from the logistic regression using peroxide value, K‐values, p‐anisidine value, pyropheophytine, 1,2‐diacylglycerols, total polar compounds and monomeric oxidized triacylglycerols, and other well‐known parameters allows to detect mild deodorized olive oils or also blends of VOO with soft‐deodorized ones or the addition of low amounts of foreign vegetable oils. This technique has potential to be used as a screening method for the detection of adulterated olive oils using both the traditional laboratory methods and the corresponding NIR‐methods. 相似文献
9.
M. Melgosa L. Gómez-Robledo R. Huertas L. F. Capitán-Vallvey M. J. Moyano F. J. Heredia 《Journal of the American Oil Chemists' Society》2009,86(7):627-636
Color measurements have been performed using eighteen virgin-olive-oil tasting cups with ten different commercial virgin olive
oils, positioned in a color cabinet with a D65 source. Three geometries (spectroradiometer tilted 0°, 30°, and 60°) were employed,
simulating different positions of the taster’s eye. Our main goal was to test whether traditional blue-tinted cups effectively
conceal the color of virgin olive oils, as desired in sensorial analyses. None of the cups employed had all their geometrical
dimensions within the standardized values, despite being cups used in official sensorial analyses. Measuring a magnitude similar
to the spectral transmittance, we found substantial differences among the glasses of the eighteen tasting cups. Comparing
color variability for one virgin olive oil in different tasting cups, and one tasting cup with different virgin olive oils,
we discovered that: (1) variability was higher in the case of one virgin olive oil in different cups; (2) in both cases the
variability increased with the tilt of the spectroradiometer; (3) even when the variability was lowest (i.e., 0° measurements
for two oils in the same cup), the average color difference was above typical visual thresholds in simultaneous comparison
experiments. In the most usual case of a successive comparison between two oils in the same tasting cup, it is expected that
in most cases tasters will perceive color differences between the oils when their eyes are tilted 60° with respect to the
horizontal, but not when they observe the cup in the horizontal direction. In summary, blue-tinted olive-oil-tasting cups
reduce, but do not completely conceal, oil color. The use of opaque tasting cups with black walls is suggested. 相似文献
10.
The adulteration of extra virgin olive oil with cheaper oils is a major problem in the olive oil market. In this study, near-infrared,
mid-infrared, and Raman spectroscopic techniques were used to quantify the amount of olive pomace oil adulteration in extra
virgin olive oil. The concentration of olive pomace oil in extra virgin olive oil was in the range between 0 and 100% in 5%
increments by weight. Of the methods studied, Fourier transform-Raman spectroscopy gave the highest correlation with a correlation
coefficient of 0.997 and a standard error of prediction of 1.72%. The spectroscopic techniques have the potential to become
a tool for rapid determination of adulteration in extra virgin olive oil, because they are casy to use and cost-effective. 相似文献
11.
13C NMR spectra of oil fractions obtained chromatographically from 109 vegetable oils were obtained and analyzed to evaluate
the potential use of those fractions in the classification of vegetable oils and to compare the results with the NMR analysis
of complete oils. The oils included the following: virgin olive oils from different cultivars and regions of Europe and north
Africa; “lampante” olive, refined olive, refined olive pomace, hazelnut, rapeseed, high-oleic sunflower, corn, grapeseed,
soybean, and sunflower oils; and mixtures of virgin olive oils from different geographical origins. Oils were divided into
two sets of samples. The training set (98 samples) was employed to select the variables that resulted in significant discrimination
among the different oil classes. By using stepwise discriminant analysis, more than 98% of correct validated assignments were
obtained; these results were confirmed when applied to the test set (11 blind samples). Results suggest that the use of oil
fractions considerably increases the discriminating power of NMR in the analysis of vegetable oils. 相似文献
12.
Effect of natural antioxidants in virgin olive oil on oxidative stability of refined,bleached, and deodorized olive oil 总被引:1,自引:0,他引:1
M. Teresa Satue Shu-Wen Huang Edwin N. Frankel 《Journal of the American Oil Chemists' Society》1995,72(10):1131-1137
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
13.
I. J. Wesley F. Pacheco A. E. J. McGill 《Journal of the American Oil Chemists' Society》1996,73(4):515-518
The application of discriminant analysis for identifying and quantifying adulterants in extra virgin olive oils is presented.
Three adulterants were used (sunflower oil, rapessed oil, and soybean oil) and were present in the range 5–95%. Near-infrared
spectroscopy and principal components analysis were used to develop a discriminant analysis equation that could identify correctly
the type of seed oil present in extra virgin olive oil in 90% of cases. Partial least squares analysis was used to develop
a calibration equation that could predict the level of adulteration. Cross validation suggested that it was possible to measure
the level of adulteration to an accuracy of ±0.9%. External validation of the derived calibation equation gave a standard
error of performance of ±2.77%. 相似文献
14.
Michael H. Gordon Christopher Covell Nicole Kirsch 《Journal of the American Oil Chemists' Society》2001,78(6):621-624
Analysis of the polar fraction from virgin olive oil and pressed hazelnut oil by high-performance liquid chromatography showed
marked differences in the chromatograms of the polar components in the two oils. Six commercial samples of pressed hazelnut
oil and 12 samples of virgin olive oil (or blended olive oil including virgin olive oil) were analyzed. The phenolic content
of the pressed hazelnut oil samples was 161±6 mg·kg−1. Inspection of the chromatograms showed that the pressed hazelnut oil extracts contained a component that eluted in a region
of the chromatogram that was clear in the olive oil samples, and consequently this component could be used to detect adulteration
of virgin olive oil by pressed hazelnut oil. The component had a relative retention time of 0.9 relative to 4-hydroxybenzoic
acid added to the oil as an internal standard. The ultraviolet spectrum of the component showed a maximum at 293.8 nm, but
the component could not be identified. Analysis of blends of oils showed that adulteration of virgin olive oil by commercial
pressed hazelnut oil could be detected at a level of about 2.5%. 相似文献
15.
Anna Dankowska Maria Małecka 《European Journal of Lipid Science and Technology》2009,111(12):1233-1239
The potential of fluorescence spectroscopy for detecting adulteration of extra virgin olive oil with olive oil was investigated. Synchronous fluorescence spectra were collected in the region of 240–700 nm with wavelength intervals (Δλ) of 10, 30, 60 and 80 nm. Regression models were used to quantify the detection limits of adulteration. The technique applied proved to be useful for detecting the addition of olive oil to extra virgin olive oil. The lowest detection limits of adulteration (8.9% and 8.4%) were observed when the wavelength interval applied were 60 and 80 nm, respectively. 相似文献
16.
Mohamed Bouaziz Ines Feki Mohamed Ayadi Hedya Jemai Sami Sayadi 《European Journal of Lipid Science and Technology》2010,112(8):894-905
Refined olive oil and olive‐pomace oil were enriched with olive leaf phenolic compounds in order to enhance its quality and bring it closer to virgin olive oil. The changes that occurred in the concentrations of pure oleuropein, oleuropein aglycone, hydroxytyrosol acetyl and α‐tocopherol at 400 µg/kg of oil during the storage of refined olive oil and olive‐pomace oil under accelerated conditions (50 °C) were investigated. In a period of 4 months, α‐tocopherol decomposed by 75% whereas less than 40% of the phenols were lost. During storage, enzymatic olive leaf extract hydrolysate that contains two major compounds, hydroxytyrosol and oleuropein aglycone showed the highest antioxidant activity and the lowest detected stability, followed by oleuropein. The oleuropein in olive leaf extracts exhibited similar degradation profiles, reducing by 60–50% and 80% for the olive oil and olive‐pomace oil in 6 months, respectively. The acetylated extract, however, displayed a loss of 10 and 5% in olive oil and olive‐pomace oil, respectively. In the fatty acid composition, an increase in oleic acid and a decrease in linoleic acid were observed. The antiradical activities of the olive oil and olive‐pomace oil enriched with olive leaf phenolic compounds at 400 ppm showed that enzymatic hydrolysate extract had the highest protective effect against oil oxidation. Based on the Rancimat method, the oils with added leaf enzymatic hydrolysate extract had the lowest peroxide value and the highest stability. After 6 months of storage and at 120 °C, the oxidative resistance of refined olive oil and olive‐pomace oil reached 0.71 and 0.89 h, respectively, whereas that of the non‐enriched samples fell to zero. 相似文献
17.
Rosario Zamora Gemma Gómez M. Carmen Dobarganes Francisco J. Hidalgo 《Journal of the American Oil Chemists' Society》2002,79(3):261-266
One hundred nine oil samples were separated chromatographically to obtain oil fractions with a decreased TAG content but with
enhanced levels of the minor components that define oil genuineness and quality. The oils, which included virgin olive oils
from different cultivars and regions of Europe and north Africa and refined olive, “lampante” olive, refined olive pomace,
hazelnut, rapeseed, high-oleic sunflower, corn, grapeseed, soybean, and sunflower oils, were fractionated on a silica gel
column with hexane/diethyl ether as the mobile phase eluent. The method was highly reproducible, and the fraction obtained
contained about 15% unmodified TAG and 85% polar compounds, which included polymeric TAG, oxidized TAG, DAG, MAG, and FFA,
in addition to other minor polar components of the oils. The presence of these compounds, in an enriched fraction, should
provide information about the thermal, oxidative, and hydrolytic alterations of the oils, as well as many compounds of interest
in determining oil genuineness. The results indicate that these fractions can provide more information than the original oils
for NMR or other spectroscopic studies used in the determination of oil quality. 相似文献
18.
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. 相似文献
19.
Reports on the methylsterol fractions of hazelnut oils are scarce. The objectives of this study were to characterize methylsterols
in hazelnut and virgin olive oils and to study the possibility of detection of adulteration of virgin olive oils. In hazelnut
oils, 4-desmethylsterols were present in higher proportions (86 to 91%) than in virgin olive oils where this fraction was
ca. 50% of the total sterol. In the 4-monomethylsterol fraction, citrostadienol was the major component in both kinds of oils
followed by cycloeucalenol and obtusifoliol in virgin olive oils, and obtusifoliol in hazelnut oils. 24-Methylenecycloartanol
was predominant in both kinds of oils in the 4,4′-dimethylsterols. For the first time, δ-amyrin was tentatively identified
by comparing published mass spectral data in the analyzed samples of both kinds of oils. An unknown compound X (containing
a lupane skeleton) and lupeol were detected only in the 4,4′-dimethylsterols fraction of hazelnut oils at a level of 2–8 and
6–10%, respectively. GC-MS analysis showed that adulteration of virgin olive oil by hazelnut oil could be detected at a level
less than 4% by using these two compounds as possible potential markers. 相似文献
20.
The triterpene alcohol fraction in several virgin olive oils and the corresponding oils refined by alkali and by physical
processes was analyzed by gas chromatography. A Δ7 compound was detected in all refined olive oils but not in virgin olive oils. This compound was tentatively identified by
gas chromatography-mass spectrometry as 24-methyl-5α-lanosta-7,24-dien-3β-ol, a 24-methylenecycloartanol isomer produced during
the refining process by the opening of the 9, 19 cyclopropane ring with formation of a double bond in the Δ7 position and the translocation of a double bond in the side chain from the 24–28 to the 24–25 position. 相似文献