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1.
A method using high-performance liquid chromatography and fluorescence detection is optimized and validated for the determination
of Dowtherm ATM in spiked oleochemicals and edible oils. The samples are directly injected into a reversed-phase C18 column, and Dowtherm
A is detected using a fluorescence detector set at 247 nm excitation and 310 nm emission wavelengths. The simple isocratic
mobile phase used is a mixture of methanol and water (90∶10, vol/vol) at a flow rate of 1 mL/min. The limits of quantitation
are from 0.1 to 0.2 μg/g. Mean recoveries ranged from 93.0 to 116% with reproducibilities of 1.29–3.84%. The procedure provides
a simple, reliable and sensitive method for determining Dowtherm A residue in oleochemicals and edible oils without prior
sample cleanup or extraction. 相似文献
2.
An HPLC method for the determination of partially hydrogenated terphenyls-based thermal heating fluid, Therminol 66™, in various vegetable oils is described. Direct analysis of palm olein showed that the 3- and 4-cyclohexylbiphenyl peaks
of the Therminol 66™ used in quantitative analysis co-eluted with other fluorescent peaks present naturally in the oil. However, those interfering
peaks were readily removed after saponification of palm olein. The concentrations of the 3- and 4-cyclohexylbiphenyls of Therminol
66™ were monitored by fluorescence detection at 257 (excitation) and 320 nm (emission). The calibration graph obtained by using
the peak areas of the 3- and 4-cyclohexylbiphenyls against the concentrations of Therminol 66™ was linear, with a correlation coefficient of 0.994. The limit of quantitation, using spiked palm olein, was as low as 0.2
μg/g. The coefficients of variation obtained from the intra- and interday studies obtained by using three spiked concentrations
(0.2, 0.5, and 1.0 μg/g) were 1.76–6.43 and 3.77–10.4%, respectively. The mean recovery value obtained from sunflower, soybean,
and canola oils was more than 88.7%. 相似文献
3.
Edible oils such as coconut, groundnut, hydrogenated vegetable, linseed, mustard, olive, palm, refined vegetable, rice bran,
safflower, sesame, soybean, and sunflower were analyzed for the presence of light and heavy polycyclic aromatic hydrocarbon
(PAH) residues using liquid-liquid extraction, cleanup on a silica gel column, and resolution and determination by HPLC using
a fluorescence detector. Ten PAH viz. acenaphthene, anthracene, benzo(a)pyrene, benzo(e)pyrene, benz(ghi)perylene, chrysene,
coronene, cyclopenta(def)phenanthrene, phenanthrene, and pyrene were monitored. Analysis of 296 oil samples showed that 88.5%
(262) samples were contaminated with different PAH. Of 262 contaminated edible oil samples, 66.4% of the samples showed PAH
content of more than the 25 μg/kg recommended by the German Society for Fat Science. The total PAH content was highest in
virgin olive oil (624 μg/kg) and lowest in refined vegetable oils (40.2 μg/kg). The maximum content (265 μg/kg) of heavy PAH
was found in olive oil and the minimum (4.6 μg/kg) in rice bran oil. Phenanthrene was present in 58.3% of the oil samples
analyzed, followed by anthracene (53%). Among the heavy PAH, benzo(e)pyrene was observed in 31.2% of the samples followed
by benzo(a)pyrene (25.5%). The intake of PAH was highest through olive oil (20.8 μg/day) followed by soybean oil (5.0 μg/day)
and lowest through refined vegetable oil (1.3 μg/day). Based on these monitoring studies, international and national guidelines
for permissible levels of PAH can be prepared so as to restrict the intake of these toxic contaminants. 相似文献
4.
Frying Quality Characteristics of French Fries Prepared in Refined Olive Oil and Palm Olein 总被引:2,自引:0,他引:2
Elham Tabee Margaretha Jägerstad Paresh C. Dutta 《Journal of the American Oil Chemists' Society》2009,86(9):885-893
The objective of this study was to compare two oils with different polyunsaturated/saturated (P/S) fatty acid ratios, refined
olive oil (P/S 0.75) and palm olein (P/S 0.25), in frying French fries. The chemical qualities of the oil residues extracted
from the French fries were assayed for five consecutive batches fried at 1-h intervals. The levels of total polar compounds,
free fatty acids, p-anisidine value and phytosterol oxidation products (POPs) were elevated in French fries fried in both oils. The level of total
polar compounds increased from 4.6 in fresh refined olive oil to 7.3% in final batches of French fries. The corresponding
figures for palm olein were 9.8–13.8%. The level of free fatty acid in fresh refined olive oil increased from 0.06 to 0.11%
in final products. These figures for palm olein were 0.04–0.13%. The p-anisidine value increased from 3.7 to 32.8 and 2.5 to 53.4 in fresh oils and in final batches of French fries in refined
olive oil and palm olein, respectively. The total amount of POPs in fresh refined olive oil increased from 5.1 to 9.6 μg/g
oil in final products. These figures were 1.9 to 5.3 μg/g oil for palm olein. 相似文献
5.
Felib Y. Iskander 《Journal of the American Oil Chemists' Society》1993,70(8):803-805
Instrumental neutron activation analysis was used to determine the concentration of As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hg, K,
Na, Rb, Sb, Sc, Se, Sr and Zn in almond, sunflower, peanut, sesame, linseed, soy, corn and olive oils, as well as in three
margarine brands. The concentration of As, Ba, Ce, Cs, Eu, Hg, Rb, Se and Sr were below the system detection limit under the
experiment conditions. Chromium was detected only in one of the margarine samples (171 μg/g); Sb only in corn oil (18 ng/g)
and Sc only in linseed oil (19 ng/g). Cobalt, Fe, K, Na and Zn were detected in all oil and margarine samples investigated.
The concentration ranges for Co, Fe, K, Na and Zn in oils were: 0.016–0.053; 4.45–19.1; 5.93–47.2; 2.44–12.9 and 0.48–1.54
μg/g, respectively. For margarine, the concentration ranges for Co, Fe, K, Na and Zn were 0.09–0.012; 4.53–10.6; 58.3–1140;
13.2–9870 and 0.38–0.47 μg/g, respectively. The elemental contents of the analyzed samples are within the ranges reported
in the literature for edible oils and fats. 相似文献
6.
Analysis of free and esterified sterols in vegetable oils 总被引:2,自引:6,他引:2
T. Verleyen M. Forcades R. Verhe K. Dewettinck A. Huyghebaert W. De Greyt 《Journal of the American Oil Chemists' Society》2002,79(2):117-122
In vegetable oils, phytosterols occur as free sterols or as steryl esters. Few analytical methods report the quantification
of esterified and free sterols in vegetable oils. In this study, esterified and free sterols were separated by silica gel
column chromatography upon elution with n-hexane/ethyl acetate (90∶10 vol/vol) followed by n-hexane/diethyl ether/ethanol (25∶25∶50 by vol). Both fractions were saponified separately and the phytosterol content was
quantified by GC. The analytical method for the analysis of esterified and free sterols had a relative standard deviation
of 1.16% and an accuracy of 93.6–94.1%, which was comparable to the reference method for the total sterol analysis. A large
variation in the content and distribution of the sterol fraction between different vegetable oils can be observed. Corn and
rapeseed oils were very rich in phytosterols, which mainly occurred as steryl esters (56–60%), whereas the majority of the
other vegetable oils (soybean, sunflower, palm oil, etc.) contained a much lower esterified sterol content (25–40%). No difference
in the relative proportion of the individual sterols among crude and refined vegetable oils was observed. 相似文献
7.
The concentrations of arsenic, selenium, iodine and bromine in a series of fish, plant and mammalian oils have been determined
by cyclic instrumental neutron activation analysis (CINAA). Crude fish oils contain between 0.047 and 0.151 μg Se g−1, 2.36–14.5 μg As g−1, 2.36–9.63 μg Br g−1 and 0.97–4.76 μgI g−1. Seal oil contains the same four elements, but at levels below the lower end of the fish oil ranges. Iodine, bromine and
arsenic were not detected in rape-seed or soybean oils and the concentration of selenium varied from < 0.010 to 0.042 μg g−1. The levels of selenium, iodine and bromine are reduced markedly by hydrogenation of the menhaden oils. The CINAA method
yielded results which were in agreement with pub-lished values obtained by other methods. The technique was rapid, requiring
minimal sample manipulation, and was essentially free from interferences. 相似文献
8.
Temperature effect on the viscosities of palm oil and coconut oil blended with diesel oil 总被引:1,自引:0,他引:1
One of the major difficulties in using crude vegetable oils as substitute fuels in diesel engines is their relatively high
viscosities. Increasing the temperature of the crude vegetable oil, blending it with diesel oil, or the combination of both
offers a simple and effective means of controlling and lowering the viscosities of vegetable oils. This work reports viscosity
data, determined with a rotational bob-and-cup viscometer, for crude palm oil and cononut oil blended with diesel oil over
the temperature range of 20–80°C and for different mixture compositions. All the test oil samples showed a time-independent
newtonian type of flow behavior. The reduction of viscosity with increasing liquid temperature followed an exponential relationship,
with the two constants of the equation being a function of the volume percentage of the vegetable oil in the mixture. A single
empirical equation was developed for predicting the viscosity of these fuel mixtures under varying temperatures and blend
compositions. 相似文献
9.
In the present study we have used statistical experimental design and multivariate optimization to formally optimize a reversed-phase
high-performance liquid chromatography method for the analysis of triacylglycerol molecular species of natural oils. The optimal
conditions found were, on an octadecylsilan-column, from acetonitrile/isooctane (90∶10, vol/vol) to acetonitrile/ethanol/isooctane
(40∶35∶25, by vol), at a column temperature of 50°C and a flowrate of 1.5mL/min using a negative exponential gradient profile.
Several examples of separations of natural seed and animal oils,i.e., soybean oil, rapeseed oil, palm oil, linseed oil, tallow and fish oil, are given. A version of the equivalent carbon number
concept, utilizing the Snyder polarity index, was used to identity the molecular species. 相似文献
10.
Antioxidant capacity of extra-virgin olive oils 总被引:1,自引:1,他引:0
Paolino Ninfali Gianfranca Aluigi Mara Bacchiocca Mauro Magnani 《Journal of the American Oil Chemists' Society》2001,78(3):243-247
In this study, the oxygen radical absorbance capacity (ORAC) of vegetable oils was investigated using a spectrofluorometric
method, which measures the protection of the phenolic substances of the oil on the β-phycoerythrin fluorescence decay in comparison
with Trolox. More than 97% of the phenolic substances was extracted from the oil using methanol, and the methanolic extract
was then used for the ORAC and the total phenolics assay. We found a significant correlation between ORAC values of different
olive oils and the total amount of phenolics. For extra-virgin olive oils, maximal ORAC values reached 6.20±0.31 μmol Trolox
equivalent/g, while refined and seed oils showed values in the 1–1.5 μmol Trolox equivalent/g range. Our method is useful
to assess the quality of olive oils and to predict, in combination with the rancidity tests, their stability against oxidation. 相似文献
11.
Sajid Husain M. Kifayatullah G. S. R. Sastry N. Prasada Raju 《Journal of the American Oil Chemists' Society》1993,70(12):1251-1254
Application of13C nuclear magnetic resonance (NMR) spectroscopy for detection of castor oil (CO) in various edible oils, such as coconut oil,
palm oil, groundnut oil and mustard oil, is described. Characteristic signals observed at δ 132.4, δ 125.6, δ 71.3, δ 36.8
and δ 35.4 ppm, due to C10, C9, C12, C13 and C11 carbons of ricinoleic acid (RA) in CO, were selected for distinguishing it
from edible oils. Quantitative13C NMR spectra of oils were recorded in CDCl3 with a gated decoupling technique. The minimum detection limits for qualitative and quantitative analyses were 2.0 and 3.0%,
respectively. The proposed method is simple, nondestructive and requires no sample pretreatment. Its application to heat-abused
oils has also been demonstrated successfully without any of the interferences observed in most other methods. 相似文献
12.
Tocol-derived minor constituents in selected plant seed oils 总被引:1,自引:2,他引:1
Various crude and processed seed oils were analyzed for tocopherols (T) and tocotrienols (T3) by reversed-phase HPLC with fluorescence detection (FL). The oils included processed canola oil, crude corn oil, crude milkweed
oil, crude palm oil, crude/processed rice bran oils, crude/processed soybean oil, crude/processed sunflower oil, and related
modified oil, crude/processed sunflower oil, and related modified oil varieties. The HPLC system consisted of a pentafluorophenylsilica
(PFPS) column and a mobile phase of methanol and water. The results of comparative methodological studies with rice bran oils
and milkweed oils indicated that the reversed-phase PEPS-HPLC method in conjunction with the use of less hazardous solvents
proved to be superior and a viable alternative to the conventional normal-phase HPLC method. Unlike the traditional nonpolar
octadecylsilica phase, which fails to resolve β-γ pairs of T and T3, HPLC with the unique polar PFPS column enables separations of all compounds of interest. Except for palm oil, βT and γT
were detected in all other crude oils. Although most milkweed oils contained moderale levels of βT and γT, the βT species
was present in relatively low abundance in edible oils despite the observation of fairly high concentrations of γT in the
latter oils. βT3 and γT3 were detected along with αT3 and σT3 only in palm and rice bran oils. Tocolderived antioxidant distribution data for zero-time processed oils provided potential
utility in correlation studies of frying quality and stability. The variable distribution data for crude oils shed some light
on market profitability of oilseeds with rich sources of vitamin E-related minor constituents. 相似文献
13.
O. Yu Berezin Ya I. Tur’yan L. Kogan I. Kuselman A. Shenhar 《Journal of the American Oil Chemists' Society》1997,74(10):1339-1341
A novel pH-metric method is described for the determination of acid values (AV) in vegetable oils without titration. The method
is based on a reagent containing triethanolamine, isopropanol, and water to which an oil sample is added before measuring
pH. Oil samples with AV in the range 0.006–0.107 mg KOH/g oil were prepared from commercial soybean oil by treatment with
a strong-base anion exchanger in OH− form and addition of oleic acid. Compared to the standard titrimetric method, significantly greater AV were obtained at less
then 0.02 mg KOH/g oil. This was due to the influence of triethanolamine hydrolysis on the acid-base equilibrium in the mixture
“oil-reagent.” Thus, the AV 0.02 mg KOH/g oil is accepted as the limit of quantitation. Because refined oils usually have
AV of 0.05 mg KOH/g oil or more, this method should be suitable for practical oil analyses. 相似文献
14.
Stoichiometric determination of hydroperoxides in fats and oils by fourier transform infrared spectroscopy 总被引:1,自引:0,他引:1
K. Ma F. R. van de Voort J. Sedman A. A. Ismail 《Journal of the American Oil Chemists' Society》1997,74(8):897-906
A primary Fourier transform infrared (FTIR) spectroscopic method for the determination of peroxide value (PV) in edible oils
was developed based on the stoichiometric reaction of triphenylphosphine (TPP) with hydroperoxides to produce triphenylphosphine
oxide (TPPO). Accurate quantitation of the TPPO formed in this reaction by measurement of its intense absorption band at 542
cm−1 provides a simple means of determining PV. A calibration was developed with TPPO as the standard; its concentration, expressed
in terms of PV, covered a range of 0–15 PV. The resulting calibration was linear over the analytical range and had a standard
deviation of ±0.05 PV. A standardized analytical protocol was developed, consisting of adding ∼0.2 g of a 33% (w/w) stock
solution of TPP in hexanol to ∼30 g of melted fat or oil, shaking the sample, and scanning it in a 100-μm KCI IR transmission
cell maintained at 80°C. The FTIR spectrometer was programmed in Visual Basic to automate scanning and quantitation, with
the reaction/FTIR analysis taking about 2 min per sample. The method was validated by comparing the analytical results of
the AOCS PV method to those of the automated FTIR procedure by using both oxidized oils and oils spiked with tert-butyl hydroperoxide. The two methods correlated well. The reproducibility of the FTIR method was superior (±0.18) to that
of the standard chemical method (±0.89 PV). The FTIR method is a significant improvement over the standard AOCS method in
terms of analytical time and effort and avoids solvent and reagent disposal problems. Based on its simple stoichiometry, rapid
and complete reaction, and the singular band that characterizes the end product, the TPP/TPPO reaction coupled with a programmable
FTIR spectrometer provides a rapid and efficient means of determining PV that is especially suited for routine quality control
applications in the fats and oils industry. 相似文献
15.
Daniel P. Schwartz Aly H. Rady Soledad Castañeda 《Journal of the American Oil Chemists' Society》1994,71(4):441-444
A fast-food fat (mostly tallow), olive oil and safflower oil were heated in air for 4 d and periodically analyzed for oxofatty
acids (OFA), monohydroxy-fatty acids (HFA) and polyhydroxy-fatty acids (PHFA). After transmethylation, the OFA were estimated
as 2,4-dinitrophenylhydrazones, and the HFA and PHFA were quantitated as pyruvic acid 2,6-dinitrophenylhydrazone esters. At
least half of the maximum concentration attained for OFA, HFA and PHFA was generated between 16–24 h of heating of each oil.
Safflower oil contained greater concentrations of HFA and PHFA than either olive oil or the fast-food fat. The fastfood fat
sample contained a greater concentration of OFA than did the other oils. The sum of the concentrations of OFA, HFA and PHFA
at the time of maximum formation in the oils was approximately 260 μmoles/g at 48–72 h for safflower, 200 μmoles/g at 48–72
h for olive and 170 μmoles/g at 72 h for the fast-food fat.
Presented at the 79th Annual AOCS Meeting, Phoenix, Arizona, May 8–12, 1988. 相似文献
16.
Y. C. Mitei J. C. Ngila S. O. Yeboah L. Wessjohann J. Schmidt 《Journal of the American Oil Chemists' Society》2009,86(7):617-625
The phytosterol, tocopherol, and tocotrienol profiles for mkukubuyo, Sterculia africana, manketti, Ricinodendron rautanenni, mokolwane, Hyphaene petersiana, morama, Tylosema esculentum, and moretologa-kgomo, Ximenia caffra, seed oils from Botswana have been determined. Normal-phase HPLC analysis of the unsaponifiable matter showed that among the
selected oils, the most abundant tocopherol and tocotrienol were γ-tocopherol (2232.99 μg/g) and γ-tocotrienol (246.19 μg/g),
detected in manketti and mkukubuyo, respectively. Mokolwane oil, however, contained the largest total tocotrienol (258.47 μg/g).
Total tocol contents found in manketti, mokolwane, mkukubuyo, morama, and moretologa-kgomo oils were 2238.60, 262.40, 246.20,
199.10, and 128.0 μg/g, respectively. GC–MS determination of the relative percentage composition of phytosterols showed 4-desmethylsterols
as the most abundant phytosterols in the oils, by occurring up to 90% in moretologa-kgomo, mkukubuyo, and manketti seed oils,
with β-sitosterol being the most abundant. Mokolwane seed oil contained the largest percentage composition of 4,4-dimethylsterols
(45.93%). Besides 4-desmethylsterols (75%), morama oil also contained significant amounts of 4,4-dimethylsterols and 4-monomethylsterols
(15.72% total). GC–MS determination of the absolute amounts of 4-desmethylsterols, after SPE fractionation of the unsaponifiable
matter, confirmed that β-sitosterol was the most abundant phytosterol in the test seed oils, with manketti seed oil being
the richest source (1326.74 μg/g). The analysis showed total 4-desmethylsterols content as 1617.41, 1291.88, 861.47, 149.15,
and 109.11 μg/g for manketti, mokolwane, mkukubuyo, morama, and moretologa-kgomo seed oils, respectively. 相似文献
17.
Saba Naz S. T. H. Sherazi Farah N. Talpur M. Younis Talpur Huseyin Kara 《Journal of the American Oil Chemists' Society》2012,89(6):973-977
Deodorizer distillate is an important by-product obtained during deodorization in the edible oil industries. It is a complex mixture of many health beneficial constituents like phytosterols, tocopherols and squalene. In the present study a simple gas chromatographic method with mass spectrometry was used for the separation, detection and quantification of different components present in the deodorizer distillate in a very short analysis time of 18 min. A simple saponification procedure without derivatization was used for their analysis followed by GC–MS analysis. Phytosterols concentration (21.27–25.53%) was the most abundant in canola and palm distillate samples whereas, squalene and tocopherol were present in concentration ranges of 2.89–13.21% and 1.29–5.81%, respectively. The present study revealed that the unsaponifiable fraction of deodorizer distillate could be used in cosmetic preparations due to its appreciable amount of bioactive constituents. 相似文献
18.
Yuguang Li Jianmin Xing Wangliang Li Xiaochao Xiong Xin Li Huizhou Liu 《Korean Journal of Chemical Engineering》2007,24(5):781-786
High production of Rhodoccus erythropolis LSSE8-1 and its application for the treatment of diesel oils was investigated. Culture conditions were optimized by Taguchi
orthogonal array experimental design methodology. High cell density cultivation of biocatalyst with pH control and fed-batch
feeding strategies was further validated in a fermentor with the optimal factors. Cell concentration of 23.9 g dry cells/L
was obtained after 96 h cultivation. The resting cells and direct fermentation suspension were applied for deep desulfurization
of hydrodesulfurized diesel oils. It was observed that the sulfur content of the diesel decreased from 248 to 51 μg/g by two
consecutive biodesulfurizations. It implied that the biodesulfurization process can be simplified by directly mixing cell
cultivation suspension with diesel oil. The biocatalyst developed with the Taguchi method has the potential to be applied
to produce ultra-low-sulfur petroleum oils. 相似文献
19.
Teresa P. Icenhour Frances M. Van Dolah 《Journal of the American Oil Chemists' Society》1991,68(9):659-661
A rapid, quantitative gas Chromatographic method is described for quantitating the phenolic antioxidant,tert- butyl hydroquinone (TBHQ), in fish oil ethyl esters. The procedure entails silyl derivatization of TBHQ in an acetonitrile
solution of ethyl esters followed by capillary gas chromatography (GC) analysis with an internal standard method of quantitation.
Average recoveries of spiked samples were 98% at the legal limit of .02% (200 μg/g). The method can accurately determine as
little as 20 μ/g of TBHQ in ethyl esters of fish oil. The technique has been applied to ethyl esters of vegetable oils with
equal success. 相似文献
20.
G. R. List T. L. Mounts F. Orthoefer W. E. Neff 《Journal of the American Oil Chemists' Society》1996,73(6):729-732
Genetically modified soybeans were processed into finished, refined, bleached, and deodorized oils. Fatty acid composition
was determined by gas-liquid chromatography. Glyceride structure was characterized according to degree of unsaturation by
high-performance liquid chromatography, lipase hydrolysis, and gas-liquid chromatography. Compared to common varieties with
15% saturated acids, genetically modified soybeans yielded oils containing 24–40% saturated acids. Several varieties were
examined, including the Pioneer A-90, Hartz HS-1, and Iowa State A-6 lines. Pioneer A-90 contained 17% stearic acid, had a
solid fat index (SFI) of 6.0 at 10°C (50°F) and zero from 21.1 to 40°C (70 to 104°F), and therefore lacked sufficient solids
for tub-type margarine. To improve its plastic range, the Pioneer oil was blended with palm oil, randomized palm oil, or interesterified
palm/soy trisaturate basestock. After blending with 10–40% of these components, the high-stearic acid oil had an SFI profile
suitable for soft tube margarine. The A-6 varieties, 32–38% saturates, showed SFI profiles with sufficient solids at 10°C
(50°F) and 21.1°C (70°F) to qualify as a stick-type margarine oil, but lacked sufficient solids at 33.3°C (92°F); however,
after small amounts (2–3%) of cottonseed or soybean hardstocks were added, the A-6 oils qualified as stick margarine oil.
The HS-1 variety, when blended with small amounts (2–3%) of hardstock, possessed sufficient solids at 10°–33.3°C (50–92°F)
to prepare soft tub margarine oil.
Presented at the AOCS Annual Meeting & Expo, San Antonio, Texas, May 8–12, 1995. 相似文献