共查询到20条相似文献,搜索用时 15 毫秒
1.
Marcel S. F. Lie Ken Jie C. C. Lam Mohammed Khysar Pasha Kamen L. Stefenov I. Marekov 《Journal of the American Oil Chemists' Society》1996,73(8):1011-1017
The triacylglycerol fraction of three samples of margarine, namely “Flora” (Holland), “Kaliakra” (Bulgaria), and “Corona”
(Holland), were studied by13C nuclear magnetic resonance spectroscopy. By examining the various carbon chemical shifts of the saturated and unsaturated
carbon nuclei, “Flora” margarine was shown to contain a mixture of hydrogenated and unhydrogenated vegetable oils. This technique
allowed all major acyl groups (saturated, oleate, linoleate, and linolenate) and minor acyl components [different positional
isomers of long-chain (E)- and (Z)-monoenoic moieties, arising as by-products during catalytic hydrogenation] to be identified. The amount of each fatty acid
present in the margarine was also estimated from the relative intensities of the corresponding signals. “Kaliakra” margarine
consisted of a blend of unhydrogenated natural fats and oils that contained saturated fatty acids, oleate, and linoleate.
There were no signs in the spectrum of “Kaliakra” of any (E)-isomers, nor signals associated with positional unsaturated acyl groups (other than oleate and linoleate). The sample of
“Corona” margarine consisted of a mixture of hydrogenated and unhydrogenated vegetable oils and butter (1.3%). The presence
of butter in this sample was identified by the characteristic carbon shifts of the C-1 to C-4 carbon atoms of butyrate. The
distribution of the fatty acids on the glycerol “backbone” also was estimated by this technique. 相似文献
2.
Soon Ng 《Journal of the American Oil Chemists' Society》2000,77(7):749-755
The chemical shifts, spin-lattice relaxation times (T 1), and one-bond C−H coupling constants of the glycerol carbons of mono-, di-, and triacylglycerols in CDCI3 solution are presented and discussed. The glycerol carbons have low T 1 values (<1.0 s) and full nuclear Overhauser effect and also exhibit broader linewidths than the aliphatic carbons, suggesting that the glycerol carbons are at or near the T 1 minimum for the dipole-dipole relaxation mechanism. Therefore, for quantitative measurement of the composition of partial acylglycerols (relative to the triacylglycerols) in palm oil, the nuclear magnetic resonance (NMR) spectrum of the β-carbons, which lie exclusively in the region δ68.3–72.1 ppm, should preferably be acquired at medium or low magnetic fields and at an elevated temperature in order to ensure that the condition for extremely narrow spectral lines is satisfied. The chemical shifts and spinlattice relaxation times of the aliphatic C-2 and C-3 carbons and of the carbonyl carbons (C-1) of acyl groups present in palm oil are also presented and discussed. The presence of free fatty acid in the palm oil is easily detected and quantified in the spectrum of the aliphatic carbons. The presence of partial acylglycerols in palm oil can also be detected and/or quantified in the NMR spectra of the C-2 and the carbonyl carbons. The quantitative analysis of the glycerol carbons of a known mixture of acylglycerols obtained by using this method is presented. 相似文献
3.
J. F. Mallet E. M. Gaydou A. Archavlis 《Journal of the American Oil Chemists' Society》1990,67(10):607-610
Synthetic triolein and tripetroselinin mixtures were examined by13C NMR spectroscopy, showing marked chemical shift differences of the olefinic carbon atoms. Peak height ratios were compared
to weight values for quantitative determination of oleic and petroselinic acids in seed oils, since these two fatty acids
are quantitated together by GC analysis. Values observed for NMR peak height ratios were fairly close and agreed well with
weight ratios. From overall compositions of eleic and petroselinic acids obtained by GC and relative compositions given by13C NMR, petroselinic acid has been determined in tenUmbelliflorae seed oils. 相似文献
4.
The application of13C nuclear magnetic resonance to determine the positional distribution of fatty acids on the glycerol backbone has been investigated.
A systematic approach and synthetic triacylglycerols were used to measure the effect on the carbonyl chemical shifts of triacylglycerols
by the positional distribution on the glycerol backbone and the number and position of the double bonds within the fatty acids.
The correlation of13C carbonyl chemical shift to the molecular structure of triacylglycerol was delineated. The assignments for the chemical shifts
of the carbonyl nuclei of monoacyltriacylglycerol standards were compiled. The resonance from the carbonyl carbons at the
1,3 positions is resolved from that at the 2 position. The13C carbonyl chemical shift was more dependent on the position of the double bonds than the degree of unsaturation of the fatty
acids. In particular, little effect was observed in the chemical shifts for fatty acids containing more than two double bonds.
However, the chemical shifts were influenced significantly by the position of the first double bond. The difference in the
chemical shift of the unsaturated species from that of the saturated species was plotted against the position of the first
double bond. A natural logarithmic relationship was found between carbon numbers 5 and 11. Inflection points were found outside
of this region at carbon numbers 4 and 13. In addition, the resonances from the saturated species, independent of their chainlength,
were degenerate in oil systems, even though small differences were observed in the standards. The applicability of this method
was demonstrated in the determination of the composition and positional distribution of the fatty acids in borage and evening
primrose oils. 相似文献
5.
Pierre Blaise Marie Farines Jacques Soulier 《Journal of the American Oil Chemists' Society》1997,74(6):727-730
Gorlic, chaulmoogric and hydnocarpic fatty acids, specific to the seed oil of the genus Hydnocarpus sp. (Flacourtiaceae), are determined only with difficulty by gas chromatography. These fatty acids were isolated in their
methyl ester form by a combination of different chromatographic techniques (thin-layer chromatography/Ag+ and high-pressure liquid chromatography). The proton and carbon nuclear magnetic resonance analysis of these fatty acid methyl
esters showed some characteristic signals of the cyclopentenyl ring. The presence of these signals in the proton and/or carbon
nuclear magnetic resonance spectrum of an oil thus will allow us to confirm the presence of these cyclopentenyl fatty acids
in lipids. 相似文献
6.
Giovanna Vlahov Adrian D. Shaw Douglas B. Kell 《Journal of the American Oil Chemists' Society》1999,76(10):1223-1231
Distortionless enhancement by polarization transfer (DEPT) pulse sequence was used to set up a quantitative high-resolution
13C nuclear magnetic resonance (NMR) method to discriminate olive oils by cultivars and geographical origin. DEPT pulse sequence
enhances the intensity of NMR signals from nuclei of low magnetogyric ratio. The nuclear spin polarization is transferred
from spins with large Boltzmann population differences (usually protons) to nuclear species characterized by low Boltzmann
factors, e.g., 13C. The signal enhancement of 13C spectra ensures the accuracy of resonance integration, which is a major task when the resonance intensities of different
spectra must be compared. The resonances of triglyceride acyl chains C
n:0, C18:1, C18:2, and C18:3, were also assigned. Multivariate analysis was carried out on the 35 carbon signals obtained. By using variable reduction
techniques, coupled with standard statistical methods—partial least squares and principal components analysis—it was largely
possible to separate the samples according to their variety and region of origin. With one problem variety removed, 100% prediction
of the three remaining varieties was achieved. Similarly, by using the three regions with greatest representation in the data,
all but one of a test set of 34 samples were correctly predicted. Thus, the composition of olive oils from different cultivars
and of different geographical origin were compared and successfully studied by multivariate analysis. These considerations
in conjunction with the structural elucidations of triglyceride molecules demonstrated that 13C NMR is among the most powerful techniques yet described for analysis of olive oils. 相似文献
7.
Yuko Miyake Kazuhisa Yokomizo Narihide Matsuzaki 《Journal of the American Oil Chemists' Society》1998,75(12):1091-1094
High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of
edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the
1H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic
acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these
acids by the 13C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC)
method. Results from 13C NMR were in better agreement with those from GC than were the results obtained by the 1H NMR method. 相似文献
8.
Yuko Miyake Kazuhisa Yokomizo Narihide Matsuzaki 《Journal of the American Oil Chemists' Society》1998,75(9):1091-1094
High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the 1H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these acids by the 13C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC) method. Results from 13C NMR were in better agreement with those from GC than were the results obtained by the 1H NMR method. 相似文献
9.
Frank D. Gunstone 《Journal of the American Oil Chemists' Society》1993,70(10):965-970
The high-resolution13C nuclear magnetic resonance spectra of twelve hydrogenated fats have been examined. Each spectrum contains 50–100 signals
and reveals much about the nature of the acyl chains of both double-bond position and configuration. The signals for the ω1,
ω2 and ω3 carbon atoms give information on thecis andtrans isomers of the Δ15, Δ14, Δ13 and Δ12 18:1 esters, respectively. Allylic signals distinguish betweencis andtrans esters, and the proportion of totalcis to totaltrans isomers can be obtained from these. Olefinic signals are the most informative, and most of these have been assigned. This
leads to a semi-quantitative estimate of the various 18:1 isomers present. Assignments are based mainly on information already
in the literature, but some were confirmed after urea fractionation of the acids from a hydrogenated oil in whichcis andtrans monoene acids were separately concentrated. 相似文献
10.
Kurt F. Wollenberg 《Journal of the American Oil Chemists' Society》1990,67(8):487-494
The acyl distribution and acyl positional distribution (1,3-acyl and 2-acyl) of triacylglycerols derived from edible vegetable oils has been examined by13C nuclear magnetic resonance (NMR) spectroscopy. The acyl profile of three natural oils (corn, peanut, canola) and one specialty oil (high oleic sunflower oil, Trisun® 80) has been defined from the high resolution (medium field 75.4 MHz) spectrum of the carbonyl and olefinic regions. The quantitative integrity of the NMR derived acyl profile is substantiated by gas chromatographic (GC) analysis. The positional distribution data of the three natural oils indicates that polyunsaturates are replaced in the 1,3-glycerol position exclusively by saturates, while the oley distribution remains, for the most part, randomly distributed. The same is not true for Trisun® 80, which shows a more random distribution of the linoleyl groups as well. 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.
Giovanna Vlahov 《Journal of the American Oil Chemists' Society》1996,73(9):1201-1203
A quantitative method was established to determine the presence and composition of mono-, di-, and triglycerides of olive
oils of superior gradevia
13C NMR. The total diglyceride content and the ratio ofsn-1,2- andsn-1,3-diglycerides in extra virgin oils extracted from different olive cultivars were correlated with maturity. The correlation
can be applied to identify the oils by variety. No monoglycerides were detected in the oils examined. 相似文献
13.
Frank D. Gunstone 《Journal of the American Oil Chemists' Society》1993,70(11):1139-1144
The13C nuclear magnetic resonance spectra ofVernonia galamensis seed oil and of epoxidized palm super olein, soybean oil and linseed oil have been recorded and interpreted. The chemical
shifts of the major signals are assigned and semi-quantitative results are derived. The spectroscopic procedure provides a
useful method of analyzing oils that contain epoxy acids. The epoxide function differs from a double bond in its influence
on the chemical shifts of nearby carbon atoms. 相似文献
14.
Frank D. Gunstone Robert L. Wolff 《Journal of the American Oil Chemists' Society》1996,73(11):1611-1613
Nine seed oils from three different conifer families, already examined by gas chromatography and known to contain diene, triene,
and tetraene C18 and C20Δ5 acids, have been reexamined by high-resolution13C nuclear magnetic resonance spectroscopy. The Δ5 acids are apparent only in the α-chains. This location is independent of
chainlength, double-bond number, and the species considered and is probably a general factor of conifer seed oils. The spectra
confirm the presence of oleic, linoleic, α-linolenic, and of Δ5 acids and give quantitative information about (total) n-6,
n-3, and Δ5 acids that is in accord with that obtained by gas chromatography. 相似文献
15.
Rosario Zamora José L. Navarro Francisco J. Hidalgo 《Journal of the American Oil Chemists' Society》1994,71(4):361-364
Unsaponifiable matter from 19 olive and olive pomace oils were studied by high-resolution13C nuclear magnetic resonance spectroscopy. Their spectra showed characteristic peaks that corresponded to molecular substructures
rather than the individual constituents present in the unsaponifiable matter. The presence of squalene and other hydrocarbons,
sterols and triterpenic alcohols, in addition to other groups of minor compounds, were observed. Based on the analysis of
these spectra, it was possible to distinguish among different grades of olive oils by using stepwise discriminant analysis.
This direct method of analysis is suggested to be used in artificial neural networks to define oil identity and quality. 相似文献
16.
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
17.
R. Maurin K. Fellat-Zarrouck M. Ksir 《Journal of the American Oil Chemists' Society》1992,69(2):141-145
The distribution of fatty acids between the sn-1, sn-2 and sn-3 positions of triacylglycerols fromArgania spinosa seed oil of Morocco has been determined. Saturated fatty acids showed a preference for external positions. The sn-1 position
contained slightly more palmitic acid than the sn-3 position, whereas stearic acid was preferentially esterified at the sn-3
position. Linoleic acid occurred predominantly in the sn-2 position with lesser amount evenly distributed between the sn-1
and the sn-3 positions, as generally found in vegetable oils. Oleic acid was distributed with a slight preference shown for
the internal position, whereas the distribution between the external positions revealed a slight preference for the sn-1 position.
The distribution of the triacylglycerols determined from high-performance liquid chromatography (HPLC) is at variance with
that calculated from the 1-random 2-random 3-random distribution theory. This is particularly true for trioleoyl and trilinoleoylglycerols.
In contrast, the agreement between theory and experiment is good for triacylglycerols containing two oleoyl and one linoleoyl
chains, one oleoyl, one linoleoyl and one palmitoyl chains or one oleoyl, one palmitoyl, and one stearoyl chains. 相似文献
18.
Carbon nuclear magnetic resonance (13C NMR) methods for determining the composition of cis-/trans- and positional isomers in hydrogenated vegetable oils were developed to reduce analytical time. By selecting appropriate olefinic carbon peaks and by measuring individual peak areas subsequent to the identification of isomeric peaks on the NMR spectrum, compositional results of the isomers coincided well with those obtained by conventional gas chromatography (GC). Therefore, it is highly beneficial to choose the 13C NMR method when analysis time is limited. Though the proposed 13C NMR method is promising, further development is needed. For the time being, combination with the traditional GC method is still encouraged for precise compositional analysis of cis-/trans- and positional isomers. 相似文献
19.
A. S. Charvet L. C. Comeau E. M. Gaydou 《Journal of the American Oil Chemists' Society》1991,68(8):604-607
Pure petroselinic acid (cis-6-octadecenoic acid) has been isolated from fennel oil by acid soap crystallization at 4°C in methanol, followed by two urea
segregations at room temperature and crystallization at −30°C in acetone. The purity control of petroselinic acid was effected
by combined gas chromatography, and13C nuclear magnetic resonance. This petroselinic acid preparation was compared to other previous crystallization or enzymatic
methods, showing that this method is both short (four steps) and easy to apply. 相似文献
20.
F. Jahaniaval Y. Kakuda M. F. Marcone 《Journal of the American Oil Chemists' Society》2000,77(8):847-852
This paper reports the fatty acid and triacylglycerol (TAG) compositions of five Amaranthus accessions (RRC1011, R149, A.K343, A.K432, and A. K433) representing two species and a cross between one of these and a third species. Seed oils of these were analyzed by
gas chromatography and reversed-phase high-performance liquid chromatography, and their compositional properties compared
with buck-wheat (Fagopyrum esculentum), corn (Zea mays), rice bran (Oryza sativa), soybean (Glycine max L. Merr.), sesame (Sesamum indicum), quinoa (Chenopodium quinoa), and cottonseed (Gossypium hirsutum) oils. All Amaranthus accessions were relatively high in palmitic (21.4–23.8%) and low in oleic (22.8–31.5%) and linolenic (0.65–0.93%) acids when
compared to most of the grain and seed oils. The fatty acid composition of Amaranthus accessions K343, K433, and K432 (group I) were different from R149 and RRC1011 (group II) in mono and polyunsaturated fatty
acids, but the saturate/unsaturate (S/U) ratios were very similar. All Amaranthus accessions were similar in TAG type, but showed slight differences in percentage. High similarities in UUU, UUS, and USS
composition were observed among Amaranthus K343, K433 and K432, and between R149 and RRC1011. The fatty acid compositions of Amaranthus oil (group I) and cottonseed oil were similar, but their TAG compositions were different. The grain and oilseed oils were
different from each other and from the Amaranthus accessions oils in terms of fatty acid composition, S/U, and TAG ratios. The UUU, UUS, and USS percentages were very diverse
in grain and seed oils. The percentages of squalene in the TAG sample from the Amaranthus accessions were 8.05% in K343, 11.10% in K433, 11.19% in K432, 9.96% in R149, and 9.16% in RRC1011. Squalene was also tentatively
identified in quinoa and ricebran oils at levels of 3.39 and 3.10%, respectively. 相似文献