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1.
Paavo Kalo 《Lipid Technology》2013,25(10):230-234
Isobaric triacylglycerols which differ in the sn‐1(3) and sn‐2 positions of acyl chains are regioisomers. The objective of this review is to describe the resolution of regioisomers by silver‐ion chromatography, RP–HPLC, and by GLC. Furthermore, the aim of this review is to discuss the determination of regioisomers solely by mass spectrometry and by chromatography‐mass spectrometry (GLC and electron ionization MS, silver‐ion chromatography and APCI–MS or ESI–MS, RP–HPLC and APCI–MS, and NP–HPLC and ESI–MS). 相似文献
2.
Determination of the conjugated linoleic acid-containing triacylglycerols in New Zealand bovine milk fat 总被引:1,自引:0,他引:1
Reversed-phase high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection at 233 nm was used to separate,
quantify, and identify the triacylglycerols (TAG) of milk fat that contain conjugated linoleic acid (CLA). The absorbance
at 233 nm was substantially due to CLA-TAG (chromatography of some representative TAG devoid of CLA, such as tripalmitin and
triolein, showed poor responses at 233 nm, 1/800th that of CLA-TAG). A CLA molar extinction coefficient at 233 nm of 23 360
L mol−1 cm−1 and an HPLC UV response factor were obtained from a commercially available cis-9, trans-11-CLA standard. This molar extinction coefficient was only 86% reported literature values. Summation of all chromatographic
peaks absorbing at 233 nm using the corrected response factor gave good agreement with independent determinations of total
CLA by gas chromatography and UV spectrophotometry. This agreement allowed quantification of individual CLA-TAG peaks in the
HPLC separation of a typical New Zealand bovine milk fat. Three CLA-containing TAG, CLA-dipalmitin, CLA-oleoyl-palmitin and
CLA-diolein, were prepared by interesterification of tripalmitin with the respective fatty acid methyl esters and used to
assign individual peaks in the reversed-phase chromatography of total milk fat, of which CLA-oleoyl-palmitin was coincident
with the largest UV peak. Band fractions from argentation thin-layer chromatography of total milk fat were similarly employed
to identify five predominant CLA-TAG groups in total milk fat: CLA-disaturates, CLA-oleoyl-saturates, CLA-vaccenyl-saturates,
CLA-vaccenyl-olein, and CLA-diolein. 相似文献
3.
Regiospecific analysis of triacylglycerols using allyl magnesium bromide 总被引:22,自引:0,他引:22
A method for the regiospecific analysis of triacylglycerols (TAG), using the Grignard reagent allyl magnesium bromide (AMB)
to partially deacylate TAG, is described. 1,3-Distearoyl-2-oleoyl-glycerol (SOS) and 1,3-didecanoyl-2-palmitoyl-glycerol (CPC)
were reacted with AMB. From the resulting mixture, the four different classes of partial acylglycerols and TAG were isolated,
and the mole ratios between stearic acid and oleic acid, or decanoic acid and palmitic acid, respectively, were determined
in each fraction. Different approaches of calculating the composition of the fatty acids in positionssn-1(3) andsn-2 of the original TAG were compared. For thesn-2 position, the best estimate was the direct determination of the fatty acid composition of 2-monoacylglycerol (MAG). Mole
percentages of stearic acid and decanoic acid in thesn-1(sn-3) positions of SOS and CPC, respectively, were most accurately estimated from the fatty acid compositions of TAG and 2-MAG
according to the formula: 1.5×TAG−0.5×2-MAG. Using AMB and the present method of calculation, the results obtained were more
accurate and showed smaller standard derivations than those obtained using other common deacylating agents, such as ethyl
magnesium bromide or pancreatic lipase. 相似文献
4.
The kinetics of isothermal crystallization of binary mixtures of cocoa butter with milk fat and milk fat fractions were evaluated
by applying the Avrami equation. Application of the Avrami equation to isothermal crystallization of the fats and the binary
fat blends revealed different nucleation and growth mechanisms for the fats, based on the Avrami exponent. The suggested mechanism
for cocoa butter crystallization was heterogeneous nucleation and spherulitic growth from sporadic nuclei. For milk fat, the
mechanism was instantaneous heterogeneous nucleation followed by spherulitic growth. For milk fat fractions, the mechanism
was high nucleation rate at the beginning of crystallization, which decreased with time, and plate-like growth. Addition of
milk fat fractions did not cause a significant change in the suggested nucleation and growth mechanism of cocoa butter. 相似文献
5.
Daniela Gastaldi Claudio Medana Valeria Giancotti Riccardo Aigotti Federica Dal Bello Claudio Baiocchi 《European Journal of Lipid Science and Technology》2011,113(2):197-207
Triacylglycerols (TAG) from milk‐fat from different sources (cow, goat and human milks) were characterised using non‐aqueous reversed phase high‐performance liquid chromatography–atmospheric‐pressure chemical ionisation, coupled to MS/MS (RP HPLC‐APCI MS/MS). The fatty‐acid content of all samples was also established by methyl transesterification and GC‐MS analysis. Optimisation of the HPLC gradient, combined with APCI tandem MS, enables TAGs complex mixtures to be analysed without prior separation. More than 160 different glycerides were identified; between 50 and 70 compounds were identified in the chromatograms of each sample. This method also enabled the principal TAG regioisomers to be recognized. The study focused on the investigation of the structure of TAGs containing very‐long‐chain PUFA, namely all cis‐ 4,7,10,13,16,19‐ DHA (DHA, C22:6, n‐3) and all cis‐5,8,11,14,17‐eicosapentaenoic acid (EPA, C20:5, n‐3), both in human and in n‐3‐enriched cow's milks. Ten TAGs containing DHA were identified in human milk and only one in milk from cows fed an n‐3 enriched diet. 相似文献
6.
Argentation thin-layer chromatography was investigated as a method of obtaining detailed compositional information about milk
fat. A modified argentation thin-layer chromatography procedure, developed to optimize the separation of the complex mixture
of total milk fat triacylglycerols, provided nine different groups of triacylglycerols, based on both the degree of unsaturation
and the total length of fatty acid groups. Fatty acid methyl ester (FAME) analysis was performed to determine the composition
of each band. Separation on the basis of chainlength was most pronounced among the fully saturated triacylglycerol groups,
as evidenced by the high level of C4:0 and C6:0 in bands 7 and 8, respectively. For the cis-monoenoic triacylglycerols, the separation of C4:0 and C6:0 was less distinct. The cis,cis dienes and other dienoic, trienoic, or tetraenoic species were principally observed in two bands of retention factor <0.08
on the chromatography plate. Minimal cross-contamination of bands was observed, with the exception of the lowest of the trisaturate
bands, band 7, in which trans-monoenes were found to be present. Three samples from different points of the New Zealand dairy season were separated by
argentation thin-layer chromatography, and their FAME distributions were measured. In addition to differences in the masses
of band extracts from these samples, levels of C10:0 and C12:0 in all bands, and levels of monounsaturates in the dienoic and trienoic bands, were found to differ. These changes were generally
consistent with a pattern of decreasing fat hardness over the November to March period of a typical dairy season. 相似文献
7.
G. A. van Aken E. ten Grotenhuis A. J. van Langevelde H. Schenk 《Journal of the American Oil Chemists' Society》1999,76(11):1323-1331
Milk fat was fractionated by solvent (acetone) fractionation and dry fractionation. Based on their fatty acid and acyl-carbon
profiles, the fractions could be divided into three main groups: high-melting triglycerides (HMT), middle-melting triglycerides
(MMT), and low-melting triglycerides (LMT). HMT fractions were enriched in long-chain fatty acids, and reduced in short-chain
fatty acids and unsaturated fatty acids. The MMT fractions were enriched in long-chain fatty acids, and reduced in unsaturated
fatty acids. The LMT fractions were reduced in long-chain fatty acids, and enriched in short-chain fatty acids and unsaturated
fatty acids. Crystallization of these fractions was studied by differential scanning calorimetry and X-ray diffraction techniques.
In this study, the stable crystal form appeared to be the β′-form for all fractions. At sufficiently low temperature (different
for each fraction), the β′-form is preceded by crystallization in the metastable α-form. An important difference between the
fractions is the rate of crystallization in the β′-form, which proceeds at a much lower rate for the lower-melting fat fractions
than for the higher-melting fat fractions. This may be due to the much lower affinity for crystallization of the lower-melting
fractions, due to the less favorable molecular geometry for packing in the β′-crystal lattice. 相似文献
8.
The triglycerides of bovine milk fat globules were isolated and separated into short, medium and long chain lengths by thin-layer
chromatography. The molecular weight distribution and the fatty acid composition of the component triglycerides was then separately
determined by gas chromatography following argentation-thin-layer and preparative gas chromatography. Some 38 triglyceride
types (28% of total), of which there could be up to 6 isomers, were specifically identified and quantitatively estimated.
The quantitative estimates for the rest of the milk fat triglycerides were limited to much more complex glyceride groups.
The results confirm the earlier claim that butyric and caproic acids occur in milk fat almost exclusively in combination with
medium and long chain fatty acids.
Presented in part at the AOCS Meeting, Philadelphia, October, 1966. 相似文献
9.
Effect of milk fat fractions on fat bloom in dark chocolate 总被引:4,自引:0,他引:4
Anhydrous milk fat was dissolved in acetone (1∶4 wt/vol) and progressively fractionated at 5°C increments from 25 to 0°C.
Six solid fractions and one 0°C liquid fraction were obtained. Melting point, melting profile, solid fat content (SFC), fatty
acid and triglyceride profiles were measured for each milk fat fraction (MFF). In general, there was a trend of decreased
melting point, melting profile, SFC, long-chain saturated fatty acids and large acyl carbonnumbered triglycerides with decreasing
fractionation temperature. The MFFs were then added to dark chocolate at 2% (w/w) addition level. In addition, two control
chocolates were made, one with 2% (w/w) full milk fat and the other with 2% (w/w) additional cocoa butter. The chocolate samples
were evaluated for degree of temper, hardness and fat bloom. Fat bloom was induced with continuous temperature cycling between
26.7 and 15.7°C at 6-h intervals and monitored with a colorimeter. Chocolate hardness results showed softer chocolates with
the 10°C solid fraction and low-melting fractions, and harder chocolates with high-melting fractions. Accelerated bloom tests
indicated that the 10°C solid MFF and higher-melting fractions (25 to 15°C solid fractions) inhibited bloom, while the lowermelting
MFFs (5 and 0°C solid fractions and 0°C liquid fraction) induced bloom compared to the control chocolates. 相似文献
10.
Comparative study of the molecular species of chloropropanediol diesters and triacylglycerols in milk fat 总被引:1,自引:0,他引:1
In an effort to establish the origin of the fatty acid esters of 3-chloropropanediol, which recently have been isolated in
small amounts from goat milk, we compared the molecular species composition of the chlorohydrin diesters and of goat milk
triacylglycerols. The chloropropanediol diesters were found to be composed of molecular species containing C10−C18 fatty acids and corresponded closely in carbon number to those calculated for the long chain sn-1,2-diacyl-glycerol moieties
of goat milk triacylglycerols. The molecular species of goat milk total triacylglycerols contained C4−C18 fatty acids. It is suggested that triacylglycerols and chloropropanediol diesters are derived from the same pool of long
chain fatty acids. A molecular distillate of bovine milk fat did not contain chloropropanediol diesters, while the available
samples of human milk fat were shown to contain alkyldiacylglycerols as the major components of a neutral lipid fraction corresponding
in polarity to the chloropropanediol diesters. 相似文献
11.
A reversed-phase high-performance liquid chromatography (HPLC) method was developed for the purpose of analyzing milk fat triacylglycerols by evaporative light scattering detection. With a binary solvent system, comprising dichloromethane and acetonitrile, the method allowed a separation of 61 distinct peaks, on the basis of chainlength and number of double bonds. Triacylglycerols of differing partition numbers were clearly resolved, and the resolution between peaks of the same partition number was high. An argentation thin-layer chromatography method, separating triacylglycerols on the basis of chainlength and degree of unsaturation, provided nine band extracts that were analyzed by HPLC. By using existing fatty acid methyl ester data of these bands, an identity for each HPLC peak has been proposed. 相似文献
12.
Dibutyroyl derivatives of monoacylglycerols (DBMAG) from conifer seed oil triacylglycerols (TAG) were prepared by partial
deacylation of TAG with ethylmagnesium bromide followed by diesterification with n-butyryl chloride. The resulting mixtures were analyzed by gas-liquid chromatography (GCL) with 65% phenylmethyl silicon open
tubular fused-silica capillary column operated under optimal conditions and separated according to both their fatty acid structures
and their regiospecific distribution. Seed oils of 18 species from 5 conifer families (Pinaceae, Taxaceae, Cupressaceae, Cephalotaxaceae,
and Podocarpaceae) were analyzed. The chromatograms showed a satisfactory resolution of DBMAG containing palmitic (16∶0) stearic
(18∶0), taxoleic (cis-5, cis-9 18∶2), oleic (cis-9 18∶1), cis-vaccenic (cis-11 18∶1), pinolenic (cis-5, cis-9, cis-12 18∶3), linoleic (cis-9, cis-12 18∶2), α-linolenic (cis-9 cis-12, cis-15 18∶3), and an almost baseline resolution of DBMAG containing gondoic (cis-11 20∶1), cis-5, cis-11 20∶2, sciadonic (cis-5, cis-11, cis-14 20∶3), dihomolinoleic (cis-11 cis-14 20∶2), juniperonic (cis-5, cis-11, cis-14, cis-17 20∶4), and dihomo-α-linolenic (cis-11, cis-14, cis-17 20∶3) acids. We have observed that results for Pinus pinaster and P. koraiensis seed oils obtained with this new simple method compared favorably with literature data established with other usual regiospecific
analytical techniques. Δ5-Olefinic acids are esterified mainly at the external positions of the glycerol backbone in all cases,
in agreement with data obtained by other methodologies allowing validation of the GLC regiospecific method. To date, 45 gymnosperm
species (mostly Coniferophytes) from 21 genera belonging to 9 families have been analyzed, all of them showing a definite
enrichment of Δ5-olefinic acids in the external positions of TAG. These fatty acids (FA), with one exception only, represent
between-2 and 8% of FA esterified to the internal positions. For some species, i.e., P. koraiensis and P. pinaster, this asymmetrical distribution was established by at least three analytical procedures and confirmed by stereospecific analysis
of their seed TAG. 相似文献
13.
The utility of reverse-phase high-performance liquid chromatography (HPLC), desorption chemical-ionization mass spectrometry
(DCI-MS) and tandem mass spectrometry (MS/MS) for the characterization of triacylglycerols in complex mixtures has been further
explored. Triacylglycerols of anhydrous bovine milk fat were separated by using two reversephase C18 HPLC columns, and eluents were monitored with an evaporative light-scattering detector. Fifty-eight fractions were resolved
and analyzed by positive ion isobutane DCI-MS. The formation of protonated molecules and of major fragments corresponding
to the random loss of any one of the constituent fatty acids readily identified acyl carbon numbers and the number of double
bonds within each fatty acid. MS/MS was only required when the original mass spectra indicated the presence of more than one
triacylglycerol or of impurities in a fraction. Protonated molecules produced by DCI were fragmented using high energy collisional
activation, and the resulting ions were detected by MS/MS. Odd-chain triacylglycerols were also readily distinguished using
this methodology. The positive ion DCI and MS/MS techniques described here demonstrate the usefulness of this approach for
the characterization of triacylglycerols in complex mixtures. 相似文献
14.
Nanneke J. de Fouw Gerard A. A. Kivits Paul T. Quinlan Wim G. L. van Nielen 《Lipids》1994,29(11):765-770
The effect of the positional distribution of palmitic acid (16∶0) in triacylglycerols (TAG) on 16∶0 apparent absorption in
adult rats was investigated. The rats were fed two diets which contained 30 energy % as fat with identical total fatty acid
compositions, both containing 30% 16∶0. The Betapol diet contained TAG with 73% of total 16∶0 in thesn-2 position, the control diet contained TAG with 6% of total 16∶0 in thesn-2 position. After six weeks on these diets, the rats were killed two or six hours after the last meal, and the small intestine
was removed, cut into 10-cm segments, and the fatty acid composition of the segment's contents was determined. At both time
points the amount of 16∶0 in the intestinal segments starting at 40 cm from the stomach was much lower in the animals fed
Betapol than in the animals fed the control diet. Overall absorption of 16∶0 and stearic acid was significantly greater in
the Betapol group. Absorption of oleic and linoleic acid from the small intestine was similar in both groups, although the
overall absorption was significantly greater in the animals fed Betapol. Total fat absorption was significantly higher in
the Betapol-fed rats than in the control-fed rats. No effect on calcium and nitrogen absorption, on plasma total cholesterol
and TAG levels, and on bodyweights (growth) was seen. The data demonstrate that the positional distribution of the fatty acids
in the TAG molecule affects the site of absorption in the small intestine and particularly the net absorption of saturated
fatty acids. 相似文献
15.
J. L. Moore T. Richardson C. H. Amundson 《Journal of the American Oil Chemists' Society》1965,42(9):796-799
Five fractions of anhydrous milk fat were obtained by fractional crystallization in the absence of solvent. The fractions
were characterized, physically and chemically, before and after interesterification.
Cholesterol tended to fractionate into the lowest-melting fraction.
Slipping points of 38.5C, 32C, 28C, 22.5C, and 17C, respectively, were reflected in widely varying micropenetration curves,
while differences in fatty acid composition were relatively small. The three higher-melting fractions, with very similar fatty
acid compositions, had very similar physical properties after interesterification. Slipping points of 38C, 37C, 37C, 33C,
and 32C, respectively, indicated that interesterification generally hardened the fractions. Interesterification altered the
physical properties of lower-melting fractions more than the properties of higher-melting fractions.
Interesterification caused some triglyceride degradation and some butyrate loss, but these factors could not fully explain
the unequal physical property changes induced in the different fractions.
Fractionation possibly tends to separate symmetrical triglycerides from their lower-melting, unsymmetrical isomers, yielding
fractions with apparent differences in the degree of randomness of their triglyceride structure.
Positioning of fatty acids within the triglyceride molecule seems to be a principal determinant of the physical properties
of milk fat fractions.
Published with approval of the Director of the Wisconsin Agricultural Experiment Station. 相似文献
16.
The effect of increasing the linoleic acid (18∶2) content of milk fat on the composition and structure of the triglycerides
(TG) was investigated. Protected sunflower seed supplement was added to the diet of a cow grazing on pasture, and the structure
and composition of the milk fat compared with the milk fat from its monozygous twin which had been fed a control diet. The
relative proportions of TG fractions of high, medium, and low molecular weight in the milk fat with elevated levels of 18∶2
(15.5% 18∶2) were 43.0, 19.5, and 37.5 moles %, respectively, compared with 36.1, 19.7, and 44.2 moles %, respectively, in
the milk fat from the cow fed the control diet. Separation of these three TG fractions of each milk fat into TG classes with
different levels of unsaturation showed that the milk fat with elevated levels of 18∶2 contained higher proportions of diene,
triene, and tetraene TG and correspondingly lower proportions of saturated and, to a lesser extent, monoene TG. The saturated
and monoene TG from the two milk fats had similar fatty acid compositions. However, the diene TG of the 18∶2-rich milk fat
included high proportions of the combination of 18∶2 with two saturated fatty acids (FA) which are minor constituents of normal
milk fats. Likewise, the triene TG reflected the presence of 18∶2 in combination with 18∶1 and a saturated FA. 相似文献
17.
Identification of milk fat triacylglycerols was accomplished by capillary supercritical fluid chromatography (SFC) combined
with atmospheric pressure chemical ionization mass spectrometry [(APCI)MS]. Supercritical carbon dioxide was the carrier fluid
in SFC. Ionization was achieved by introducing vapor of ammonia in methanol into the ionization chamber, which resulted in
the formation of abundant [M+18]+ and [M-RCOO]+ ions of triacylglycerols. These ions defined both the molecular weight and the fatty acid constituents of a triacylglycerol,
respectively. SFC on a nonpolar stationary phase provided an efficient separation of triacylglycerols according to the combined
number of carbon atoms in the acyl chains of a molecule. In addition to the identification of the major chromatographic peaks
representing molecules with 26–54 acyl carbons, minor peaks representing triacylglycerols with an odd number of acyl carbons
were separated and identified. Furthermore, compositional information on partially separated isobaric triacylglycerols, which
differed substantially in the chain length of the fatty acyl residues, was achieved within some of the peaks. A new finding
of the present study was the formation of abundant [M+18]+ ions of saturated triacylglycerols in addition to diagnostic fragment ions, being of primary importance in structure elucidation.
This extends the applicability of capillary SFC-(APCI)MS in the analysis of both saturated and unsaturated triacylglycerols. 相似文献
18.
B. Petersson O. Podlaha B. Töregård 《Journal of the American Oil Chemists' Society》1981,58(11):1005-1009
A high performance liquid Chromatographie method was developed and tested on palm oil, low-erucic-acid rapeseed oil and cocoa
butter. A 100-cm long column was used, packed with Nucleosil 5 C18 and using acetonitrile/acetone, 60:40 (v/v) as mobile phase.
Using this system, the oils could be separated directly into fractions specified by having the same carbon number and number
of double bonds. Earlier, the same fractionation could be obtained only by a 2-step Chromatographie separation. The fractions
have been found to be very pure and to have simple triglyceride composition with only one totally dominating triglyceride
type in almost all cases. 相似文献
19.
This study uses normal-phase HPLC with on-line positive ion electrospray mass spectrometry (ESI-MS) to obtain quantitative
compositional data on both synthetic and butterfat short-chain TAG. The product ion tandem MS of standards averaged 11.1 times
lower in abundance of the ion formed by cleavage of FA from the sn-2-position for the pairs of regioisomers in the TAG classes: L/L/S-L/S/L and L/S/S-S/L/S, where L denotes long and S short
acyl chain (C2−C6). The molar correction factors, determined for 42 regioisomeric pairs of short-chain TAG of 20 randomized mixture of standards,
differed by 1.4–80% as the ratios varied between 0.217 and 5.847. Butterfat TAG were resolved into four fractions on short
flash chromatography grade silica gel columns. Pairs of regioisomers in the TAG classes L/S/S-S/L/S with predominance of L/S/S
isomers and the sole regioisomers in the TAG classes L/L(M)/S were identified by tandem MS, where M denotes either 8∶0 or
10∶0 acyl chain. The total proportion of L/L(M)/S isomers was estimated at 34.7 and that of L/S/S-S/L/S at 1.0 mol%, including
a small proportion of S/S/S. In contrast to previous work, the present data indicate the presence of a small proportion of
butyric and caproic acids in the sn-1-position. The overall distribution of the FA in the short-chain TAG of butterfat, calculated from direct MS measurements,
was consistent with the results of indirect determinations based on stereospecific analyses of total butterfat. 相似文献
20.
A refractometric method for the estimation of iodine number of milk fat has been suggested. About 0.2 ml of milk fat was iodinated
with ca. 10 ml Wijs iodine reagent for 3 min using mercuric acetate as catalyst. The iodinated fat showed a higher refractive
index than the original fat. The changes in refractive indices showed a very high correlation with the iodine values of the
fats (T=0.9993). The average of the ratios of change in refractive index to iodine number was 50.7×10−5, from which the iodine number of milk fat can be calculated. The method can also be applied to vegetable fats. The ratios
of change in refractive index to iodine number for the oils of peanut, rapeseed, soybean, niger, sesame, and sunflower were
similar, and the average was 45.2×10−5. The ratio for linseed oil was 38.4×10−5, and for coconut fat it was similar to that of milk fat. 相似文献