Lymphatic fatty acids from rats fed human milk and formula containing coconut oil

Human milk and infant formula containing coconut/soy oil were infused into the duodenum of rats to determine the incorporation of capric, lauric, myristic and palmitic acids into lymphatic triacylglycerol (TAG). The proportion of capric and lauric acids in the lymphatic TAG reflected the fatty acid composition of the diet. Based on positional analysis, it appears that more than 50% of the capric and lauric acids could have been absorbed from the intestine assn-2 monoacylglycerols. In the rats fed human milk, 50% of palmitic acid in lymphatic TAG was in thesn-2 position. Because of the nonrandom distribution of palmitic acid in the lymphatic TAG, the nonspecific lipase in human milk, i.e., bile salt-stimulated lipase, did not appear to be a factor in milk lipid digestion.     

Positional distribution of the fatty acids in the triglycerides of mango (Mangifera indica) kernel fat

Triglycerides of mango seed kernel fat contain, depending on the variety, 32.4–44.0% of stearic acid and 43.7–54.5% of oleic acid. Palmitic and linoleic acids represent, respectively, 5.9–9.1% and 3.6–6.7% of the fatty acids. The triglycerides also contain minor amounts of arachidic and linolenic acids. Palmitic, stearic and arachidic acids were almost exclusively distributed among thesn-1-andsn-3-positions. Oleic acid represented 85–89% of the fatty acids at thesn-2-position. Oleic acid at thesn-1- andsn-3-positions showed a preference for thesn-1-position. Linoleic acid was mainly esterified at thesn-2-position. The amounts of saturated fatty acids, i.e., palmitic and stearic acids, and of oleic acid, at thesn-1- and sn-3-positions, were linearly related to their respective contents in the total triglycerides.     

Regiospecific analysis of triacylglycerols using allyl magnesium bromide

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.     

Comparison of the Structures of Triacylglycerols from Native and Transgenic Medium-Chain Fatty Acid-Enriched Rape Seed Oil by Liquid Chromatography–Atmospheric Pressure Chemical Ionization Ion-Trap Mass Spectrometry (LC–APCI-ITMS)

The sn position of fatty acids in seed oil lipids affects physiological function in pharmaceutical and dietary applications. In this study the composition of acyl-chain substituents in the sn positions of glycerol backbones in triacylglycerols (TAG) have been compared. TAG from native and transgenic medium-chain fatty acid-enriched rape seed oil were analyzed by reversed-phase high performance liquid chromatography coupled with online atmospheric-pressure chemical ionization ion-trap mass spectrometry. The transformation of summer rape with thioesterase and 3-ketoacyl-[ACP]-synthase genes of Cuphea lanceolata led to increased expression of 1.5% (w/w) caprylic acid (8:0), 6.7% (w/w) capric acid (10:0), 0.9% (w/w) lauric acid (12:0), and 0.2% (w/w) myristic acid (14:0). In contrast, linoleic (18:2n6) and alpha-linolenic acid (18:3n3) levels decreased compared with the original seed oil. The TAG sn position distribution of fatty acids was also modified. The original oil included eleven unique TAG species whereas the transgenic oil contained sixty. Twenty species were common to both oils. The transgenic oil included trioctadecenoyl-glycerol (18:1/18:1/18:1) and trioctadecatrienoyl-glycerol (18:3/18:3/18:3) whereas the native oil included only the latter. The transgenic TAG were dominated by combinations of caprylic, capric, lauric, myrisitic, palmitic (16:0), stearic (18:0), oleic (18:1n9), linoleic, arachidic (20:0), behenic (22:0), and lignoceric acids (24:0), which accounted for 52% of the total fat. In the original TAG palmitic, stearic, oleic, and linoleic acids accounted for 50% of the total fat. Medium-chain triacylglycerols with capric and lauric acids combined with stearic, oleic, linoleic, alpha-linolenic, arachidic, and gondoic acids (20:1n9) accounted for 25% of the transgenic oil. The medium-chain fatty acids were mainly integrated into the sn-1/3 position combined with the essential linoleic and alpha-linolenic acids at the sn-2 position. Eight species contained caprylic, capric, and lauric acids in the sn-2 position. The appearance of new TAG in the transgenic oil illustrates the extensive effect of genetic modification on fat metabolism by transformed plants and offers interesting possibilities for improved enteral applications.     

Peanut triacylglycerols: Effect of season and production location

Stereospecific analysis of triacylglycerols from 4 peanut varieties grown for up to 3 years at 4 locations showed diversity in percentage fatty acid placement. Distribution of oleic and linoleic acids at each position was significantly correlated to the amount in the total triacylglycerol for varieties grown at one location. However, correlations for thesn-3 position were not significant when data from more than one location were analyzed together. Generally, higher percentages of oleic or linoleic acid in the triacylglycerol resulted in a greater proportion of the particular fatty acid in thesn-2 position. Apparently, fatty acid concentrations as influenced by growing location have a significant influence on peanut triacylglycerol structure.     

Distribution of the major fatty acids of human milk betweensn-2 andsn-1,3 positions of triacylglycerols

Human milk triacylgycerols (TAG) were analyzed by tandem mass spectrometry. The SIMPLEX method and a simple linear model were used to interpret the distribution of fatty acids between thesn-2 andsn-1,3 positions in 24 major molecular weight groups of TAG. The number of regio-isomeric pairs of TAG varied between 3 and 18 in each of these groups. Hexadecanoic (16∶0), tetradecanoic (14∶0) and dodecanoic acids (12∶0) typically occupied thesn-2 position in TAG containing less than 54 acyl carbons, whereas long-chain C18 and C20 acids were predominantly located at the primary positions. The positions of the three fatty acids within a TAG molecule were shown to depend on the fatty acid combination. The maximum of 12∶0 in thesn-2 position appeared at acyl carbon number (ACN) 48, the maxima of 14∶0 were at ACN 44 and ACN 50, and for 16∶0 at ACN 46 and 52.     

Glyceride structure variation in soybean varieties: I. Stereospecific analysis

Stereospecific analysis of soybeans and related species showed that there was little palmitic or stearic acid on thesn-2-position, and thesn-1-position is consistently richer in palmitic, stearic, and linolenic acids than thesn-3-position. Thesn-3-position is enriched in oleic acid and thesn-2-position with linoleic. Plots of the percentage of fatty acids on the glycerol positions vs. the percentage in the whole oil revealed a soybean variety that had a deviant distribution that is probably genetically controlled. Journal Paper No. J-8837 of the Iowa Agriculture and Home Economics Experiment Station, Ames IA. Project No. 2143.     

Effects of dietary triacylglycerol structure on triacylglycerols of resultant chylomicrons from fish oil- and seal oil-fed rats

We investigated the influence of the intramolecular fatty acid distribution of dietary triacyl-sn-glycerols (TAG) rich in n-3 polyunsaturated fatty acids (PUFA) on the structure of chylomicron TAG. Fish oil and seal oil, comparable in fatty acid compositions but with different contents of major n-3 PUFA esterified at thesn-2 position (20:5n-3, 46.6%, and 5.3%; 22:6n-3, 75.5%, and 3.8%, respectively), were fed to rats. Mesenteric lymph was collected and the chylomicrons were isolated by ultracentrifugation. The fatty acid composition of chylomicrons largely reflected the fatty acid composition of the oils administered. The intramolecular fatty acid distributions of the TAG fed were reflected in the chylomicron TAG as the fraction of the total contents observed in thesn-2 position of 20:5n-3 were 23.6 and 13.3%, and of 22:6n-3 were 30.6 and 5.4% for resultant chylomicrons following fish oil and seal oil administration, respectively. Thus, after seal oil administration, significant higher load of n-3 PUFA was esterified in thesn-1,3 positions of chylomicron TAG compared with fish oil administration (P<0.05).     

Production of Human Milk Fat Substitutes by Interesterification of Tripalmitin with Ethyl Oleate Catalyzed by Candida parapsilosis Lipase/Acyltransferase

In human milk fat, the saturated fatty acids, namely palmitic acid, are located at the sn-2 position of triacylglycerols (TAG) while unsaturated fatty acids (e.g. oleic acid) are esterified at position sn-1,3. Thus, sn-1,3-dioleoyl-2-palmitoylglycerol (OPO) is the target TAG to be used as human milk fat substitutes (HMFS) in infant formulas. In this study, the noncommercial recombinant lipase/acyltransferase from Candida parapsilosis (CpLIP2) was immobilized in Accurel MP1000, and used as a biocatalyst for the interesterification of tripalmitin with ethyl oleate in a solvent-free medium, to obtain structured lipids used as HMFS. Different molar ratios (MR) of ethyl oleate to tripalmitin (2:1–8:1) were used. After 4 h reaction at 60°C, about 30 mol% of oleic acid incorporation was already observed for all tested MR. An apparent equilibrium was reached after 8–24 h, with 32–51 mol% final incorporation, increasing with the MR. The incorporation of oleic acid into TAG was compared with the maximum predicted values when a random or a sn-1,3-regioselective biocatalyst was used. The obtained values are consistent with the maximum incorporation expected for a sn-1,3-regioselective enzyme. In fact, the amount of oleic acid at position sn-2 was approximately 15% for all the MR tested, which is explained by the acyl migration phenomenon. CpLIP2 exhibited higher activity than most commercial immobilized lipases (e.g. faster reaction in solvent-free media, low enzyme load, and low MR needed), and showed a recognized sn-1,3 regioselective behavior.     

Absorption of isomeric,palmitic acid-containing triacylglycerols resembling human milk fat in the adult rat

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.     

Stereospecific analysis of TAG from sunflower seed oil

Stereospecific analysis of TAG from a sunflower seed oil of Tunisian origin was performed. The TAG were first fractionated according to chain length and degree of unsaturation by RP-HPLC. The four major diacid- and triacid-TAG fractions were palmitoyldilinoleoyl-glycerol, dioleoyllinoleoylglycerol, oleoyldilinoleoylglycerol, and palmitoyloleoyl-linoleoyl-glycerol, amounting to 7.2, 16.6, 29.5, and 12 mol%, respectively. The TAG of the four fractions were individually submitted to stereospecific analysis, using a Grignard-based partial deacylation, separation of sn-1,2(2,3)-DAG from sn-1,3-DAG by boric acid-impregnated silica gel TLC plates, conversion of the sn-1,2(2,3)-DAG to their 3,5-dinitrophenylurethane (DNPU) derivatives, fractionation of DNPU derivatives by RP-HPLC, resolution of the DNPU-DAG by HPLC on a chiral column, transmethylation of each sn-DNPU-DAG fraction, and analysis of the resulting FAME by GC. The data obtained were used to determine the triacyl-sn-glycerol composition of the main TAG of the oil. Fifteen triacyl-sn-glycerols were identified and quantified, representing, along with the monoacid-TAG, trilinoleoylglycerol and trioleoylglycerol, more than 90% of the total oil TAG. The two major triacyl-sn-glycerols were trilinoleoyl-glycerol and 1-linoleoyl-2-linoleoyl-3-oleoyl-glycerol (18.6 and 18.5% of the total, respectively). Results clearly identified linoleic acid as the major FA at the sn-2 position, whereas oleic and palmitic acids were the major FA at the sn-3 position. The sn-1 position was occupied to nearly the same extent by linoleic and oleic acids, and to a greater extent by palmitic acid, which was practically absent at the sn-2 position.     

Acylglycerol structure of genetic varieties of peanut oils of varying atherogenic potential

Detailed investigation was made of the triacylglycerol structure of three varieties of peanut oils of varying atherogenic activity. By means of chromatographic and stereospecific analyses, it was shown that all the oils had markedly nonrandom enantiomeric structures with the long chain saturated fatty acids (C₂₀−C₂₄) confined exclusively to thesn-3-position, whereas the palmitic and oleic acids were distributed about equally between thesn-1-andsn-3-positions, with the linoleic acid being found preferentially in thesn-2-position. On the basis of detailed studies of the molecular species of the separatesn-1,2-,sn-2,3- andsn-1,3-diacylglycerol moieties, it was concluded that the fatty acids in the three positions of the glycerol molecule are combined with each other solely on the basis of their relative molar concentrations. As a result, it was possible to calculate the composition of the molecular species of the peanut oil triacylglycerols (including the content of the enantiomers and the reverse isomers) by means of the 1-random 2-random 3-random distribution. In general, the three peanut oils possessed triacylglycerol structures which where closely similar to that derived earlier for a commercial peanut oil of North American origin. Since their oil has exhibited a high degree of atherogenic potential, it was anticipated that the present oils would likewise be atherogenic, which has been confirmed by biological testing. However, there are certain differences in the triacylglycerol structures among these oils, which can be correlated with the variations in their atherogenic activity. The major differences reside in the linoleic/oleic acid ratios in the triacylglycerols, especially in thesn-2-position, and in the proportions in which these acids are combined with the long chain fatty acids. On the basis of the characteristic structures identified in the earlier analyzed atherogenic peanut oil, the peanut oil of South American origin would be judged to possess the greatest atherogenic potential and this has been borne out by biological testing.     

Analysis of low erucic acid turnip rapeseed oil (Brassica campestris) by negative ion chemical ionization tandem mass spectrometry. A method giving information on the fatty acid composition in positionssn-2 andsn-1/3 of triacylglycerols

A tandem mass spectrometric method is described for the rapid analysis of fatty acid combinations in mixtures of triacylglycerols. Triacylglycerols were introduced into a triple quadrupole mass spectrometervia a direct exposure probe and deprotonated using ammonia negative ion chemical ionization. Collisionally activated spectra were obtained and the resulting fragments used to identify the fatty acid constituents, and the fatty acids preferentially located at thesn-2 position of the triacylglycerols. Fourteen major molecular weight species of purified triacylglycerols of a supercritical fluid extract of low erucic acid turnip rapeseed oil (Brassica campestris) were analyzed. The five major combinations of fatty acids comprised two thrids of the total triacylglycerols and contained oleic, linoleic and α-linolenic acids with linoleic acid favoring thesn-2 position.     

Triacylglycerols of Apiaceae seed oils: Composition and regiodistribution of fatty acids

Oils from the seeds of caraway (Carum carvi), carrot (Daucus carota), celery (Apium graveolens) and parsley (Petroselinum crispum), all from the Apiaceae family, were analyzed by gas chromatography for their triacylglycerol (TAG) composition and fatty acid (FA) distribution between the sn‐1(3) and sn‐2 positions of TAG. Twenty‐two TAG species were quantified. Glyceryl tripetroselinate was the major TAG species in seed oils of carrot, celery and parsley, with levels ranging from 38.7 to 55.3%. In caraway seed oil, dipetroselinoyllinoleoylglycerol was the major TAG species at 21.2%, while the glyceryl tripetroselinate content was 11.4%. Other TAG species were linoleoyloleoylpetroselinoylglycerol and dipetroselinoyloleoylglycerol. Predominantly, TAG were triunsaturated (72.2–84.0%) with diunsaturates at 14.4–25.9%, and small amounts of monounsaturated TAG. Results for regiospecific analysis showed a non‐random FA distribution in Apiaceae for palmitic, petroselinic, linoleic and oleic acids. Petroselinic acid was predominantly located at the sn‐1(3) position in carrot, celery and parsley seed oils, while it was mainly at the sn‐2 position in caraway seed oil. The distribution of linoleic acid was opposite to that of petroselinic acid. Oleic acid was mostly located at the sn‐2 position, except for caraway, where it was evenly distributed between the sn‐1(3) and sn‐2 positions. Both the saturated FA, palmitic and stearic acid, were located mainly at the sn‐1(3) position. The presence of a high level of tripetroselinin in parsley seed oil (55.3%) makes it a potential source for the production of petroselinic acid.     

Varietal differences in peanut triacylglycerol structure

Stereospecific analysis of triacylglycerols from six peanut varieties showed diversity in percent fatty acid placement. Distribution of the fatty acids among thesn-1,-2 and-3 positions was clearly nonrandom. The percentages of palmitic and stearic acids, generally very low at thesn-2 position, were more predominant at thesn-1 than thesn-3 position. Long chain fatty acids were located almost exclusively at thesn-3 position. Thesn-2 position of all varieties was high in unsaturated fatty acids. Triacyglycerols were sufficiently different to suggest that concentrations of specific triacylglycerol species may vary with variety. Mention of firm names or trade products does not imply that they are endorsed or recommended by the Department of Agriculture over other firms or similar products not mentioned.     

Synthesis of the structured lipid 1,3-dioleoyl-2-palmitoylglycerol from palm oil

Human milk fat contains 20–25% palmitic acid (16∶0) and 30–35% oleic acid (18∶1). More than 60% of the plamitic acid occurs at the sn-2 position of the glycerol backbone. Palm oil is a rich source of both palmitic and oleic acids. The structured lipid 1,3-dioleyl-2-palmitoylglycerol (OPO) is an important ingredient in infant formula. OPO was synthesized from palm oil by a three-step method. In the first step, low-temperature fractionation was applied to palm oil FA, yielding a palmitic acid-rich fraction (87.8%) and an oleic acid-rich fraction (96%). The palmitic acid content was further increased to 98.3% by transforming palmitic acid into ethyl palmitate. In the second step, esterification of ethyl palmitate and glycerol catalyzed by lipase Novozym 435 under vacuum (40 mm Hg) was employed for the synthesis of tripalmitin. Finally, OPO was obtained by the reaction of tripalmitin. Finally, OPO was obtained by the reaction of tripalmitin with oleic acid catalyzed by Lipase IM 60. In this final step, the TAG content in the product acylglycerol mixture was 97%, and 66.1% oleic acid was incorporated into TAG. Analysis of the FA composition at the sn-2 position of TAG showed 90.7 mol% of palmitic acid and 9.3 mol% of oleic acid. OPO content in the product TAG was ca. 74 mol%. Thus, an efficient method was developed for the synthesis of OPO from palm oil.     

Regiospecific Analysis of Shark Liver Triacylglycerols

The liver oils of six shallow-water shark species, silky (Carcharhinus falciformis), thresher (Alopias superciliosus), oceanic whitetip (Carcharhinus longimanus), blue (Prionace glauca), hammerhead (Sphyrna lewini) and salmon (Lamna ditropis) were analyzed with particular attention to the regioisomeric composition of triacylglycerols (TAG). The TAG compositions were analyzed by using an HPLC-evaporative light scattering detector and each molecular species identified by HPLC-atmospheric pressure chemical ionization/mass spectrometry. Major lipid components of all sharks’ oils were TAG (~80 %) made up of omega-3 polyunsaturated fatty acids at 26–40 % and 20–25 % docosahexaenoic acid (DHA). Forty different molecular species were detected in the TAG fractions. TAG consisting of one palmitic acid, one DHA and one oleic acid (12.5–19.9 %) and TAG consisting of two palmitic acids and one DHA (8.4–15.4 %) were the predominant form while 30–50 % TAG molecular species were bound to one or more DHA. Distribution of fatty acids in the primary (sn-1 and sn-3) and secondary (sn-2) position of the glycerol backbones was examined by regiospecific analysis by using pancreatic lipase and it was found that DHA was preferentially positioned at sn-2. These findings greatly extend the utilization of shark liver oils in food productions and may have a significant impact on the future development of the fish oil industry.     

Evidence that palmitic acid is absorbed assn-2 monoacylglycerol from human milk by breast-fed infants

Milk fatty acids consist of about 20–25% palmitic acid (16∶0), with about 70% of 16∶0 esterified to thesn-2 position of the milk triacylglycerols. Hydrolysis of dietary triacylglycerols by endogenous lipases producessn-2 monoacylglycerols and free fatty acids, which are absorbed, reesterified, and then secreted into plasma. Unesterified 16∶0 is not well absorbed and readily forms soaps with calcium in the intestine. The positioning of 16∶0 at thesn-2 position of milk triacylglycerols could explain the high coefficient of absorption of milk fat. However, the milk lipase, bile salt-stimulated lipase, has been suggested to complete the hydrolysis of milk fat to free fatty acids and glycerol. These studies determined whether 16∶0 is absorbed from human milk assn-2 monopalmitin by comparison of the plasma triacylglycerol total andsn-2 position fatty acid composition between breast-fed and formula-fed term gestation infants. The human milk and formula had 21.0 and 22.3% of 16∶0, respectively, with 54.2 and 4.8% 16∶0 in the fatty acids esterified to the 2 position. The plasma triacylglycerol total fatty acids had 26.0±0.6 and 26.2±0.6% of 16∶0, and thesn-2 position fatty acids had 23.3±3.3 and 7.4±0.7% of 16∶0 in the three-month-old exclusively breast-fed (n=17) and formula-fed (n=18) infants, respectively. Marked differences were found in the plasma total and the 2 position phospholipid percentage of 20∶4ω6, i.e., 11.6±0.3 and 6.9±0.6 (total), 17.7±1.4 and 9.7±0.6 (sn-2 position) and percentage of 22∶6ω3, 4.6±0.3 and 2.1±0.3 (total), 5.6±0.6 and 2.0±0.2 (sn-2 position) for the breast-fed and formula-fed infants, respectively. These studies provide convincing evidence that 16∶0 is absorbed from human milk assn-2 monoacyl-glycerol. The metabolic significance of the differences in positional distribution of fatty acids in the plasma lipids of breast-fed and formula-fed infants is not known.     

Postparturition changes in the triacylglycerols of cow colostrum

The changes in the triacylglycerol (TAG) composition of colostrum fat of three cows were studied. In addition to the determination of fatty acid composition by gas chromatography, the distribution of TAG according to the acyl carbon number (ACN) and molecular weight was analyzed utilizing both supercritical fluid chromatography (SFC) and ammonia negative-ion chemical ionization mass spectrometry (MS). Colostrum TAG contained substantially less stearic and oleic acids and more myristic and palmitic acids than the normal Finnish milk fat. The major trends in the changes of fatty acids and TAG were similar for each cow, although clear differences between individuals were found. During the first week of parturition, the proportions of short-chain fatty acids (C₄–C₁₀) typically increased as well as those of stearic and oleic acids, whereas the relative amounts of C₁₂–C₁₆ acids decreased, especially those of myristic and palmitic acids. Distinct changes occurred also in TAG distributions: the proportions of molecules with ACN 38–40 increased and those with ACN 44–48 decreased. Although there were distinct differences between individuals shortly after delivery, both the fatty acid compositions and TAG distributions of the milk samples of the cows started to resemble each other after one week. The theoretical profiles of colostrum TAG calculated based on the fatty acid compositions differed clearly from the ACN distributions analyzed by SFC and MS. Thus, the analysis of TAG is essential, because the changes in molecular species composition of colostrum TAG cannot be estimated according to the fatty acid analysis alone.     

Composition and distribution of individual molecular species of major glycolipids in wheat flour

The distribution of individual molecular species of the main wheat flour glycolipids, digalactosyldiglyceride (DGDG), monogalactosyldiglyceride (MGDG), digalactosylmonoglyceride (DGMG) and monogalactosylmonoglyceride (MGMG) has been investigated by reversed phase high-performance liquid chromatography of their benzoate derivatives after the respective galactosylglyceride classes were obtained by semi-preparative high-performance liquid chromatography. Combinations of linoleic acid at thesn-2 position with linoleic, oleic and palmitic acids at thesn-1 position predominated as major common molecular species of MGDG and DGDG. The pairs 16:0/20:4, 18:3/20:1, 18:0/18:3, 18:0/18:1 and 20:0/18:2 were determined only among MGDG molecular species. Five common molecular species containing 16:0, 18:0, 18:1, 18:2 and 18:3 fatty acids, respectively, were determined in MGMG and DGMG, with 18:2 being the most predominant form, and 18:1 (MGMG) and 16:0 (DGMG) as the next major fatty acids.