Direct inlet negative ion chemical ionization tandem mass spectrometric analysis of triacylglycerol regioisomers in human milk and infant formulas

Analysis of triacylglycerol regioisomers in plant oils using direct inlet negative ion chemical ionization tandem mass spectrometry

Triacylglycerols (TGs) are the primary lipids of plant oils and the positional distribution of fatty acids (FAs) is essential to physicochemical, functional, and nutritional qualities of oils. Most studies have reported TG species in plant oils. In some studies, FA combinations in each TG species have been reported still neglecting the regioisomer composition of TGs. In this study, a fast direct inlet negative ion chemical ionization tandem mass spectrometric (NICI-MS/MS) method and optimization algorithm were applied to study the regioisomerism of TGs in 18 different plant oils. According to FA composition results, oleic, FA 18:1(9); linoleic, FA 18:2(9,12); palmitic, FA 16:0 and stearic acid, FA 18:0 were the most abundant FAs, composing mainly TG species having acyl carbon numbers 50, 52 and 54 and 1-4 double bonds. Based on 35 detected TG species, oils were classified into five groups using clustering analysis. Each group had a different dominant TG species of which the most abundant were triunsaturated ones. In regioisomeric pairs or triplets, FA 16:0, FA 16:1(9), FA 18:0, and FA 18:2(9,12) were more commonly in the sn-1/3 position, while FA 18:1 slightly preferred sn-2. The most abundant TG regioisomers were: TG 16:0_18:1(sn-2)_18:1 (52:2, mainly 18:1 in sn-2) especially in avocado, macadamia nut, olive, and palm oils; TG 18:2_18:2(sn-2)_18:1 and TG 18:2_18:1(sn-2)_18:2 (TG 54:5, mainly 18:2 in sn-2) in corn, pumpkin seed, sesame, and sunflower oils. The use of high-throughput NICI-MS/MS method to study regioisomers in commercial plant oils contributes to further studies on profiling lipid structure and developing products with specific TG compositions to meet dietary needs. The regiospecific information of TGs in edible oils is crucial for understanding their health benefits and functional properties, which are in turn needed in selecting oils for various applications.

Lipase-mediated human milk fat substitute production: Mechanistic insights and a rational synthesis strategy

1,3-dioleoyl-2-palmitoylglycerol (OPO) and 1-oleoyl-2-palmitoyl-3-linoleoylglycerol (OPL) are two essential types of human milk fat substitutes (HMFS). Their unique fatty acid composition and distribution play a significant role in promoting infant health, making the reaction conversion and acyl migration critical factors for developing efficient preparation methods. Promoting the conversion of the substrate while simultaneously inhibiting acyl migration is crucial for obtaining the desired HMFS products. In this study, we comparatively investigated enzymatic acidolysis and transesterification for HMFS production and revealed enzymatic kinetics as well as acyl migration mechanism during the process. Acyl migration was observed through the lipase-catalyzed mechanism, and the associated free energy changes were analyzed using density functional theory (DFT). The presence of long-chain fatty acids in the synthesis system resulted in intermediates with higher relative free energy during acyl migration. Based on these findings, we propose a novel synthesis strategy consisting of multi-step transesterification and dry fractionation, leveraging the differences in freezing points to minimize acyl migration. The resulting OPO product contains 90.42% oleic acid specifically at the sn-1,3 positions, highlighting its potential application in infant formulas. This study presents a systematic investigation of the kinetics and mechanisms involved in lipase-mediated HMFS production, providing valuable insights for rational synthesis approaches.

Progress in triacylglycerol isomer detection in milk lipids

In triacylglycerols (TAGs), position differences of fatty acids on the glycerol skeleton produce various TAG isomers. These TAG isomers have different pathways of digestion, absorption, and utilization in infants, thereby affecting TAG nutritional properties of TAGs. Here, we review the progress of research on methods for detecting TAG isomers, and identify direction and thought for improving these methods, including novel chromatographic combinations, perfect algorithm, and improved equipment. The ensuing optimization of these methods is expected to provide robust guarantee for the gradual improvement of milk-derived TAG isomer detection, and is an important prerequisite for infant formula to mimic the structured lipids of human milk.

Advanced Tandem Mass Spectrometric Analysis of Complex Mixtures of Triacylglycerol Regioisomers: A Case Study of Bovine Milk Fat

Comprehensive analysis of triacylglycerol (TAG) regioisomers is extremely challenging, with many variables that can influence the results. Previously, we reported a novel algorithmic method for resolving regioisomers of complex mixtures of TAGs. In the current study, the TAG Analyzer software and its mass spectrometric fragmentation model were further developed and validated for a much wider range of TAGs. To demonstrate the method, we performed for the first time a comprehensive analysis of TAG regioisomers of bovine milk fat, a very important and one of the most complex TAG mixtures in nature containing FAs ranging from short to long carbon chains. This analysis method forms a solid basis for further investigation of TAG regioisomer profiles in various natural fats and oils, potentially aiding in the development of new and healthier foods and nutraceuticals with targeted lipid structures.

Detection and analysis of triacylglycerol regioisomers via electron activated dissociation (EAD) tandem mass spectrometry

Triacylglycerols (TGs) are important components of human diet. The positional distribution of fatty acids (FAs) on the glycerol backbone affects the chemistry and physical properties of fats. Especially for infants, the structure of TGs plays an important role in the growth and development. However, limited by detecting technology, accurately identifying regioisomers of ABA/AAB and BAC/ABC/ACB type TGs is a significant challenge for human milk utilization and the development of infant formula. For this, we exploit a novel method for identifying the regioisomers of ABA/AAB and BAC/ABC/ACB type TGs within complex lipid mixtures, via used electron activated dissociation (EAD) tandem mass spectrometry. The distribution information of acyl chains at the sn-2 and sn-1/3 positions of glycerol backbone and double bonds in unsaturated FAs can be easily obtained by fragmenting TG ions with energetic electrons (15 eV). Then, the standard curve was established by correlating the peak area intensity of sn-2 characteristic product ion with the content of TG regioisomers standard. These analytical methods successfully enabled the identification and quantification of TG regioisomers in human milk, cow milk, infant formula, palm oil, and sunflower oil. Additionally, the distribution of the double-bond positions of unsaturated FAs in these samples was also identified. Compared to traditional methods, this approach eliminates the need for complex processing and analysis procedures, enabling rapid structural characterization of ABA/AAB and BAC/ABC/ACB type TGs within 17 min. Hence, we provide a rapid and convenient methodology for detecting and analyzing ABA/AAB and BAC/ABC/ACB type TG regioisomers, thereby offering valuable assistance in the development of specialized formulations and facilitating effective process control for ensuring the quality of edible oils and fats.

3-Monochloropropane-1,2-diol reduced bioaccessibility of sn-2 palmitate via binding with pancreatic lipase in infant formula during gastrointestinal digestion

Infant formula contains 3-monochloropropane-1,2-diol esters (3-MCPDE), which are formed during the deodorization step of vegetable oil refining. The European Food Safety Authority stated that 3-MCPDE can be hydrolyzed in the gastrointestinal tract to free-form 3-monochloropropane-1,2-diol (3-MCPD), which has potential toxicity and can be rapidly absorbed. Evaluating the effect of 3-MCPD on nutrition absorption is a prerequisite for establishing effective management strategies. A total of 66 crucial lipid molecules associated with 3-MCPD were identified based on debiased sparse partial correlation analysis. 3-MCPD affected triglyceride hydrolyzation and increased the concentration of undigested sn-2 palmitate (9.57 to 17.06 mg kg-1). 3-Monochloropropane-1,2-diol reduced the bioaccessibility of fatty acids, and more short- (31.42 to 58.02 mg kg-1) and medium-chain fatty acids (17.03 to 26.43 mg kg-1) remained unabsorbed. Lipidomic profiles of infant formula models spiked with different 3-MCPDE levels were investigated, and the results were consistent with the experiments with the commercial formula indicating lipid alteration was mainly affected by the digestive 3-MCPD. The formation of 3-MCPD ester-pancreatic lipase with the binding energy of -4.9 kcal mol-1 was more stable than triglyceride-pancreatic lipase (-4.0 kcal mol-1), affecting triglyceride hydrolyzation. 3-Monochloropropane-1,2-diol was bound to Glu13 and Asp331 residues of the pancreatic lipase via hydrogen bonds, which resulted in a conformational change of pancreatic lipase and spatial shielding effect. The existence of the spatial-shielding effect reduced the accessibility of pancreatic lipase and further affected triglyceride hydrolyzation. These findings indicated that 3-MCPD obstructed nutrient acquisition and laid the foundation for the subsequent nutrition enhancement design.

Metabolic fate of DHA from regio- and stereospecific positions of triacylglycerols in a long-term feeding trial in rats

This study investigated the impact of regio- and stereospecific position of docosahexaenoic acid (DHA) in dietary triacylglycerols (TAGs) on the fatty acid composition of tissues and organs in rats. Four-week feeding with TAGs containing DHA in sn-1, 2, or 3 position and palmitic acid in the remaining positions at a daily dosage of 500 mg TAG/kg body weight significantly increased the DHA content in all organs and tissues in rats, except in the brain, where the change in DHA level was not statistically significant. The group fed sn-1 DHA showed a significantly higher content of DHA in the plasma TAG than the group fed sn-3 DHA. The sn-3 DHA group had higher levels of DHA in the visceral fat compared to the sn-1, sn-2, as well as all other groups. This is the first study showing that DHA from sn-1 and sn-3 positions of dietary TAGs have differential accumulation in tissues. The new findings improved the current knowledge on the significance of TAG isomeric structure for the bioavailability and metabolic fate of DHA.

Effects of lipids from multiple sources on glyceride composition, concentration, and structure of infant formulas benchmarked to human milk

The important parameters affecting the nutritional properties of lipids were analyzed and compared between human milk (HM), infant formulas (IFs), mammalian milk, and substitute fat, including molecular species, fatty acid composition, glyceride content, and important structural triacylglycerols (TAGs). The molecular species of triacylglycerols with functional fatty acids were significantly different between HM and IFs, and their contents in HM were significantly higher than those in IFs. Accordingly, the evaluation scores of fatty acid composition and glyceride content in IFs were less than 50 compared to HM. Although the introduction of vegetable oils effectively improved the unsaturation of IF lipid, the excessive addition of TAGs rich in oleic and linoleic acid resulted in an imbalance of TAG composition and structure. Only 36.84 % of IFs were supplemented with structured lipids, but those still lacked sn-2 palmitate TAGs. The adoption of multiple lipids and novel processing technologies is required for novel IFs to match the composition, content, positional structure and spherical membrane structure of HM as closely as possible.

Comparison of Workflows for Milk Lipid Analysis: Phospholipids

Milk is a rich source of lipids, with the major components being triglycerides (TAG) and phospholipids (mainly phosphatidylcholine (PC), sphingomyelin (SM), phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylinositol (PI)). Liquid chromatography-mass spectrometry (LC-MS) is the predominant technique for lipid identification and quantification across all biological samples. While fatty acid (FA) composition of the major lipid classes of milk can be readily determined using tandem MS, elucidating the regio-distribution and double bond position of the FA remains difficult. Various workflows have been reported on the quantification of lipid species in biological samples in the past 20 years, but no standard or consensus methods are currently available for the quantification of milk phospholipids. This study will examine the influence of several common factors in lipid analysis workflow (including lipid extraction protocols, LC stationary phases, mobile phase buffers, gradient elution programmes, mass analyser resolution and isotope correction) on the quantification outcome of bovine milk phospholipids. The pros and cons of the current LC-MS methods as well as the critical problems to be solved will also be discussed.

Triacylglycerol regioisomers containing palmitic acid analyzed by ultra-performance supercritical fluid chromatography and quadrupole time-of-flight mass spectrometry: Comparison of standard curve calibration and calculation equation

Triacylglycerol (TAG) regioisomers containing palmitic acid (16:0) was identified using ultra-performance supercritical fluid chromatography and quadrupole time-of-flight mass spectrometry (UPSFC-Q-TOF-MS) and quantified using calibration curve method and calculation equation method. There were negative linear correlation between [R_A-A]⁺/[R_A-A]⁺+[R_A-B]⁺ and content of sn-A-B-A (%) for AAB/ABA type TAGs, [R_{sn-1 FA-sn-3 FA}]⁺/[R_B-C]⁺+[R_A-C]⁺+[R_A-B]⁺ and content of fatty acid (FA) at sn-2 position (%) for BAC/ABC/ACB type TAGs. The difference between calculation equation and standard curve method was acceptable. The TAG regioisomers in human milk, mammalian milk, lard and fish oil were identified and quantified using the developed methods. This study provided a reliable and facile method for analysis of the TAG regioisomers, which was capable of the selection of oil materials for infant formula production.

Medium- and long-chain triacylglycerols and di-unsaturated fatty acyl-palmitoyl-glycerols in Chinese human milk: Association with region during the lactation

The triacylglycerols (TAGs) of medium- and long-chain triacylglycerols (MLCT) and di-unsaturated fatty acyl-palmitoyl-glycerols (UPU) in human milk provide better nutritional effects, and should be prioritized as crucial focuses on neonatal nutrition research. However, little has been done on the influences of the lactation stage and regional diversity on MLCT and UPU. In this study, we collected 204 human milk samples during colostrum, 1st and 4th month from the north (Baotou), central (Beijing), east (Jinan), southwest (Kunming), southeast (Shenzhen), and northwest (Xining) regions of China. There were 122 species of TAGs detected with UPLC-Q-TOF-MS, including 60 kinds of MLCT and 15 kinds of UPU. The MLCT and UPU type TAGs in human milk were ~27 and ~38%, respectively. The sum content of MLCT and UPU in human milk was stable. Compared to the regional diversity, lactation stages showed more obvious influences on MLCT and UPU composition. Moreover, a summary of TAG studies indicated that Chinese human milk showed a higher ratio of O-P-L to O-P-O than in western countries.

Profiling of triacylglycerol composition in the breast milk of Chinese mothers at different lactation stages

Triacylglycerol (TAG) is the primary constituent of human milk fat and plays a vital role in the healthy development of infants. But few studies reported the sophisticated profile of TAG molecular species in human breast milk and its temporal changes during a prolonged lactation period. An efficient ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method was adopted to examine TAGs. A total of 128 TAGs in 296 human breast milk samples collected during postnatal 0 to 400 days were identified. The changes in the human milk TAG profile mainly took place in the early stages of lactation (postnatal 0-45 days), and the TAG profile became stable in mature milk after 200 days of lactation. Odd chain fatty acids (OC-FAs) may be important markers for identifying human breast milk of different lactation stages. This study could provide evidence for developing safe and efficacious human-milk substitutes for children without access to human breast milk.

Role Medium-Chain Fatty Acids in the Lipid Metabolism of Infants

Human breastmilk, the ideal food for healthy infants, naturally contains a high concentration of medium-chain fatty acids (MCFAs, about 15% of total fatty acids). MCFAs are an important energy source for infants due to their unique digestive and metabolic properties. MCFA-enriched oils are widely used in an infant formula, especially the formula produced for preterm infants. Recently, there has been a growing interest in the triglyceride structure of MCFAs in human milk, their metabolism, and their effects on infant health. This study summarized the MCFA composition and structure in both human milk and infant formula. Recent studies on the nutritional effects of MCFAs on infant gut microbiota have been reviewed. Special attention was given to the MCFAs digestion and metabolism in the infants. This paper aims to provide insights into the optimization of formulations to fulfill infant nutritional requirements.

Advances in analysis, metabolism and mimicking of human milk lipids

Human milk lipids differ from the milk lipids of other mammals in composition and positional distribution of fatty acids. Analysis and detection technology of lipids is key to understanding milk lipids, and thus the concentrations, compositions and distribution characteristics of milk lipids are discussed. Differences between human milk lipids and their substitutes in form, composition and structure affect their digestion, absorption and function in infants. Characteristics and mimicking of human milk lipids have been intensively studied with the objective of narrowing the gap between human milk and infant formulae. Based on the existing achievements, further progress may be made by improving detection techniques, deepening knowledge of metabolic pathways and perfecting fat substitutes. This review detailed the characteristics of human milk lipids and related detection technologies with a view towards providing a clear direction for research on mimicking human milk lipids in formulae to further improve infant nutrition.

Similarity Index for the Fat Fraction between Breast Milk and Infant Formulas

The similarity of the fat fraction in infant formulas rich in either bovine milk fat (MF) or vegetable oil (VO) to breast milk was evaluated by analyzing their lipid composition. Milk fat-rich formulas were highly similar (average similarity index 0.68) to breast milk compared to the VO-rich formulas (average similarity index 0.56). The highest difference in the indices was found in the contents of cholesterol (0.66 vs 0.28 in MF- and VO-rich formulas, respectively, on average) and polar lipids (0.84 vs 0.53), the positional distribution of fatty acids in the sn-2 position of triacylglycerols (0.53 vs 0.28), and fatty acid composition (0.72 vs 0.54). The VO-based formulas were superior in similarity in n - 6 PUFA. Thus, the addition of bovine MF fractions is an effective way to increase the similarity between the lipid composition of infant formulas and human milk.

Ammonia Concentration in the Eluent Influences Fragmentation Pattern of Triacylglycerols in Mass Spectrometry Analysis

Correct assessment of the fatty acyl at the glycerol sn-2 position in triacylglycerol (TAG) analysis by liquid chromatography and mass spectrometry (LC-MS) is challenging. Ammonium hydroxide (NH₄OH) is the preferred choice for the solvent additive for the formation of the ammonium adduct ([M + NH₄]⁺). In this study, the influence of different NH₄OH concentrations in the eluents on TAG adduct formation and fragmentation under LC-MS analysis was assessed. Increasing NH₄OH concentrations delayed the chromatographic elution time according to a power function. The [M + NH₄]⁺ and [M + ACN + NH₄]⁺ adducts (where ACN means acetonitrile) were formed at all ammonium concentrations assayed. [M + ACN + NH₄]⁺ predominated above 18.26 mM [NH₄OH], and the intensity of [M + NH₄]⁺ dropped. TAG fragmentation for fatty acyl release in the MS^E was reduced with increasing [M + ACN + NH₄]⁺ adduct, which suggests that ACN stabilizes the adduct in a way that inhibits the rupture of the ester bonds in TAGs. A linear equation (H_sn-I = a × H_[M+NH4]+, where sn-I refers to the sn position of the glycerol (I = 1, 2, or 3) and H is the peak height) was deduced to quantify the dehydroxydiacylglycerol fragment intensity in relation to [M + NH₄]⁺ intensity in the full scan. This equation had a slope mean value of 0.369 ± 0.058 for the sn-1 and sn-3 positions, and of 0.188 ± 0.007 for the sn-2 position.

Pinpointing Alkane Chain Length, Saturation, and Double Bond Regio- and Stereoisomers by Liquid Interfacial Plasmonic Enhanced Raman Spectroscopy

The lipids with a rich diversity of isomers face a formidable challenge in comprehensive structural analysis. The commonly used mass spectrometry-based techniques usually require a considerable number of molecules with sophisticated chemical derivatization or ion mobility separation, but the co-existing of structurally similar isomers often makes the distinction impossible. Here, we develop an alternative powerful liquid/liquid interfacial surface-enhanced Raman spectroscopy (SERS) strategy at normal temperature and pressure without any sources of ionization or radiation. This strategy generates high-resolution fingerprints in molecular chain length, C═C position, saturation, and regio- and stereoisomers of both glycerides and fatty acids and requires only trace amounts of molecules down to 1 ppb to achieve discrimination and exhibits great potentials to push the identification capability to trace levels or even the single-molecule level. According to experimental data and theoretical simulations, these targets have the amphiphilic and emulsifying properties, exhibit ordered molecular orientation and adsorption patterns, promote the co-assembly with plasmonic nanoarrays at the immiscible liquid/liquid interface, and consequently amplify the detection sensitivity. As a contrast, the typical SERS based on solid/air interfacial plasmonic nanoarrays faces the intrinsic bottleneck of extremely weak intensity and indistinguishable spectral fingerprints of lipid molecules. The vibrational fingerprints exhibit a rich range of well-resolved absorption features that are clearly diagnostic for fine structural changes and pave a new way for straightforward measurement without laborsome sample purification, enrichment, or complex derivatization. Although challenging, its unprecedented resolving power expands the potentials of SERS, serving as an ultimate analytical method to provide insights into the detailed structural features of other lipids under facile conditions in the future.

Regio- and Stereospecific Analysis of Triacylglycerols—A Brief Overview of the Challenges and the Achievements

The efforts to reveal, in detail, the molecular and intramolecular structures of one of the main lipid classes, namely, triacyl-sn-glycerols, which are now known to affect their specific and important role in all living organisms, are briefly overviewed. Some milestones of significance in the gradual but continuous development and improvement of the analytical methodology to identify the triacylglycerol regio- and stereoisomers in complex lipid samples are traced throughout the years: the use of chromatography based on different separation principles; the improvements in the chromatographic technique; the development and use of different detection techniques; the attempts to simplify and automatize the analysis without losing the accuracy of identification. The spectacular recent achievements of two- and multidimensional methods used as tools in lipidomics are presented.

Comparative Analysis of Triglycerides From Different Regions and Mature Lactation Periods in Chinese Human Milk Project (CHMP) Study

The kinds and proportions of triglycerides of human mature milk play an independent role in the growth of infants. In this study, the human milk samples obtained from eight different Chinese cities (Chengdu, Weihai, Lanzhou, Jinhua, Beijing, Guangzhou, Zhengzhou, and Harbin) and six sequential mature lactation times (30, 60, 90, 120, 150, and 180 days) were detected for the triglycerides. The result demonstrated that total 66 triglycerides were detected in mature human milk, with acyl carbon number (ACN) numbers were locating in the range of 34–54 and double bond (DB) numbers were locating in the range of 0–6. In addition, the percentage of OPO, OPL, and OOO was relatively higher than others, accounted for more than 4% of total triglycerides in all the lactation areas and times, and the percentage of U2S and LLL triglycerides was also richest in mature milk. Furthermore, it was obvious that lactation regions had more significant effect on the triglycerides compared with lactation time and the triacylglycerols (TAGs) of human milk in Guangzhou were clearly different from that in other regions. Therefore, the results of this study will provide data reference for the design of infant formula suitable for Chinese babies.

Bovine Milk Triacylglycerol Regioisomer Ratio Shows Remarkable Inter-Breed and Inter-Cow Variation

Regioisomers (or positional isomers) of triacylglycerols (TAGs) of milk are known to show differential outcome in relation to human absorption. Quantitation of TAG regioisomers remains a big challenge due to the lack of facile chromatographic separation technique. The feasibility of using fragment ion intensity ratio to determine the ratio of co-eluting AAB/ABA-type regioisomer pairs was confirmed in this study. The ability of C30 stationary phase in resolving interfering TAG isomers was demonstrated for the first time. This allowed us to reveal the complexity of using fragment ion intensity to quantify 1,2-olein-3-palmitin (OOP), 1,3-olein-2-palmitin (OPO), 1,2-olein-3-stearin (OOS), and 1,3-olein-2-stearin (OSO) regioisomers in milk samples. A novel algorithm was proposed to consider the contribution of OPO/OOP and OSO/OOS double bond (DB)-isomers and to eliminate the interference of isobaric ions from other isomers, an aspect overlooked in previous studies. This liquid chromatography-mass spectrometry method that requires no pre-fractioning and a moderate chromatographic separation time of 36 min is simple and, thus, suitable for screening a large number of samples for genetic analysis of this trait. Preliminary results using a small cohort of animals showed that OPO/OOP ratio differs significantly between Jersey and Holstein cows, and a large variation was also observed across individual Holstein cows.

Strategy for stereospecific characterization of natural triacylglycerols using multidimensional chromatography and mass spectrometry

Stereoisomeric determination of individual triacylglycerols (TAGs) in natural oils and fats is a challenge due to similar physicochemical properties of TAGs with different fatty acid combinations. In this study, we present a strategy to resolve the enantiomeric composition of nutritionally important TAGs in sea buckthorn (Hippophaë rhamnoides) as an example food matrix. The targeted strategy combines 1) fatty acid profiling with GC, 2) separation of TAGs with RP-HPLC, 3) stereospecific separation with chiral-phase HPLC and 4) structural characterization with MS. Three major asymmetric diacid- and triacid-TAG species were analyzed in sea buckthorn pulp oil. Off-line coupling of RP-HPLC and chiral-phase HPLC allowed separation of several TAG regioisomers and enantiomers, which could not be resolved using one-dimensional techniques. Enantiomeric ratios were determined and specific structural analysis of separated TAGs was performed using direct inlet ammonia negative ion chemical ionization method. Of the TAG 16:0/16:1/16:1 palmitic acid (C16:0) was located predominantly in a primary position and the enantiomeric ratio of TAG sn-16:1-16:1-16:0 to sn-16:0-16:1-16:1 was 70.5/29.5. Among the TAGs 16:0/16:0/18:2 and 16:0/16:0/16:1, only ca 5% had C16:0 in the sn-2 position, thus, ca 95% were symmetric sn-16:0-18:2-16:0 and sn-16:0-16:1-16:0. The enantiomeric ratio of triacid-TAGs containing C16:0 and two unsaturated fatty acids (palmitoleic C16:1, oleic C18:1 or linoleic acids C18:2) could not be resolved due to lack of commercial enantiopure reference compounds. However, it became clear that the targeted strategy presented offer unique and convenient method to study the enantiomeric structure of individual TAGs.