Chemical profiling of triacylglycerols and diacylglycerols in cow milk fat by ultra-performance convergence chromatography combined with a quadrupole time-of-flight mass spectrometry

Characterization of lipid composition and nutritional quality of yak ghee at different altitudes: A quantitative lipidomic analysis

Efficient and comprehensive analysis of lipid profiles in yak ghee samples collected from different elevations is crucial for optimal utilization of these resources. Unfortunately, such research is relatively rare. Yak ghee collected from three locations at different altitudes (S2: 2986 m; S5: 3671 m; S6: 4508 m) were analyzed by quantitative lipidomic. Our analysis identified a total of 176 lipids, and 147 s lipid of them were upregulated and 29 lipids were downregulated. These lipids have the potential to serve as biomarkers for distinguishing yak ghee from different altitudes. Notably, S2 exhibited higher levels of fatty acids (21:1) and branched fatty acid esters of hydroxy fatty acids (14:0/18:0), while S5 showed increased levels of phosphatidylserine (O-20:0/19:1) and glycerophosphoric acid (19:0/22:1). S6 displayed higher levels of triacylglycerol (17:0/20:5/22:3), ceramide alpha-hydroxy fatty acid-sphingosine (d17:3/34:2), and acyl glucosylceramides (16:0-18:0-18:1). Yak ghee exhibited a high content of neutralizing glycerophospholipids and various functional lipids, including sphingolipids and 21 newly discovered functional lipids. Our findings provide insights into quantitative changes in yak ghee lipids during different altitudes, development of yak ghee products, and screening of potential biomarkers.

Detection of walnut oil adulterated with high-linoleic acid vegetable oils using triacylglycerol pseudotargeted method based on SFC-QTOF-MS

Authentication of walnut oil (WO) is challenging due to the adulteration of high-linoleic acid vegetable oils (HLOs) with similar fatty acid composition. To allow the discrimination of WO adulteration, a rapid, sensitive and stable scanning method based on supercritical fluid chromatography quadrupole time-of-flight mass spectrometry (SFC-QTOF-MS) was established to profile 59 potential triacylglycerol (TAGs) in HLOs samples within 10 min. Limit of quantitation of the proposed method is 0.002 µg mL^-1 and the relative standard deviations range from 0.7% to 12.0%. TAGs profiles of WO samples from various varieties, geography origins, ripeness, and processing methods were used to construct orthogonal partial least squares-discriminant analysis (OPLS-DA) and OPLS models that were highly accurate in both qualitative and quantitative prediction at adulteration levels as low as 5% (w/w). This study advances the TAGs analysis to characterize vegetable oils and holds promise as an efficient method for oil authentication.

Analysis of milk with liquid chromatography–mass spectrometry: a review

As a widely consumed foodstuff, milk and dairy products are increasingly studied over the years. At the present time, milk profiling is used as a benchmark to assess the properties of milk. Modern biomolecular mass spectrometers have become invaluable to fully characterize the milk composition. This review reports the analysis of milk and its components using liquid chromatography coupled with mass spectrometry (LC–MS). LC–MS analysis as a whole will be discussed subdivided into the major constituents of milk, namely, lipids, proteins, sugars and the mineral fraction.

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.

Triacylglycerol fingerprint of sow milks during different lactation stages and from different breeds

Sow milk fats not only provide energy but also essential nutrients for piglets. Thus, feeding strategies must be aligned with fat composition, especially triacylglycerols (TAGs) and their isomers. The triacylglycerol (TAG) profiles of sow milk fats from five typical breeds (Landrace × Large White, Landrace, Large White, Duroc, Pietrain) and two lactation stages (colostrum and milk) were systematically studied. A total of 45 major TAG species were identified using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. The most abundant TAG was oleic acid-palmitic acid-linoleic acid (O-P-L) (13.92% and 12.03% in colostrum and milk, respectively), which was not significantly different in colostrum among all breeds. TAG composition of sow milk was affected mainly by the lactation stage rather than sow breed. Furthermore, TAG compositions of sow milk fats were similar to those of human milk fats, but significant differences were observed between commercial piglet formulas and sow milk. Therefore, the results will contribute to the optimization of piglet formulas to improve the growth and wellness of piglets, as well as potentially providing a basis for food usage as a new source of nutrients for human infants in future.

Recent advances in proteomics and metabolomics in plants

Over the past decade, systems biology and plant-omics have increasingly become the main stream in plant biology research. New developments in mass spectrometry and bioinformatics tools, and methodological schema to integrate multi-omics data have leveraged recent advances in proteomics and metabolomics. These progresses are driving a rapid evolution in the field of plant research, greatly facilitating our understanding of the mechanistic aspects of plant metabolisms and the interactions of plants with their external environment. Here, we review the recent progresses in MS-based proteomics and metabolomics tools and workflows with a special focus on their applications to plant biology research using several case studies related to mechanistic understanding of stress response, gene/protein function characterization, metabolic and signaling pathways exploration, and natural product discovery. We also present a projection concerning future perspectives in MS-based proteomics and metabolomics development including their applications to and challenges for system biology. This review is intended to provide readers with an overview of how advanced MS technology, and integrated application of proteomics and metabolomics can be used to advance plant system biology research.

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.

A Comparative Study of Milk Fat Extracted from the Milk of Different Goat Breeds in China: Fatty Acids, Triacylglycerols and Thermal and Spectroscopic Characterization

Goat milk (GM) is an excellent alternative to cow milk and has recently been used in commercial infant formula preparation due to its superior fat composition. Here, the fatty acid (FA) composition, triacylglycerol (TAG) molecular species, thermal behavior and infrared spectra of extracted milk fat from the milk of the two main breeds of dairy goat bred in China (Guanzhong GM (GZG) and Xinong Saanen GM (XSG)) are investigated. Gas chromatography, Fourier-transform infrared spectroscopy, differential scanning calorimetry and ultra-performance convergence chromatography with quadrupole time-of-flight mass spectrometry are applied. The obtained results evidence significant fat compositional differences based on the breed that produced the considered GM. The major FAs in both GM fats were capric (C10:0), myristic (C14:0), palmitic (C16:0), stearic (C18:0) and oleic (C18:1 n-9c). GZG presented a higher content of medium-chain saturated FAs, while XSG had higher unsaturated FAs with higher ratios of L/Ln and n-6/n-3. A total of 339 and 359 TAGs were detected and quantified in GZG and XSG, and the major TAGs were those of m/z 740.6712 (14.10 ± 0.27%) and m/z 684.6094 (10.94 ± 0.02%), respectively. Milk TAGs of GZG and XSG showed 24–54 and 26–54 total acyl carbon numbers with a 0–4 and 0–5 double bond number at 68 and 72 various retention times, respectively. Thermal analysis showed that all GM fat samples melted below normal body temperature. Infrared spectra revealed higher absorption values of GZG milk fat. This study provides valuable information to the dairy industry sector about GM fat produced in China, assessing the appropriateness of Chinese GM fat to be applied in Chinese infant formula.

SWATH-MS2&1: Development and Validation of a Pseudotargeted Lipidomics Method for the Analysis of Glycerol Esters in Milk

Glycerol ester (GE) is a kind of important lipid in milk, which varies greatly depending on many factors. In this study, a novel pseudotargeted lipidomics strategy, named SWATH-MS2&1, was developed for the detection of GEs in milk and the Folch method was selected for the sample preparation. The developed method exhibited a competitive alternative to the acknowledged pseudotargeted strategy, including wider coverage (12 more GEs detected), higher repeatability (12 more GEs, whose coefficient of variation < 0.3), better linearity (5 more GEs, whose R² > 0.8), and similar sensitivity (only 2 GEs less than P-MRM after dilution). SWATH-MS2&1 was applied in the investigation of GEs from different milk samples. The orthogonal partial least-squares difference analysis of 219 GEs identified from SWATH-MS2&1 showed satisfying differentiation of different milk samples, and 76 GEs were screened out as potential markers. Our findings demonstrated that SWATH-MS2&1 could offer an accurate method to measure a wide spectrum of GEs in milk.

Effects of different tempering temperatures on the properties of industrial sheet margarine

Tempering conditions have significant effects on the microstructure, physicochemical properties and application functionalities of ISM.

Triacylglycerol and Fatty Acid Compositions of Blackberry, Red Raspberry, Black Raspberry, Blueberry and Cranberry Seed Oils by Ultra-Performance Convergence Chromatography-Quadrupole Time-of-Flight Mass Spectrometry

The triacylglycerol (TAG) compositions of blackberry, red raspberry, black raspberry, blueberry and cranberry seed oils were examined using ultra-performance convergence chromatography-quadrupole time-of-flight mass spectrometry (UPC²-QTOF MS). A total of 52, 53, 52, 59 and 58 TAGs were detected and tentatively identified from the blackberry, red raspberry, black raspberry, blueberry and cranberry seed oils, respectively, according to their accurate molecular weight in MS1 and fragment ion profiles in MS2. OLL was the most abundant TAG in the blackberry, red raspberry and black raspberry seed oils. Furthermore, the fatty acid compositions of the five berry seed oils were directly determined by gas chromatography coupled with mass spectrometry (GC-MS). In addition, the seed oils had total phenolic contents ranging 13.68–177.06 µmol GAE (gallic acid equivalent)/L oil, and significant scavenging capacities against DPPH, peroxyl, and ABTS⁺ radicals. These results indicated that the combination of UPC² and QTOF MS could effectively identify and semi-quantify the TAGs compositions of the berry seed oils with sn-position information for the fatty acids. Understanding the TAGs compositions of these berry seed oils could improve the utilization of these potentially high nutritional value oils for human health.

Identification and Quantification of Triacylglycerols Using Ultraperformance Supercritical Fluid Chromatography and Quadrupole Time-of-Flight Mass Spectrometry: Comparison of Human Milk, Infant Formula, Other Mammalian Milk, and Plant Oil

Triacylglycerol (TAG) components in human milk during different lactation periods, infant formulas with different fat sources, other mammalian milk (cow, goat, donkey, and yak milk), and plant oil (sunflower, rapeseed, corn, soybean, palm, palm kernel, and coconut oil) were analyzed and compared using ultraperformance supercritical fluid chromatography and quadrupole time-of-flight mass spectrometry (UPSFC-Q-TOF-MS). We identified 191 TAGs (86, 102, 101, and 54 TAGs in human milk, infant formula, mammalian milk, and plant oil, respectively). TAGs esterified with palmitic acid (16:0) were major TAG structures in human milk (59.08% of total TAGs) and contained 30 TAG types. The sn-O/P/O regioisomer constituted more than 80% of the O/P/O content of human milk, whereas the sn-O/O/P levels were higher in other samples. The carbon number (CN) 52 content was higher than the CN 54 content in human milk, with the opposite observed in infant formula. TAGs with CN < 40 content were abundant in cow, goat, and yak milk; donkey milk was rich in CN 52 content. TAGs composed of medium-chain fatty acids (MCFAs) and long-chain fatty acids (LCFAs) were rich in human milk, while TAGs with three MCFAs were rich in infant formula. The TAG characteristics of infant formula were directly related to its fat resource. TAGs with fewer double bonds were abundant in the plant oil formula; however, highly unsaturated TAGs were prominent in the cow and goat milk formulas, similar to plant oil and mammalian milk. Significant differences in the TAG distribution were observed among the different species.

Deep Structural Annotation of Glycerolipids by the Charge-Tagging Paterno-Büchi Reaction and Supercritical Fluid Chromatography-Ion Mobility Mass Spectrometry

Glycerolipids (GLs) are essential for cellular lipid homeostasis, while dysregulation in GL metabolism is often associated with the onset or progression of human-related metabolic diseases. The profile of GLs is thus frequently used as a molecular readout for disease phenotyping. Although mass spectrometry (MS) is the method of choice for GL profiling, the current MS methods are unable to differentiate two major types of structural isomers due to the fact that fatty acyls can be linked to different positions on the glycerol backbone (sn-positions) and the site(s) of unsaturation in acyl chains. Herein, by utilizing charge-tagging Paterno-Büchi (PB) derivatization of carbon-carbon double bond (C═C), supercritical fluid chromatography (SFC), and mobility aligned tandem mass spectrometry (MS/MS), a workflow has been developed for the sensitive and structurally informative analysis of GLs. SFC allows fast separation (within 25 min) of sn-isomers of diacylglycerols (DGs) and separation of triacylglycerols (TGs) of different chain lengths and degrees of unsaturation. Time-aligned parallel fragmentation enables multiple-stage MS/MS of the PB-derivatized lipids in a high-throughput fashion and allows pinpointing C═C location to a specific fatty acyl chain. This workflow reveals the presence of more than 500 molecular structures of neutral lipids from pooled human plasma. A comparison of human plasma samples between type 2 diabetes (N = 7) and control (N = 7) shows significant changes in isomer compositions (C18:1 Δ9 vs Δ11) from nine groups of TG and DG. These findings suggest that the developed workflow can be potentially applied to lipid marker discovery for disease monitoring or diagnosis.

TAILOR-MS, a Python Package that Deciphers Complex Triacylglycerol Fatty Acyl Structures: Applications for Bovine Milk and Infant Formulas

Liquid chromatography tandem mass spectrometry (LC/MS) and other mass spectrometric technologies have been widely applied for triacylglycerol profiling. One challenge for targeted identification of fatty acyl moieties that constitute triacylglycerol species in biological samples is the numerous combinations of 3 fatty acyl groups that can form a triacylglycerol molecule. Manual determination of triacylglycerol structures based on peak intensities and retention time can be highly inefficient and error-prone. To resolve this, we have developed TAILOR-MS, a Python (programming language) package that aims at assisting: (1) the generation of targeted LC/MS methods for triacylglycerol detection and (2) automating triacylglycerol structural determination and prediction. To assess the performance of TAILOR-MS, we conducted LC/MS triacylglycerol profiling of bovine milk and two infant formulas. Our results confirmed dissimilarities between bovine milk and infant formula triacylglycerol composition. Furthermore, we identified 247 triacylglycerol species and predicted the possible existence of another 317 in the bovine milk sample, representing one of the most comprehensive reports on the triacylglycerol composition of bovine milk thus far. Likewise, we presented here a complete infant formula triacylglycerol profile and reported >200 triacylglycerol species. TAILOR-MS dramatically shortened the time required for triacylglycerol structural identification from hours to seconds and performed decent structural predictions in the absence of some triacylglycerol constituent peaks. Taken together, TAILOR-MS is a valuable tool that can greatly save time and improve accuracy for targeted LC/MS triacylglycerol profiling.

Ultra-high performance supercritical fluid chromatography method for separation and quantitation of saikosaponins in herbal medicine

Saikosaponins are the main active ingredients of Bupleuri Radix and have been shown to have hepatoprotective, immunomodulatory and anti-viral activities. Among the saikosaponins, saikosaponin a (SSa), saikosaponin b₁ (SSb₁) and saikosaponin b₂ (SSb₂) are a group of isomers, which are difficult to separate by HPLC. In this study, a new method for separation and quantitation of saikosaponins was established by using ultra-high performance supercritical fluid chromatography (UHPSFC). A Torus Diol column (100 mm × 3 mm, 1.7 μm) was applied in this study. The mobile phase CO₂ (A) was the main solvent with MeOH (B) as co-solvent. The results showed that the five saikosaponins were successfully separated within 22 min through optimization of chromatographic conditions. Besides, the UHPSFC method was applied for the quantitation of saikosaponins in a patent medicine Chaihu Dropping Pills, and demonstrated a good correlation coefficient (R²) ≥ 0.9990 in the range of 0.025 - 0.25 mg/mL. The recoveries of the five saikosaponins at three different concentrations were in the range of 90.23-99.84%. This study indicates that the proposed method has high separation efficiency in analyzing saikosaponins, which provides a new way for the separation and quantitation of saikosaponins in herbal medicines.

Lipophilic extracts isolated from European cranberry bush (Viburnum opulus) and sea buckthorn (Hippophae rhamnoides) berry pomace by supercritical CO2 - Promising bioactive ingredients for foods and nutraceuticals

Lipophilic extracts of Viburnum opulus (VOP) and Hippophae rhamnoides (SBP) berry pomace recovered by supercritical CO₂ (SFE-CO₂) were analysed by UPLC-Q-TOF-MS and GC × GC-TOF for their triacylglycerol, tocopherol, phytosterol and fatty acid composition, while oxidative stability was evaluated by Oxipres and Rancimat methods. SFE-CO₂ recovered 16.99% and 26.24% of lipids from SBP and VOP, respectively. Linoleic, linolenic, oleic, palmitic and palmitoleic acids were major in SBP oil, while VOP oil was composed of almost equal amounts of linoleic and oleic acids. Therefore, remarkably higher diversity of triacylglycerols was identified in SBP. The content of β-sitosterol and α-tocopherol was 359.5-514.5 and 65.38-118.6 mg/100 g, respectively. Hydrocarbons were other quantitatively important lipophilic components, including health beneficial squalene. All extracts improved oxidative stability of mayonnaise. The extracts of berry processing by-products by green extraction method contain valuable bioactive constituents and could be of high interest for applications in functional foods and nutraceuticals.

Lipid Compositions and Geographical Discrimination of 94 Geographically Authentic Wheat Samples Based on UPLC-MS with Non-Targeted Lipidomic Approach

Wheat is the staple food for the world’s major populations. However, chemical characters of geographically authentic wheat samples, especially for the lipids, have not been deeply studied. The present research aimed to investigate lipid compositions of Chinese wheat samples and clarify the major markers that contribute to the geographical differences. A total of 94 wheat samples from eight main wheat-producing provinces in China were evaluated to differentiate their lipid compositions. Based on the data collected from ultra-high-performance-liquid-chromatography tandem time-of-flight mass spectrometry (UPLC-Q/TOF MS), an optimized non-targeted lipidomic method was utilized for analyses. As the results, 62 lipid compounds, including fatty acids, phospholipids, galactolipids, triglycerides, diglycerides, alkylresorcinol, and ceramide were tentatively identified. Partial least squares discriminant analysis (PLS-DA) demonstrated a more satisfying performance in distinguishing wheat samples from different origins compared with principal component analysis (PCA). Further, the abundances of triglycerides and glycerophospholipids with more unsaturated fatty acids were found greater in wheat samples from northern origins of China, while more glycolipids and unsaturated fatty acids arose in southern original wheat samples. These findings describe the lipid profiles of wheat samples in China and could contribute to the quality and safety control for the wheat flour products.

Assessing the Quality of Milk Using a Multicomponent Analytical Platform MicroNIR/Chemometric

In this work, an innovative screening platform based on MicroNIR and chemometrics is proposed for the on-site and contactless monitoring of the quality of milk using simultaneous multicomponent analysis. The novelty of this completely automated tool consists of a miniaturized NIR spectrometer operating in a wireless mode that allows samples to be processed in a rapid and accurate way and to obtain in a single click a comprehensive characterization of the chemical composition of milk. To optimize the platform, milk specimens with different origins and compositions were considered and prediction models were developed by chemometric analysis of the NIR spectra using Partial Least Square regression algorithms. Once calibrated, the platform was used to predict samples acquired in the market and validation was performed by comparing results of the novel platform with those obtained from the chromatographic analysis. Results demonstrated the ability of the platform to differentiate milk as a function of the distribution of fatty acids, providing a rapid and non-destructive method to assess the quality of milk and to avoid food adulteration.

Simple, Rapid Lipidomic Analysis of Triacylglycerols in Bovine Milk by Infusion-Electrospray Mass Spectrometry

Bovine milk is a complex mixture of lipids, proteins, carbohydrates, and other factors of which lipids comprise 3-5% of the total mass. Rapid analysis and characterization of the triacylglycerols (TAG) that comprise about 95% of the total lipid is daunting given the numerous TAG species. In the attached methods paper, we demonstrate an improved method for identifying and quantifying TAG species by infusion-based "shotgun" lipidomics. Because of the broad range of TAG species in milk, a single internal standard was insufficient for the analysis and required sectioning the spectrum into three portions based upon mass range to provide accurate quantitation of TAG species. Isobaric phospholipid interferences were removed using a simple dispersive solid-phase extraction step. Using this method, > 100 TAG species were quantitated by acyl carbon number and desaturation level in a sample of commercially purchased bovine milk.

Determination of mono- and diacylglycerols from E 471 food emulsifiers in aerosol whipping cream by high-performance thin-layer chromatography-fluorescence detection

Mono- and diacylglycerol (MAG and DAG) emulsifiers (E 471) are widely applied to regulate techno-functional properties in different food categories, for example, in dairy products. A method for the determination of MAG and DAG in aerosol whipping cream by high-performance thin-layer chromatography with fluorescence detection (HPTLC-FLD) after derivatization with primuline was developed. For sample preparation, aerosol whipping cream was mixed with ethanol, followed by the addition of water and liquid-liquid extraction with tert-butyl methyl ether. The sample extracts were analyzed by HPTLC-FLD on silica gel LiChrospher plates with n-pentane/n-hexane/diethyl ether (22.5:22.5:55, v/v/v) as mobile phase, when interfering matrix like cholesterol and triacylglycerols were successfully separated from the E 471 food additives. For quantitation, an emulsifier with known composition was used as calibration standard and the fluorescent MAG and DAG were scanned at 366/> 400 nm. Limits of detection and quantitation of 4 and 11 mg/100 g aerosol whipping cream were obtained for both monostearin and 1,2-distearin, respectively, and allowed the reliable quantitation of MAG and DAG from E 471 far below commonly applied emulsifier amounts. Recoveries from model aerosol whipping cream with 400 mg E 471/100 g were determined in a calibration range of 200-600 mg E 471/100 g sample and ranged between 86 and 105% with relative standard deviations below 7%. In aerosol whipping creams from the German market, E 471 amounts ranged between 384 and 610 mg/100 g.

Structure determination of conjugated linoleic and linolenic acids

Conjugated linoleic and linolenic acids (CLA and CLnA) can be found in dairy, ruminant meat and oilseeds, these types of unsaturated fatty acids consist of various positional and geometrical isomers, and have demonstrated health-promoting potential for human beings. Extensive reviews have reported the physiological effects of CLA, CLnA, while little is known regarding their isomer-specific effects. However, the isomers are difficult to identify, owing to (i) the similar retention time in common chromatographic methods; and (ii) the isomers are highly sensitive to high temperature, pH changes, and oxidation. The uncertainties in molecular structure have hindered investigations on the physiological effects of CLA and CLnA. Therefore, this review presents a summary of the currently available technologies for the structural determination of CLA and CLnA, including the presence confirmation, double bond position determination, and the potential stereo-isomer determination. Special focus has been projected to the novel techniques for structure determination of CLA and CLnA. Some possible future directions are also proposed.

Mass spectrometry-based lipidomics in food science and nutritional health: A comprehensive review

With the advance in science and technology as well as the improvement of living standards, the function of food is no longer just to meet the needs of survival. Food science and its associated nutritional health issues have been increasingly debated. Lipids, as complex metabolites, play a key role both in food and human health. Taking advantages of mass spectrometry (MS) by combining its high sensitivity and accuracy with extensive selective determination of all lipid classes, MS-based lipidomics has been employed to resolve the conundrum of addressing both qualitative and quantitative aspects of high-abundance and low-abundance lipids in complex food matrices. In this review, we systematically summarize current applications of MS-based lipidomics in food field. First, common MS-based lipidomics procedures are described. Second, the applications of MS-based lipidomics in food science, including lipid composition characterization, adulteration, traceability, and other issues, are discussed. Third, the application of MS-based lipidomics for nutritional health covering the influence of food on health and disease is introduced. Finally, future research trends and challenges are proposed. MS-based lipidomics plays an important role in the field of food science, promoting continuous development of food science and integration of food knowledge with other disciplines. New methods of MS-based lipidomics have been developed to improve accuracy and sensitivity of lipid analysis in food samples. These developments offer the possibility to fully characterize lipids in food samples, identify novel functional lipids, and better understand the role of food in promoting healt.

Triacylglycerols and Fatty Acid Compositions of Cucumber, Tomato, Pumpkin, and Carrot Seed Oils by Ultra-Performance Convergence Chromatography Combined with Quadrupole Time-of-Flight Mass Spectrometry

The triacylglycerol (TAG) compositions of cucumber, tomato, pumpkin, and carrot seed oils were analyzed using ultra-performance convergence chromatography (UPC2) combined with quadrupole time-of-flight mass spectrometry (Q-TOF MS). A total of 36, 42, 39, and 27 different TAGs were characterized based on their Q-TOF MS accurate molecular weight and MS2 fragment ion profiles in the cucumber, tomato, pumpkin, and carrot seed oils, respectively. Generally, different vegetable seed oils had different TAGs compositions. Among the identified fatty acids, linoleic acid was the most abundant fatty acid in cucumber, tomato, and pumpkin seed oils and the second most abundant in carrot seed oil with relative concentrations of 54.48, 48.69, 45.10, and 15.92 g/100 g total fatty acids, respectively. Oleic acid has the highest concentration in carrot seed oil and the second highest in cucumber, tomato, and pumpkin seed oils, with relative concentrations of 78.97, 18.57, 27.16, and 33.39 g/100 g total fatty acids, respectively. The chemical compositions of TAGs and fatty acids could promote understanding about the chemical profiles of certain vegetable seed oils, thus improving the potential ability to select appropriate oils with specific functions and a high nutritional value and then develop functional foods in the future.

Detection of olive oil adulteration with vegetable oils by ultra-performance convergence chromatography-quadrupole time-of-flight mass spectrometry (UPC2-QTOF MS) coupled with multivariate data analysis based on the differences of triacylglycerol compositions

Three different vegetable oils, including soybean, corn, and sunflower oils, were differentiated from olive oil by using ultra-performance convergence chromatography coupled with quadrupole time-of-flight (UPC2-QTOF MS) and multivariate data analysis based on their differences in triacylglycerol compositions. Then, olive oil was adulterated by adding these three vegetable oils in 1%, 0.75%, and 0.5% (v/v), and the adulterated olive oils were differentiated from the pure olive oils using the similar analytical strategies but different data processing approaches. After that, the representative markers in differentiating the adulterations were selected, and a mathematical model was created to detect the olive oil adulteration based on these specific markers. These results indicated that UPC2-QTOF MS coupled with multivariate data analysis is a sensitive and accurate method in detecting olive oil adulteration, even in 0.5% adulteration level (v/v). This method could be applied in olive oil adulteration detection, and potentially beneficial to the oil industry.

Characterization and comparison of lipids in bovine colostrum and mature milk based on UHPLC-QTOF-MS lipidomics

Lipids in bovine milk have several biological activities, with implications for human health and the physical functionality of foods. However, alterations in the lipid profile of bovine milk during lactation are not well-studied. This study aimed to identify differences in lipids between bovine colostrum and mature milk, using a lipidomics approach. Using an advanced mass spectrometry-based quantitative lipidomics approach, 335 lipids assigned to 13 subclasses were characterized in bovine colostrum (BC) and mature milk (BM). In total, 63 significantly differential lipids (SDLs) were identified. Among the 63 SDLs, the levels of 21 lipids were significantly lower in BM than in BC, including 5 glycerophosphatidylethanolamines (PEs), 1 glycerophosphatidylglycerol (PG), and 15 triacylglycerols (TGs). The levels of the remaining 42 lipids increased in BM, including 1 cardiolipin (CL), 9 diacylglycerols (DGs), 9 dihexosylceramides (Hex2Cers), 3 hexosylceramides (HexCers), 3 glycerophosphatidic acids (PAs), 2 glycerophosphatidylcholines (PCs), 12 PEs, and 3 TGs. Furthermore, the correlations and related metabolic pathways of these 63 SDLs were analyzed to explore the mechanisms that alter bovine milk lipids during lactation. The seven most relevant pathways identified herein, ranked in accordance with their degree of influence on lactation, were glycerophospholipid metabolism, sphingolipid metabolism, glycerolipid metabolism, glycosylphosphatidylinositol-anchor biosynthesis, linoleic acid metabolism, alpha-linolenic acid metabolism, and arachidonic acid metabolism. Our results provide essential insights into mechanisms underlying alterations in bovine milk lipids during different lactation periods, along with practical information of specific nutrition and quality assessments for the dairy industry.

Effects of Fish Oil and Grape Seed Extract Combination on Hepatic Endogenous Antioxidants and Bioactive Lipids in Diet-Induced Early Stages of Insulin Resistance in Rats

Diacylglycerols (DAG) and ceramides have been suggested as early predictors of insulin resistance. This study was aimed to examine the combined effects of fish oil (FO) and grape seed extract (GSE) on hepatic endogenous antioxidants, DAG and ceramides in diet-induced early stages of insulin resistance. Thirty-five rats were fed one of the following diets: (1) a standard diet (STD group), (2) a high-fat high-sucrose diet (HFHS group), (3) an HFHS diet enriched with FO (FO group), (4) an HFHS diet enriched with GSE (GSE group) or (5) an HFHS diet enriched with FO and GSE (FO + GSE group). In the liver, endogenous antioxidants were measured using spectrophotometric and fluorometric techniques, and non-targeted lipidomics was conducted for the assessment of DAG and ceramides. After 24 weeks, the FO + GSE group showed increased glutathione peroxidase activity, as well as monounsaturated fatty acid and polyunsaturated fatty acid-containing DAG, and long-chain fatty acid-containing ceramides abundances compared to the STD group. The FO and GSE combination induced similar activation of the antioxidant system and bioactive lipid accumulation in the liver than the HFHS diet without supplementation. In addition, the FO and GSE combination increased the abundances of polyunsaturated fatty acid-containing DAG in the liver.

Comparative Analysis of the Chemical Consistency Between the Traditional and Mixed Decoction of Maimendong Decoction by Ultra-Performance Liquid Chromatography Coupled to Quadrupole with Time-of-Flight Mass Spectrometry (UPLC-QTOF-MS)-Based Chemical Profiling Approach

Take Maimendong Decoction (MMDD), one of the Chinese classic herbal formulas, as an object to evaluate the chemical consistency between traditional decoction and mixed decoction. The ultra-performance liquid chromatography coupled to quadrupole with time-of-flight mass spectrometry-based chemical profiling approach has been utilized. A total of 48 major peaks are detected from these two decoctions under the present chromatographic and mass spectrometry conditions. The results of negative ion mode show nine significant inconsistencies. Liquiritin, ginsenoside Ro and ginsenoside Rg5/Rk1 are detected with higher intensity in traditional preparation sample than the mixed decoction, while licoisoflavone A is higher in mixed decoction samples than the traditional one. The mechanisms involved in the chemical changes were assumed to be anti-inflammation, anti-oxidative stress and so on, suggesting these two different preparation approaches of MMDD may lead to a possibility of discrepant clinical outcomes.

Comprehensive Characterization of Bovine Milk Lipids: Triglycerides

A comprehensive survey on triglycerides (TAGs) of bovine milk was conducted by a combination of exhaustive liquid chromatography (LC) separation, high-resolution mass spectrometry (MS) detection, and automated lipid molecular feature extraction. A total of 220 groups (a series of species having the same chemical formula and mass) and 3454 molecular species of TAGs were identified based on the accurate mass of the parent ion as well as MS2 information. Sixty-five different fatty acids (FAs) were found across these TAG species; C4:0, C6:0, C8:0, C10:0, C12:0, C14:0, C16:0, C18:0, and C18:1 were the most frequent FAs, whereas C11:3, C11:4, C27:0, C27:1, C28:0, and C28:1 were rare FAs in TAG molecules. The number of species identified represents only a small portion of total TAG molecules that can be theoretically synthesized from 65 FAs. Each TAG group contains on average 15-16 isomeric species (species with different FA composition), but positional isomers do not seem to be widespread. As the isomeric species cannot be completely resolved chromatographically, quantification of TAG was conducted at the group level. The most abundant TAG groups in bovine milk include TAG 34:0, TAG 36:0, TAG 38:1, TAG 38:0, and TAG 40:1. This study provides the most comprehensive milk TAG inventory so far that can be used as a reference for studying milk lipids.

Recent developments on rapid detection of main constituents in milk: a review

Milk is a good source of quality fats, proteins, carbohydrates, minerals, and vitamins. Determining milk constituents is very important in dairy production and is usually conducted by means of physical or chemical processes in laboratories. These methods are time-consuming and cannot satisfy the need in practice. Developing simple, quick, cost-effective, reliable, and sensitive methods on the detection of main constituents in milk is useful for dairy farmers, manufacturers and consumers. In last decades, many rapid detection techniques such as chromatography, spectroscopy, dielectric properties, and sensors, have emerged and shown great potential in the detection of main constituents in liquid milk. In this review, the rapid detection techniques applied to determine the main constituents in milk have been reviewed. Meanwhile, the potential advantages and limitations of these techniques and recommendations for future research have also been proposed.

Quantitative lipidomics reveals alterations in donkey milk lipids according to lactation

The composition of donkey milk is similar to that of human milk. However, the lipid content in donkey milk is lower than that in human milk. Thus far, the lipid composition of donkey milk during lactation has not been well-studied. Through mass spectroscopy-based quantitative lipidomics, we analyzed lipids in donkey colostrum (DC) and mature milk (DM). Thirteen subclasses of 335 lipids were identified in both DC and DM; 60 lipids - 17 upregulated and 43 downregulated - were differentially regulated between DM and DC (Variable Importance in Projection >1, P < 0.05), demonstrating that lipid composition changed with lactation. These different lipids were involved in 19 metabolic pathways, of which glycerophospholipid, linoleic acid, alpha-linolenic acid, glycosylphosphatidylinositol-anchor, glycerolipid, and arachidonic acid metabolism were the most relevant. Our results provide insights into quantitative alterations in donkey milk lipids during lactation, development of donkey milk products, and screening of potential biomarkers.

In-depth lipidomic analysis of tri-, di-, and mono-acylglycerols released from milk fat after in vitro digestion

Milk fat is arguably one of the most complex fats found in nature and varies widely between animal species. Analysis of its digestion products is tremendously challenging, due to the complexity, diversity, and large range of concentrations of triacylglycerols (TAGs) and their digestion products (i.e. diacylglycerols (DAGs), monoacylglycerols (MAGs), and free fatty acids (FFAs)). Therefore, a method combined the solid phase extraction (SPE), high-performance liquid chromatography (HPLC) and multi-dimension mass spectrometry (MDMS) was developed to identify and semi-quantify the TAGs, DAGs and MAGs in milk fat after in vitro digestion. Up to 105, 64, 14 and 30 species of TAGs, DAGs, MAGs, and FFAs were determined with their concentrations of 0.01-22.3, 0.01-39.2, 0.01-47.8, and 0.04-191.0 mg/g fat, respectively, during the in vitro digestion of cow and sheep milk. The validation of the method shows that this method was precise and reliable.

Triglyceride, fatty acid profile and antioxidant characteristics of low melting point fractions of Buffalo Milk fat

BACKGROUND

Among the dietary lipids, milk fat is most complicated as it contains more than one hundred types of fatty acids and several triglycerides. Huge versatility in triglyceride and fatty composition makes it possible to convert milk fat into various fractions on the basis of melting characteristics. Functional properties of milk fat can be increased by converting it into different fractions. After cow milk, buffalo milk is the second largest source of milk and chemical characteristics of buffalo milk fat has been studied in a limited fashion. The main mandate was determination of triglyceride, fatty acid profile and antioxidant characteristics of low melting point fractions of buffalo milk fat for increased industrial applications.

METHODS

Buffalo milk fat (cream) was fractionated at three different temperatures i.e. 25, 15 and 10 °C by dry fractionation technique and packaged in 250 ml amber glass bottles and stored at ambient temperature for 90 days. The fraction of milk fat harvested at 25, 15 and 10 °C were declared as LMPF-25, LMPF-15 and LMPF-10. Unmodified milk fat was used as control (PBMF). Low melting point fractions were analyzed for triglyceride composition, fatty acid profile, total phenolic contents, DPPH free radicals scavenging activity, reducing power, free fatty acids, peroxide value, iodine value and conjugated dienes at 0, 45 and 90 days of storage.

RESULTS

In LMPF-10, concentrations of C₃₆, C₃₈, C₄₀, and C₄₂ were 2.58, 3.68, 6.49 and 3.85% lower than PBMF. In LMPF-25, concentrations of C₄₄, C₄₆, C₄₈, C₅₀, C₅₂ and C₅₄ were 0.71, 1.15, 2.53, 4.8, 0.39 and 2.39% higher than PBMF. In LMPF-15, concentrations of C₄₄, C₄₆, C₄₈, C₅₀, C₅₂ and C₅₄ were 2.45, 4.2, 3.47, 5.92, 2.38 and 3.16% higher than PBMF. In LMPF-10, concentrations of C₄₄, C₄₆, C₄₈, C₅₀, C₅₂ and C₅₄ were 2.8, 5.6, 5.37, 7.81, 3.81 and 4.45% higher than PBMF. LMPF-25, LMPF-15 and LMPF-10 had higher concentration of unsaturated fatty acids as compared PBMF. Total phenolic contents of buffalo milk fat and its fractions were in the order of LMPF-10 > LMPF-15, LMPF-25 > PBMF. Storage period of 45 days had a non-significant effect on total flavonoid content. 2, 2-Diphenyl-1-picrylhydrazyl free radical scavenging activity (DPPH) free radical scavenging activity of LMP-25, LMPF-15 and LMPF-10 were 4.8, 13.11 and 25.79% higher than PBMF. Reducing power of PBMF, LMPF-25, LMPF-15 and LMPF-10 were 22.81, 28.47, 37.51 and 48.14, respectively. Estimation of free fatty acids after the 90 days of storage duration, no significant difference was found in content of free fatty acids in unmodified milk fat and low melting point fractions. Testing of peroxide value in 90 days old samples showed that peroxide value of PBMF, LMPF-25, LMPF-15 and LMPF-10 was 0.54, 0.98, 1.46 and 2.22 (MeqO₂/kg), respectively. Storage period up to 45 days had a non-significant effect on anisidine value, iodine value and conjugated dienes.

CONCLUSION

Low melting point fractions of buffalo milk fat had higher concentration of unsaturated fatty acids and more antioxidant capacity than unmodified milk fat with reasonable storage stability.

Assessment of Repeatability in Supercritical Fluid Chromatography with Electrochemical Detection Based on the ISO 11843 Part 7

The present study proposes a method for the assessment of repeatability in supercritical fluid chromatography with electrochemical detection (SFC-ECD), based on the ISO 11843 part 7 (ISO 11843-7:2018) which can theoretically provide detection limits and standard deviation (S.D.) through the stochastic properties of baseline noise without repetitive measurements of real samples. On the baseline noise of SFC-ECD, large-amplitude and periodic noises with less than 0.05 Hz were observed, and the power spectrum of the baseline noise showed 1/f fluctuation (f = frequency). It was found that the present power spectrum analysis, according to the law of error propagation, can provide suitable noise parameters to calculate S.D. of baseline noise and a relative S.D. (RSD) of peak area by ISO 11843-7. The chromatographic determinations of α-, β-, γ- and δ-tocopherol have been taken as examples. In the present SFC-ECD, the RSDs of peak areas for α-, β-, γ- and δ-tocopherol obtained by ISO 11843-7 were within 95% confidence intervals of the RSD of them obtained by repetitive measurements (n = 6). Thus, we found that ISO 11843-7 is applicable to the assessment of repeatability in SFC-ECD for determining tocopherols without repetitive measurements.

Rapid and direct determination of fatty acids and glycerides profiles in Schisandra chinensis oil by using UPLC-Q/TOF-MSE

Fatty acids and glycerides are globally accepted quality and nutrition indicators of oils. Schisandra chinensis (S. chinensis) is a good functional oil source, with an oil content of 10-50% (dry weight). In this study, the UPLC-Q/TOF-MS^E technique was developed to profile FFA and glycerides in the S. chinensis oils directly. The results showed that all of the 36 FFA calibration equations of the mixture standard had good linear relationships (R² > 0.99). The limit of detection for the tested compounds ranged from 0.0001 to 0.0200 μg/mL, while the limit of quantification ranged from 0.0005 to 0.1300 μg/mL. In total, seventeen FFAs, six diglycerides and 20 triglycerides were identified. Linoleic, oleic, stearic and palmitic acids were the most abundant FFAs in the S. chinensis oils. It was also found that S. chinensis oil is rich in the L-L, L-L-L, O-L-L and O-L-O glycerides. These results will be helpful for the use of this technique in physicochemical evaluation and for further application development.

Toxicokinetics and Metabolism of 3-Monochloropropane 1,2-Diol Dipalmitate in Sprague Dawley Rats

Fatty acid esters of 3-monochloropropane 1,2-diol (3-MCPD) are a group of processing-induced toxicants. To better clarify their possible toxicological effects and mechanisms, it is important to investigate their absorption, distribution, metabolism, and excretion. In this study, the kinetic parameters of 3-MCPD dipalmitate in Sprague Dawley (SD) rat plasma were determined using ultraperformance liquid chromatography-triple quadrupole mass spectrometry. 3-MCPD dipalmitate was absorbed in rats with a C_max of 135.00 ng/mL, a T_1/2 of 3.87 h, a T_max of 2.5 h, an MRT of 5.08 h, a CL of 3.50 L/h/g, a V_d of 21.34 L/g, and an AUC_0-∞ of 458.47 h·ng/mL. A total of 17 metabolites were identified, and 16 of them were reported for the first time. Furthermore, these metabolites were examined for their presences in the liver, kidney, testis, brain, spleen, thymus, intestine, plasma, feces, and urine samples 2, 6, 12, 24, and 48 h after oral administration of 3-MCPD dipalmitate using Metabolynx software.