Lipidomics profiling of goat milk, soymilk and bovine milk by UPLC-Q-Exactive Orbitrap Mass Spectrometry

Critical overview of mass spectrometry-based lipidomics approach for evaluating lipid oxidation in foods

Mass spectrometry-based lipidomics, developed through rapid advancements in instruments and techniques, provides comprehensive analyses of individual lipidomes in diverse biological systems. This contribution summarizes the limitations of classical methods for measuring lipid oxidation in foods and presents current novel technologies for evaluating lipid oxidation. Notably, this study introduces the mass spectrometry-based lipidomics approach and its utility in assessing lipid oxidation through various analytical modes, supported by numerous examples. This overview offers significant insights into the use of mass spectrometry-based lipidomics for measuring lipid oxidation in foods, proposing lipidomics analysis as a promising method to address the limitations of classical approaches.

1H-NMR Lipidomics, Comparing Fatty Acids and Lipids in Cow, Goat, Almond, Cashew, Soy, and Coconut Milk Using NMR and Mass Spectrometry

Background/Objectives: Lipids are an important component of human nutrition. Conventional milk is obtained from animals, and dairy milk is consumed by many people worldwide. Recently, milk consumers have been increasingly shifting towards plant-based milk options. The aim of the study was the qualitative identification of lipid metabolites in animal- and plant-based milk, the identification and comparison of the fatty acids (FAs) of milk, and the qualitative identification of the lipid groups among the milk varieties. Methods: Milk samples were obtained from local grocery stores. Lipids were extracted using a modified Folch method and analyzed using nuclear magnetic resonance (NMR) metabolomics. Gas and liquid chromatography mass spectrometry methods (GC-MS and LC-MS) were used to identify the FAs and lipid groups. Lipid weights were compared and the NMR profiles of the lipids analyzed by multivariate statistical analysis. Principal component analysis was performed for the milk lipids obtained from the animal, and plant milk varieties. Results: Clustering of NMR data showed two main clusters: cow/almond/cashew and goat/soy/coconut. GC-MS analysis of the methylated fatty acids (FAs) showed the presence of 12:0, 14:0, 16:0, 16:1, 17:0, 18:0, 18:1, 18:2, 20:1, and 20:2 in all milk types, while FAs 19:0 and 20:4 were observed only in the dairy milk. LC-MS data showed common masses that may indicate the presence of mono- and diacyl glycerols and several lysophospholipids among the different types of milk. Conclusions: This study shows the advantage of using NMR, GC-MS, and LC-MS to differentiate the lipids among different milk types and compare them on one platform.

Lipidomics of coconut, almond and soybean milks - Detailed analysis of polar lipids and comparison with bovine milk

In this work, the lipidomic analysis on polar components of almond, coconut, and soy beverages was performed by liquid chromatography quadrupole time-of-flight mass spectrometry. A comparison with bovine milk was also performed. A total of 30 subclasses of polar lipids, belonging mainly to glycerophospholipids and sphingolipids, and a total of 572 molecular species were identified. Coconut showed various kinds of sphingolipids, belonging to hexosylceramides and sulfatides. Soy is particularly rich in molecular species of phospholipids. Fatty acids with chain length from 16 to 18 were the most common in almond. Numerous species of sphingomyelins were found in bovine milk, differently from plant-based beverages. Furthermore, a principal component analysis based on the polar lipid data was applied to discriminate samples, with 21 molecular species identified as biomarkers. This research opens interesting perspectives on vegetable beverages as bovine milk alternatives, especially in vegetarian and vegan diets.

Effects of interactions between microorganisms and lipids on inferior volatile compound production during cold storage of grouper (Epinephelus coioides)

The interaction between microorganisms, proteins, and lipids plays a critical role in the odor production of fish. To explore the specific impact of the interaction between lipids and microorganisms on the overall odor of grouper, this study excluded the influence of proteins and assessed lipid (POV and TBARS) and microbial characteristics (biofilm mass and ATP content) in lipid solutions. The Results showed that microbial growth and lipid oxidation mutually promote each other. Lipidomics analysis identified 44 differential lipids, and microbial diversity analysis pinpointed five key microorganisms (Carnobacterium, Pseudomonas, Gluconacetobacter, Vagococcus, and Shewanella). Furthermore, 20 key volatile compounds (VOCs) related to odor changes in the grouper lipid solution were identified using HS-SPME-GC-MS. Correlation network analysis revealed potential microbial and lipid contributions to VOC categories, including alcohols, aldehydes, ketones, and nitrogen- and sulfur-containing compounds. This study provides new insights into the roles of microorganisms and lipids in flavor formation, offering valuable knowledge for improving seafood quality control.

Variations in the milk lipidomic profile of lactating dairy cows fed the diets containing alfalfa hay versus alfalfa silage

Alfalfa is primarily stored as silage or hay in livestock production. Previous research has shown that the storage method of grass significantly influences milk composition. This study aimed to investigate milk production performance and lipid composition in dairy cows fed diets consisting of alfalfa hay or alfalfa silage as roughage. Forty-two mid-lactation Holstein dairy cows were selected and randomly divided into three groups, each receiving a total mixed ration consisting of alfalfa hay (AH), 50% alfalfa silage + 50% alfalfa hay (AHAS), or alfalfa silage (AS). The results showed that milk fat content (P = 0.049) and milk fat yield (P < 0.001) were significantly higher in the AH and AHAS groups compared to the AH group. With increased supplementation of alfalfa silage in the diet, ω-3 polyunsaturated fatty acid content increased significantly (P < 0.001), while ω-6 polyunsaturated fatty acid content (P = 0.007) and the ratio of ω-6 to ω-3 polyunsaturated fatty acids decreased (P < 0.001). The contents of sphingomyelins, phosphatidylserines, phosphatidylethanolamines, and phosphatidylglycerols in the AHAS and AS samples were higher than in the AH samples, although the differences were not statistically significant. Additionally, the content of phosphatidylcholines was significantly higher in the AS group compared to the AH group (P = 0.032). In conclusion, feeding dairy cows a diet consisting of alfalfa silage can increase the major phospholipid content and polyunsaturated fatty acid composition in raw milk, which is more conducive to human health. These findings provide valuable insights into the benefits of alfalfa silage for dairy cows.

Characterization of phospholipidome in milk, yogurt and cream, and phospholipid differences related to various dairy processing methods

Milk phospholipids have multiple health benefits, but the deficiency of detailed phospholipid profiles in dairy products brings obstacles to intake calculation and function evaluation of dairy phospholipids. In present study, 306 phospholipid molecular species were identified and quantified among 207 milk, yogurt and cream products using a HILIC-ESI-Q-TOF MS and a HILIC-ESI-QQQ MS. The phospholipid profiles of five mammals' milk show that camel milk contains the most abundant phosphatidylethanolamine, phosphatidylserine and sphingomyelin; cow, yak and goat milk have similar phospholipidomes, while buffalo milk contains abundant phosphatidylinositol. Fewer plasmalogens but more lyso-glycerolphospholipids were found in ultra-high-temperature (UHT) sterilized milk than in pasteurized milk, and higher proportions of lyso-glycerolphospholipid/total phospholipid were observed in both cream and skimmed/semi-skimmed milk than whole milk, indicating that UHT and skimming processes improve glycerolphospholipid degradation and phospholipid nutrition loss. Meanwhile, more diacyl-glycerolphospholipids and less of their degradation products make yogurt a better phospholipid resource than whole milk.

Comprehensive lipidomics study of basa catfish and sole fish using ultra-performance liquid chromatography Q-extractive orbitrap mass spectrometry for fish authenticity

The authenticity of fish products has become a widespread issue in markets due to substitution and false labeling. Lipidomics combined with chemometrics enables the fraudulence identification of food through the analysis of a large amount of data. This study utilized ultra-high-performance liquid chromatography (UHPLC)-QE Orbitrap MS technology to comprehensively analyze the lipidomics of commercially available basa catfish and sole fish. In positive and negative ion modes, a total of 779 lipid molecules from 21 lipid subclasses were detected, with phospholipid molecules being the most abundant, followed by glycerides molecules. Significant differences in the lipidome fingerprinting between the two fish species were observed. A total of 165 lipid molecules were screened out as discriminative features to distinguish between basa catfish and sole fish, such as TAG(16:0/16:0/18:1), PC(14:0/22:3), and TAG(16:1/18:1/18:1), etc. This study could provide valuable insights into authenticating aquatic products through comprehensive lipidomics analysis, contributing to quality control and consumer protection in the food industry.

Omega-3 Long-Chain Polyunsaturated Fatty Acids in Nonseafood and Estimated Intake in the USA: Quantitative Analysis by Covalent Adduct Chemical Ionization Mass Spectrometry

Omega-3 long-chain polyunsaturated fatty acids (LCPUFA) play critical roles in human development and health. Their intake is often effectively estimated solely based on seafood consumption, though the high intake of terrestrial animal-based foods with minor amounts of LCPUFA may be significant. Covalent adduct chemical ionization (CACI) tandem mass spectrometry is one approach for de novo structural and quantitative analysis of minor unsaturated fatty acids (FA), for which standards are unavailable. Here, CACI-MS and MS/MS are used to identify and quantify minor omega-3 LCPUFA of terrestrial animal foods based on the application of measured response factors (RFs) to various FA. American mean intakes of pork, beef, chicken, and eggs contribute 20, 27, 45, and 71 mg/day of docosahexaenoic acid (DHA), respectively. The estimated intake of omega-3 DHA, eicosapentaenoic acid, and docosapentaenoic acid from nonseafood sources is significant, at 164, 103, and 330 mg/day, greater than most existing estimates of omega-3 LCPUFA intake.

Machine learning-guided REIMS pattern recognition of non-dairy cream, milk fat cream and whipping cream for fraudulence identification

The illegal adulteration of non-dairy cream in milk fat cream during the manufacturing process of baked goods has significantly hindered the robust growth of the dairy industry. In this study, a method based on rapid evaporative ionization mass spectrometry (REIMS) lipidomics pattern recognition integrated with machine learning algorithms was established. A total of 26 ions with importance were picked using multivariate statistical analysis as salient contributing features to distinguish between milk fat cream and non-dairy cream. Furthermore, employing discriminant analysis, decision trees, support vector machines, and neural network classifiers, machine learning models were utilized to classify non-dairy cream, milk fat cream, and minute quantities of non-dairy cream adulterated in milk fat cream. These approaches were enhanced through hyperparameter optimization and feature engineering, yielding accuracy rates at 98.4-99.6%. This artificial intelligent method of machine learning-guided REIMS pattern recognition can accurately identify adulteration of whipped cream and might help combat food fraud.

Lipidomic insights into the reaction of baking lipases in cakes

Lipases are promising improvers of cake batter and baking properties. Their suitability for use in various cake formulations cannot be predicted yet, because the reactions that lead to macroscopic effects need to be unravelled. Therefore, the lipidome of three different cake recipes with and without lipase treatment was assessed by ultra high performance liquid chromatography-mass spectrometry before and after baking. By comparing the reaction patterns of seven different lipases in the recipes with known effects on texture, we show that lipase substrate specificity impacts baking quality. Key reactions for the recipes were identified with the help of principal component analysis. In the eggless basic cake, glyceroglycolipids are causal for baking improvement. In pound cake, lysoglycerophospholipids were linked to textural effects. Lipase substrate specificity was shown to be dependent on the recipe. Further research is needed to understand how recipes can be adjusted to achieve optimal lipase substrate specificity for desirable batter and baking properties.

Determination of adulteration, geographical origins, and species of food by mass spectrometry

Food adulteration, mislabeling, and fraud, are rising global issues. Therefore, a number of precise and reliable analytical instruments and approaches have been proposed to ensure the authenticity and accurate labeling of food and food products by confirming that the constituents of foodstuffs are of the kind and quality claimed by the seller and manufacturer. Traditional techniques (e.g., genomics-based methods) are still in use; however, emerging approaches like mass spectrometry (MS)-based technologies are being actively developed to supplement or supersede current methods for authentication of a variety of food commodities and products. This review provides a critical assessment of recent advances in food authentication, including MS-based metabolomics, proteomics and other approaches.

Lipidomics of coconut, almond and soybean milks - Comprehensive characterization of triacylglycerol class and comparison with bovine milk

Nowadays, plant-based milk consumption, as part of a healthy diet, is continuously increasing. In this paper, for the first time a lipidomic analysis on molecular species of triacylglycerol (TG) fraction of plant-based beverages (almond, soy, coconut) was performed by liquid chromatography quadrupole time-of-flight mass spectrometry. A total of 557 TG molecular species was measured, showing significantly different profiles between milk alternatives, compared with bovine milk. The most abundant TG molecular species were TG 18:1_18:1_18:1 and 18:1_18:1_18:2 for almond, TG 18:2_18:2_18:2 and 16:0_18:2_18:2 for soy, TG 12:0_10:0_12:0 and 12:0_12:0_14:0 for coconut. Unconventional fatty acids were detected in almond and soy. The main TG with ethereal linkage were TG-O 56:2, TG-O 56:4, and TG-O 56:5, while the main oxygenated TG was TG 54:5;1O. A total of 30 molecular species were identified as biomarkers for milk differentiation by principal component analysis, providing an interesting support for milk authentication and detection of adulteration on a larger sampling.

A Critical Overview of HPLC-MS-Based Lipidomics in Determining Triacylglycerol and Phospholipid in Foods

With the current advancement in mass spectrometry (MS)-based lipidomics, the knowledge of lipidomes and their diverse roles has greatly increased, enabling a deeper understanding of the action of bioactive lipid molecules in plant- and animal-based foods. This review provides in-depth information on the practical use of MS techniques in lipidomics, including lipid extraction, adduct formation, MS analysis, data processing, statistical analysis, and bioinformatics. Moreover, this contribution demonstrates the effectiveness of MS-based lipidomics for identifying and quantifying diverse lipid species, especially triacylglycerols and phospholipids, in foods. Further, it summarizes the wide applications of MS-based lipidomics in food science, such as for assessing food processing methods, detecting food adulteration, and measuring lipid oxidation in foods. Thus, MS-based lipidomics may be a useful method for identifying the action of individual lipid species in foods.

Spectrophotometric- and LC/MS-Based Lipidomics Analyses Revealed Changes in Lipid Profiles of Pike Eel (Muraenesox cinereus) Treated with Stable Chlorine Dioxides and Vacuum-Packed during Chilled Storage

Spectrophotometric- and liquid chromatography/mass spectrometry (LC/MS)-based lipidomics analyses were performed to explore the changes of lipid profiles in pike eel (Muraenesox cinereus) under stable chlorine dioxides (ClO₂) and vacuum-packed treatment during chilled storage. The peroxide value (PV) and malondialdehyde (MDA) content in ClO₂ treated and vacuum-packaged (VP) samples were significantly reduced compared to simple-packaged (SP) samples during whole chilled storage. The LC/MS-based lipidomics analyses identified 2182 lipid species in the pike eel muscle classified into 39 subclasses, including 712 triglycerides (TGs), 310 phosphatidylcholines (PCs), 153 phosphatidylethanolamines (PEs), and 147 diglycerides (DGs), among others. Further, in comparison with fresh pike eel (FE) muscle, 354 and 164 higher and 420 and 193 lower abundant levels of differentially abundant lipids (DALs) were identified in SP samples and VP samples, respectively. Compared with the VP batch, 396 higher and 404 lower abundant levels of DALs were identified in the SP batch. Among these, PCs, PEs, TGs, and DGs were more easily oxidized/hydrolyzed, which could be used as biomarkers to distinguish FE, SP, and VP samples. This research provides a reference for controlling lipid oxidation in fatty fish.

An Updated Review of Soy-Derived Beverages: Nutrition, Processing, and Bioactivity

The global market for plant-based drinks is experiencing rapid growth driven by consumer demand for more sustainable diets, including vegetarian and vegan options. Soy beverages in particular are gaining popularity among individuals with lactose intolerance and milk protein allergies. They are considered an excellent source of high-quality protein, vitamin B, unsaturated fatty acids, and beneficial phytochemicals such as phytosterols, soy lecithins, and isoflavones. This review presents a comprehensive market survey of fifty-two soy beverages available in Spain and other European countries. The predominant category among those evaluated was calcium and vitamin-fortified drinks, accounting for 60% of the market. This reflects the need to address the nutritional gap compared to cow's milk and meet essential dietary requirements. The review covers the technological aspects of industrial soy milk production, including both traditional methods and innovative processing techniques. Additionally, it analyzes multiple studies and meta-analyses, presenting compelling evidence for the positive effects of soy beverages on various aspects of health. The review specifically examines the contributions of different components found in soy beverages, such as isoflavones, proteins, fiber, and oligosaccharides. Moreover, it explores controversial aspects of soy consumption, including its potential implications for growth, puberty, fertility, feminization, and the thyroid gland.

Lipidomics of Sannen goat milk subjected to pasteurization and spray drying based on LC-ESI-MS/MS

The purpose of this study was to evaluate the effects of pasteurization and spray drying on goat milk lipids by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and multiple variable statistics. A total of 1061 lipids assigned to 29 subclasses in raw and thermal-treated groups were identified. One hundred and 85 different lipids (DLs) (VIP ≥ 1 and |Log₂FC| ≥ 1.0) were selected from pairwise comparisons of goat milk by different treatments. Glycerophospholipids were the most affected subclasses by thermal processes, especially by spray drying. Five potential lipid markers [(DG (16:1_18:0), TG (18:1_22:1_18:2), Cer (t17:2/31:0), LPC (0:0/20:0), and LPS (20:0/0:0] were used to distinguish different treated goat milk. Moreover, glycerophospholipid metabolism was the primary pathway of DLs. These results would provide more details of lipid profiles in thermally treated (pasteurization and spray drying) goat milk.

Progress of Mass Spectrometry-Based Lipidomics in the Dairy Field

Lipids play important biological roles, such as providing essential fatty acids and signaling. The wide variety and structural diversity of lipids, and the limited technical means to study them, have seriously hampered the resolution of the mechanisms of action of lipids. With advances in mass spectrometry (MS) and bioinformatic technologies, large amounts of lipids have been detected and analyzed quickly using MS-based lipidomic techniques. Milk lipids, as complex structural metabolites, play a crucial role in human health. In this review, the lipidomic techniques and their applications to dairy products, including compositional analysis, quality identification, authenticity identification, and origin identification, are discussed, with the aim of providing technical support for the development of dairy products.

The Study of Yak Colostrum Nutritional Content Based on Foodomics

The utilization of yak milk is still in a primary stage, and the nutrition composition of yak colostrum is not systematically characterized at present. In this study, the lipids, fatty acids, amino acids and their derivatives, metabolites in yak colostrum, and mature milk were detected by the non-targeted lipidomics based on (ultra high performance liquid chromatography tandem quadrupole mass spectrometer) UHPLC-MS, the targeted metabolome based on gas chromatography-mass spectrometer (GC-MS), the targeted metabolome analysis based on UHPLC-MS, and the non-targeted metabolome based on ultra high performance liquid chromatography tandem quadrupole time of flight mass spectrometer (UHPLC-TOF-MS), respectively. Meanwhile, the nutrition composition of yak colostrum was compared with the data of cow mature milk in the literatures. The results showed that the nutritive value of yak colostrum was higher by contrast with yak and cow mature milk from the perspective of the fatty acid composition and the content of Σpolyunsaturated fatty acids (PUFAs), Σn-3PUFAs; the content of essential amino acid (EAA) and the ratio of EAA/total amino acid (TAA) in yak colostrum were higher than the value in yak mature milk; and the content of functional active lipids including phosphatidylcholines (PC), phosphatidylglycerol (PG), phosphatidylserine (PS), lyso-phosphatidylcholine (LPC), lyso-phosphatidylglycerol (LPG), lyso-phosphatidylinositol (LPI), sphingomyelin (SM), ganglioside M3 (GM3), ganglioside T3 (GT3), and hexaglycosylceramide (Hex1Cer) in yak colostrum, was higher than the value of yak mature milk. Moreover, the differences of nutritive value between yak colostrum and mature milk were generated by the fat, amino acids and carbohydrate metabolism that were regulated by the ovarian hormone and referencesrenin-angiotensin-aldosterone system in yaks. These research results can provide a theoretical basis for the commercial product development of yak colostrum.

Effect of homogenization on lipid profiling in Saanen goat milk based on UHPLC-QTOF-MS lipidomics

Homogenization might change the lipid composition of goat milk. This study aimed to investigate the lipid profiles, and identify different lipids (DLs) of raw goat milk (RGM) and homogenized goat milk (HGM) using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and multivariate statistics. Fifty-six DLs (VIP ≥ 1 and |Log₂FC| ≥ 1.0) were identified from 1057 lipids assigned to 29 subclasses in RGM and HGM. Notably, there were many phosphatidylcholines (PCs) decreased after homogenization, while lysophosphatidylcholines (LPCs) were opposite. Our results provide more details on the impact of homogenization on goat milk lipids.

Comparative analysis of lipid components in fresh Crassostrea Hongkongensis (raw) and its dried products by using high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (HPLC/Q-TOF-MS)

The lipids of the oyster (Crassostrea hongkongensis) have a special physiological activity function, which is essential to maintain human health. However, comprehensive research on their lipids species and metabolism is not so common. In our study, based on the high-performance liquid chromatography/quadrupole time-of-flight mass spectrometer (HPLC/Q-TOF-MS), the non-targeted lipidomics research of Crassostrea hongkongensis fresh and dried products was determined. Meanwhile, we analyzed its lipid outline, screened the differences between the lipid molecules of Crassostrea hongkongensis fresh and dried products, and determined the lipid metabolic pathway. Results showed that 1,523 lipid molecules were detected, in which polyunsaturated fatty acids mostly existed in such lipids as phosphoglyceride. Through the multivariate statistical analysis, according to the conditions of P &lt; 0.05, FC &gt; 2 or FC &lt; 0.05, and VIP &gt; 1.2, 239 different lipid molecules were selected, including 37 fatty acids (FA), 60 glycerol phospholipids (GP), 20 glycerin (GL), 38 sheath lipids (SP), 31 steroid lipids (ST), 36 polyethylene (PK), and 17 progesterone lipids (PR). Combined with the Kyoto Encyclopedia of Genes and Genomes (KEGG), the differential lipid molecules were analyzed to mainly determine the role of the glycerin phospholipid metabolic pathway. As a whole, the results of this study provide the theoretical basis for the high-value utilization of oysters and are helpful to the development of oysters' physiological activity functions and deep utilization.

Accurate quantification of TAGs to identify adulteration of edible oils by ultra-high performance liquid chromatography-quadrupole-time of flight-tandem mass spectrometry

Edible oils play important roles in biological functions, and triacylglycerols (TAGs) in edible oils are complex mixtures. This makes accurate TAGs quantitation quite difficult that bring economically motivated food adulteration. Herein, we demonstrated a strategy for accurate quantification of TAGs in edible oils, which could be applied in identification of olive oil adulteration. The results showed that the proposed strategy could significantly improve the accuracy of TAG content determination, reduce the relative error of fatty acids (FAs) content determination, and present a wider accurate quantitative range than that of gas chromatography-flame ionization detection. Most important, this strategy coupled with principal component analysis could be used to identify adulteration of high-priced olive oil with cheaper soybean oils, rapeseed oils or camellia oils at a lower concentration of 2%. These findings indicated that the proposed strategy could be regarded as a potential method for edible oils quality and authenticity analysis.

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.

Lipid Profiles of Human Milk and Infant Formulas: A Comparative Lipidomics Study

Infant formulas (IFs) are prevalent alternatives for human milk (HM), although their comparative lipid profiles have not been fully investigated. We adopted lipidomics to analyze and compare in-depth the lipid patterns of HM and IFs. The results indicated that the distribution of fatty acids (FAs) and the structure of triacylglycerols varied substantially in the analyzed samples. A total number of 425 species were identified during the analysis. HM was abundant in triacylglycerols that contained unsaturated and long-chain FAs (>C13), while triacylglycerols in IFs were mainly comprised of saturated and medium-chain FAs (C8-C13). Higher levels of sphingomyelin were observed in HM. Furthermore, HM and IF1 contained 67 significantly differential lipids (SDLs), and 73 were identified between HM and IF2. These SDLs were closely associated with nine metabolic pathways, of which the most significant was the glycerophospholipid metabolism. The results shed light on the differences between the lipid profiles of human and infant formula milks, and provide support for designing Chinese infant formula.

Quantification of phospholipids and glycerides in human milk using ultra-performance liquid chromatography with quadrupole-time-of-flight mass spectrometry

Human milk lipids, which are an important source of energy and affect growth and development of infants, require a comprehensive method for its qualitative and quantitative analysis. This work describes a method for the analysis of phospholipids, glycerides, free fatty acids and gangliosides in human milk by ultra-performance liquid chromatography using a C18 column with quadrupole-time-of-flight mass spectrometry (Q-TOF-MS). The lipids were extracted by liquid-liquid extraction and phospholipids were separated by solid phase extraction (SPE). The chromatographic columns with two different specifications (4.6 mm × 150 mm, and 3 mm × 50 mm) were used to detect phospholipids and glycerides in human milk, respectively. The sphingolipids and glycerides were analyzed in positive ion mode, and the glycerophospholipids and free fatty acids were analyzed in negative ion mode. Both internal and external standards were used for absolute quantification in this experiment. 483 species of lipids, including phospholipids, glycerides, free fatty acids and gangliosides, in human milk were analyzed using UPLC-Q-TOF-MS with high sensitivity and good linearity, with coefficient of correlation above 0.99, the relative standard deviation of accuracy and precision less than 10%. The results in a large number of human milk samples showed that this method was suitable for qualitative and quantitative analysis of lipids in human milk, even for other mammalian milk and infant formulae.

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.

Effect of Lipids in Yak Muscle under Different Feeding Systems on Meat Quality Based on Untargeted Lipidomics

Simple Summary

With the development of living standards, consumers are paying more and more attention to meat quality and flavor. When consumers choose meat, they directly pay attention to meat quality and flavor, so the meat quality and flavor directly decide meat price and sales volume. Better meat quality and flavor are the crucial factors that increase the additional value of meat. Because of its special nutritional value and taste, yak meat is popular with consumers. The intramuscular lipids can greatly affect the meat quality and flavor, but there is no report on the effect of lipids in yak muscle on the meat quality and flavor. In this study, we studied the characterization of lipids in yak muscle under different feeding systems and further explored the key lipids affecting yak meat quality and flavor. This study can provide new insight into the improvement of yak meat quality and flavor.

Abstract

The effect of lipids on yak meat quality and volatile flavor compounds in yak meat under graze feeding (GF) and stall feeding (SF) was explored using untargeted lipidomics based on liquid chromatography–mass spectrometry (LC-MS) in this study. First, the volatile flavor compounds in longissimus dorsi (LD) of SF and GF yaks were detected by gas chromatography–mass spectrometry (GC-MS). In total 49 and 39 volatile flavor substances were detected in the LD of GF and SF yaks, respectively. The contents of pelargonic aldehyde, 3-hydroxy-2-butanone and 1-octen-3-ol in the LD of both GF and SF yaks were the highest among all detected volatile flavor compounds, and the leading volatile flavor substances in yak LD were aldehydes, alcohols and ketones. In total, 596 lipids were simultaneously identified in the LD of SF and GF yaks, and the leading lipids in the LD of both GF and SF yaks were sphingolipids (SPs), glycerolipids (GLs) and glycerophospholipids (GPs). Seventy-five significantly different lipids (SDLs) between GF and SF yaks were identified in the LD. The high content of TG(16:1/18:1/18:1), TG(16:0/17:1/18:1) and TG(16:0/16:1/18:1), PE(18:0/22:4) and PC(18:2/18:0) can improve the a* (redness) and tenderness of yak muscle. The changes in volatile flavor compounds in yak muscle were mainly caused by TG(18:1/18:1/18:2), TG(18:0/18:1/18:1), TG(16:0/17:1/18:1), TG(16:0/16:1/18:1), PC(18:2/18:0), TG(16:1/18:1/18:1), PI(18:0/20:4), TG(16:1/16:1-/18:1) and TG(17:0/18:1/18:1). The above results provide a theoretical basis for improving yak meat quality from the perspective of intramuscular lipids.

Comparative Lipidomics Analysis of Human and Ruminant Milk Reveals Variation in Composition and Structural Characteristics

In the present study, the different lipidomes between human milk and ruminant milk were compared. The 471, 376, 467, and 87 differential lipids were identified in human versus cow, goat, sheep, and camel groups, respectively. According to multivariate statistical analysis, lipids in human and camel milk were closer but differed from other milk. The distributions of long-chain and polyunsaturated fatty acids of triglycerides (TGs), the proportions of functional TGs (OPO, OPL, and PPO), and many kinds of phospholipids (PLs) (PS, PI, GD, GM3, and Cer) in human milk were similar to those in camel milk. The similar structure of TGs and proportion of PLs in human milk to camel milk might contribute to their similar digestion and bioactivity properties. Camel milk could be considered as a new resource of lipid base for infant formula. Minor PLs should also be considered for designing formula. Our results provide a new sight for humanized lipids in infant formula.

Analysis and comparison of lipids in Saanen goat milk from different geographic regions in China based on UHPLC-QTOF-MS lipidomics

The lipids in goat milk from Guangdong Province (GGM), Shaanxi Province (SGM), and Inner Mongolia Province (NGM) were analyzed and compared using untargeted lipidomics. A total of 16 lipid sub-classes and 638 lipid molecules were identified in the three groups. The main lipids were diacylglycerol (DG), triacylglycerol (TG), and glycerophosphatidylethanolamine (PE). The contents of glycerophosphatidylcholine (PC), PE, glycerophosphatidylinositol (PI), sphingomyelin (SM), glucosylceramide (GlcCer), lactosylceramide (LacCer), DG, and TG were significantly different (P < 0.05) in three groups. Moreover, 173 significantly different lipids were screened out, and 13 lipid molecules could be applied as potential lipid markers for identifying the geographic region of goat milk. In addition, the related metabolic pathways were also analyzed. A hypothetical scheme was drawn by linking the most relevant metabolic pathways. This work will provide basics for the establishment of the Saanen goat milk traceability system and provide comprehensive lipid information for the goat milk of different regions.

Optimizing accelerated solvent extraction combined with liquid chromatography-Orbitrap mass spectrometry for efficient lipid profile characterization of mozzarella cheese

In this study, a novel Accelerated Solvent Extraction (ASE) procedure combined with UHPLC-Q-Orbitrap-MS was developed for detailed untargeted lipid profile of mozzarella cheese. Response Surface Methodology and Pareto front, using a Central Composite Design (CCD), were employed to define the optimised combination of extraction temperature, number of extraction cycles and mix of solvents. LipidSearch™ software was used for a reliable and accurate lipid identification. A total of 13 subclasses, including ceramides, diacylglycerols, triacylglycerols, lysophosphatidylcholines, lysophosphatidylethanolamines, phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, sphingomyelins, bismethyl phosphatidic acids, cholesterol ester, zymosterol ester, hexosyl ceramides were measured. The elaboration of the CCD showed that the solvents ratio was the main factor affecting the extraction efficiency. The optimised ASE method, together with the Folch extraction, synergistically contributed to a complete characterization of lipid profile of mozzarella cheese, confirming ASE technique, associated with high resolution mass spectrometry detection, as an efficient tool for Lipidomics in food science.

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.

Optimized Identification of Triacylglycerols in Milk by HPLC-HRMS

This work has developed an optimized workflow for the targeted analysis of triacylglycerols (TAGs) in milk by liquid chromatography coupled with a Q-Exactive Orbitrap mass spectrometer. First, the effects of resolution (17,500; 35,000; 70,000; 140,000) and automatic gain control target (AGC, from 2×104, 2×105, 1×106, and 3×106) have been optimized with the goal to minimize the injection time, maximize the number of scans, and minimize the mass error. Then, the flow rate of the liquid chromatography system was also optimized by maximizing the number of theoretical plates. The resulting optimized parameters consisted of a flow rate of 200 μL/min, mass resolution of 35,000, and AGC target of 2×105. Such optimal conditions were applied for targeted TAG analysis of milk fat extracts. Up to 14 target triglycerides in milk fat were identified performing a data-dependent HPLC-HRMS-MS2 experiment (t-SIM-ddMS2). The findings reported here can be helpful for MS-based lipidomic workflows and targeted milk lipid analysis.

Effects of dietary phosphatidylcholine and sphingomyelin on DSS-induced colitis by regulating metabolism and gut microbiota in mice

Patients with inflammatory bowel diseases tend to show alteration of lipid profiles. It remains unknown whether dietary intake with specific lipids, such as phosphatidylcholine (PC) and sphingomyelin (SM), have distinguishable effects against IBD. Here, a preclinical study using dextran sulphate sodium (DSS)-induced colitis mice model was applied to explore/compare the effects by PC and SM. Results showed that PC treatment (p.o., 30 mg/kg b.w., 15 days) exerted higher inhibitory activity than the same dosage of SM supplementation on colonic tissue lesions and pro-inflammatory cytokines expressions induced by DSS. Integrative analysis of the metabolome and microbiome indicated that PC and SM supplementation could modulate endogenous tryptophan metabolism, arginine and proline metabolism, purine metabolism, bile secretion, as well as vitamin digestion and absorption, closely correlated with their regulation on the abundance of Lactobacillus, Faecalibacterium, Dubosiella, Turicibacter, and Parasutterella communities in the gut. Based on these data, PC is a more promising candidate for preventing colitis than SM. Our findings provided a scientific foundation for further clinical research to screen more efficient dietary intervention strategy for colitis prevention.

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.

Lipidomic profiling reveals molecular modification of lipids in hepatopancreas of juvenile mud crab (Scylla paramamosain) fed with different dietary DHA/EPA ratios

Untargeted lipidomic analysis was conducted to explore how different dietary docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) ratio and, specifically, how an optimal ratio (2.3) compared to a suboptimum ratio (0.6) impacted lipid molecular species and the positional distribution of fatty acids in hepatopancreas of mud crab. The results indicated that major category of lipid affected by dietary DHA/EPA ratio was glycerophospholipids (GPs). The optimum dietary DHA/EPA ratio increased the contents of DHA bound to the sn-2 and sn-3 positions of phosphatidylcholine (PC) and triacylglycerol, EPA bound to the sn-2 position of phosphatidylcholine and 18:2n-6 bound to the sn-2 position of phosphatidylethanolamine (PE). Increased dietary DHA/EPA ratio also led to competition between arachidonic acid (ARA) and 18:2n-6 bound to esterified sites. Appropriate dietary DHA/EPA ratio can not only improve the growth performance and nutritional quality of mud crab, but also provide higher quality products for human consumers.

A Comprehensive Review of Lipidomics and Its Application to Assess Food Obtained from Farm Animals

Lipids are one of the major macronutrients essential for adequate growth and maintenance of human health. Their structure is not only complex but also diverse, which makes systematic and holistic analyses challenging; consequently, little is known regarding the relationship between phenotype and mechanism of action. In recent years, rapid advancements have been made in the fields of lipidomics and bioinformatics. In comparison with traditional approaches, mass spectrometry-based lipidomics can rapidly identify as well as quantify >1,000 lipid species at the same time, facilitating comprehensive, robust analyses of lipids in tissues, cells, and body fluids. Accordingly, lipidomics is now being widely applied in various fields, particularly food and nutrition science. In this review, we discuss lipid classification, extraction techniques, and detection and analysis using lipidomics. We also cover how lipidomics is being used to assess food obtained from livestock and poultry. The information included herein should serve as a reference to determine how to characterize lipids in animal food samples, enhancing our understanding of the application of lipidomics in the field in animal husbandry.

Development of a high-throughput method for the comprehensive lipid analysis in milk using ultra-high performance supercritical fluid chromatography combined with quadrupole time-of-flight mass spectrometry

Milk lipids are one of the most complex materials in nature and are associated with many physiological functions, hence it is important to comprehensively characterize lipids profiles to evaluate the nutritional value of milk. A quick method was developed by ultra-high performance supercritical fluid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry (UHPSFC-ESI-QTOF-MS) to analyze the non-polar and polar lipids profiles of cow, goat, buffalo, human milk, and infant formulas in 7 min. All chromatographic conditions were carefully optimized and their effect on the chromatographic behavior of lipid classes and species was discussed. Under optimized conditions, 12 lipid classes (triacylglycerols, diacylglycerols, monoglyceride, fatty acids, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylglycerol, sphingomyelin, lyso-phosphatidylcholine, and lyso-phosphatidylethanolamine) were separated and each class was further separated in single analysis to facilitate the identification. 250 lipid species in real samples were characterized and quantified. This result demonstrates the applicability of the UHPSFC-ESI-QTOF-MS method in the high-throughput and comprehensive lipid analysis of milk, and will hopefully help to provide nutritionists with the lipid distribution in different types of milk, as well as help in the design of more suitable infant formula for babies.