An overview of food lipids toward food lipidomics

Improving lipidomic coverage for animal matrices by optimizing extraction methods and resuspension solvents based on UHPLC-Q-Exactive Orbitrap MS/MS

Due to the complexity of animal matrices and the different polarities of lipids, the measurement methods are expected to cover a comprehensive range of lipid species. Three extraction methods (chloroform/methanol, methyl tert-butyl ether, and Soxhlet methods) and three resuspension solvents (methanol, isopropanol/acetonitrile = 1:1, and isopropanol/acetonitrile = 9:1) were used to compare the lipid species, contents, and ionization efficiency of Spanish mackerel and duck muscles. Overall, the chloroform/methanol extraction method was the most effective in capturing a diverse array of lipid species. The redissolution solvent isopropanol/acetonitrile (1,1) was highly efficient for detecting triglycerides, while methanol was effective in detecting diacylglycerols and phospholipids. Optimizing the measurement conditions of lipids with different polarities provides a valuable reference for lipid extraction and structural elucidation in different muscle tissues. Furthermore, it supports the determination of differential markers for animal lipid metabolism studies or food authentication using an untargeted lipidomic approach.

Recent advances in lipid analysis by capillary electromigration methods, 2019-2024

Following a long period during which Capillary Electrophoresis (CE) was little used for lipid analysis (see Poinsot et al., Electrophoresis, 40, 2019, 190-211), the last five years have seen an increase in publications on this subject. Micellar Electrokinetic Chromatography (MEKC) can now compete with Gas Chromatography (GC) for the analysis of fatty acids, while non-aqueous capillary electrophoresis (NACE) now allows the study of fatty acids as well as phospholipids or glycolipids. As NACE also allows easy coupling to Mass Spectrometry (MS) in both positive and negative Electrospray Ionization (ESI), the technique has now become sufficiently robust, and for laboratories equipped with GC or Liquid Chromatography (LC) to consider using CE, particularly as it presents the advantage of much faster sample preparation than with GC for fatty acids and a resolution identical to LC for phospholipids and glycolipids. In this article, we will therefore describe the advances made in this area over the last five years.

Microwave-mediated formation of lotus-seed starch-palmitic acid complexes and their multi-scale structural changes

Recent studies have revealed that starch-lipid complexation can significantly impact gut health via the formation of V-type resistant starch. This study used varying microwave (MW) power levels (600, 700, 800, 900, 1000 W) to prepare V-type lotus-seed starch (LS)-palmitic acid (PA) complexes and investigates their multi-scale structural and thermal properties. The results indicate that MWs promote hydrophobic LS-PA complexation to form a B + V6II-type crystalline structure, with the V-type complexation rate found to positively correlate with MW power. Specifically, a higher MW power is more conducive to guiding the evolution of the disordered structure in the complex system back to the ordered arrangement and enhancing the crystallinity and stability of the system. The evolution of this V-type crystallization process peaks at an MW power of 1000 W MW to afford a complexing index of 55.409 %. Further thermal-property analyses reveal that the V-type complexed starch is mainly arranged as highly thermally stable accumulated single-helix structures that dissociate at 100-105 °C. These findings provide valuable data for regulating V-type complex formation through MW treatment and establish a theoretical foundation for precisely designing healthy starch-based foods.

Integrating widely targeted and oxylipin-targeted lipidomics unravels lipid characteristic evolution and oxidation markers in walnuts during deterioration

The susceptibility of walnut lipids to deterioration constitutes challenges for industry development, and the oxylipins formed during this process remain to be explored. This study employed lipidomics to reveal the dynamic evolution of lipid characteristics and identify oxidation markers from oxylipins in walnuts during accelerated storage. Glycerophospholipid (GP) content continuously declined in the initial and severe deterioration stages. The accumulation of diglycerides and partial lysophospholipids characterized initial deterioration. Triglycerides were prone to direct oxidation, while GPs tended to be first hydrolyzed. GP metabolism especially phosphatidylethanolamine degradation triggered walnut deterioration. Moreover, ten oxylipins derived from linoleic acids were identified in walnuts. Trans-EKODE-(E)-Ib, 13-HODE, 9-HODE, and 9(S),12(S),13(S)-TriHOME were screened as oxidation markers. The cellular structure exhibited the cell membrane and oil body membrane rupture during deterioration. Potential mechanisms of lipid deterioration were proposed, providing a scientific basis and guidance in optimizing quality control strategies and assessing practical deterioration degrees of walnuts.

The properties of Pickering emulsions stabilized by bacterial cellulose nanofibrils and its retarding effect on lipid digestion

The rate of lipid digestion can be delayed by the interface modulation of O/W Pickering emulsions. In this study, bacterial cellulose nanofibrils prepared by ball milling synergized with electron beam irradiation (B-IB50) were used as stabilizers to prepare Pickering emulsions. Results showed that B-IB50 formed emulsion systems with good stability. Especially when the content of B-IB50 was >0.6 wt%, emulsions showed excellent storage and environmental stability. Notably, at pH 2.0, the electrostatic repulsion between fibrils was weakened leading to closer cross-linking and giving better protection to the oil droplets. When the content of B-IB50 in emulsions increased from 0.2 wt% to 1.0 wt%, the release of FFA decreased from 66.7 % to 37.8 % during digestion, which indicated that the presence of more B-IB50 inhibited the digestion of lipids. Main mechanisms were proposed for the results: (1) B-IB50 formed a dense interface layer that reduced the binding area of bile salts and lipases; (2) B-IB50 formed the three-dimensional network structure limiting the displacement of bile salts and lipases, thereby reducing the binding to lipids. This study provided theoretical ideas for developing emulsion-based functional foods with lipid-reducing effects.

Comprehensive quantitative profiling of vegetable oil oxidation products by NMR-based oxylipidomics

Lipid oxidation is one the major causes of food deterioration. Current advancement in mechanistic understanding is limited by the lack of high-throughput methods that can simultaneously quantify a wide range of oxidation product classes, such as lipid hydroperoxides, epoxides, ketones, hydroxides, and aldehydes. Here, we introduce an NMR-based 'oxylipidomics' platform by providing the annotation of 42 substructures formed during lipid oxidation in vegetable oils. The annotated substructures accounted for respectively 93, 90 and 70% of the oxidation products of triolein, trilinolein, and trilinolenin. The spectral assignments allowed for quantification of lipid oxidation products in vegetable oil at class (e.g., epoxides) and substructure level (e.g., trans-epoxides) at the commonly available field strength of 14.1 T (600 MHz). We anticipate that our workflow will enable rapid assessment of health risks, unravelling of precursor-sensory relationships, rational design of antioxidant strategies, and in-depth mechanistic studies into food lipid oxidation.

Effects of Hot Air, Vacuum, and Conductive Drying on the Fatty Acid Profile of Cucurbita maxima Pulp and Its Processing By-Products

Considering the short shelf life of fresh pumpkin due to its high water content and the extensive use of dried pumpkin in the food industry, it is necessary to find an efficient drying method that minimizes water activity and preserves nutritional properties. In this study, the effects of hot air drying (HAD), vacuum drying (VAD), and conductive drying (CD) at 50, 60, and 70 °C on fatty acid profiles were investigated to determine optimal drying conditions that preserve fatty acid (FA) quality and associated nutritional benefits. Results showed that drying methods had a significant effect (p < 0.05) on fatty acid composition and yield, resulting in different amounts of palmitic, oleic, linoleic, and linolenic acids as major FAs compared to fresh pulp. The saturated FA content was higher in CD pulp (up to 42.37%), followed by HAD and VAD. Oleic acid, as the most important representative of monounsaturated FAs, came from VAD (up to 30.64%). Linoleic and linolenic acid, as the most important polyunsaturated FAs of the omega-6 and omega-3 fatty acids, were found in higher proportions in CD pulp at 50 and 60 °C (up to 31.12%) and HAD pulp at 60 and 70 °C with an airflow velocity of 1.5 m/s (up to 39.70%). In addition, the peel and seeds, the by-products resulting from the processing of the fruit pulp, were also evaluated with regard to the fatty acid profile. Two fractions also contained the four major FAs in representative amounts, indicating their valuable reuse.

Foodomics as a Tool for Evaluating Food Authenticity and Safety from Field to Table: A Review

The globalization of the food industry chain and the increasing complexity of the food supply chain present significant challenges for food authenticity and raw material processing. Food authenticity identification now extends beyond mere adulteration recognition to include quality evaluation, label compliance, traceability determination, and other quality-related aspects. Consequently, the development of high-throughput, accurate, and rapid analytical techniques is essential to meet these diversified needs. Foodomics, an innovative technology emerging from advancements in food science, enables both a qualitative judgment and a quantitative analysis of food authenticity and safety. This review also addresses crucial aspects of fully processing food, such as verifying the origin, processing techniques, label authenticity, and detecting adulterants, by summarizing the omics technologies of proteomics, lipidomics, flavoromics, metabolomics, genomics, and their analytical methodologies, recent developments, and limitations. Additionally, we analyze the advantages and application prospects of multi-omics strategies. This review offers a comprehensive perspective on the food chain, food safety, and food processing from field to table through omics approaches, thereby promoting the stable and sustained development of the food industry.

Comparative lipidomics analysis of seed oils from nine tropical fruits: Emphasizing the fatty acid and lipid molecule profiles

While tropical fruit seeds are considered potential sources of functional or edible vegetable oils, their lipid profiles are poorly documented. Herein, the lipid profiles of nine tropical fruit seed oils were systematically evaluated and compared using lipidomics and chemometrics techniques. Cherimoya exhibited the highest total lipid content, while avocado had the lowest. Canistel, cherimoya, and durian displayed a 9cC18:1 predominance. The remaining six seed oils were dominated by 9c12cC18:2n-6. In total, 1370 lipid molecules were identified, with triacylglycerol being the predominant subclass. Passion fruit, cherimoya, and durian had the highest glycerolipid, sphingolipid, and fatty acyl contents, respectively. Litchi exhibited the highest levels of glycerophospholipid and saccharolipid. Chemometric modeling screened 134 differential lipid molecules as markers for distinguishing between various tropical fruit seed oils. Positive correlations were primarily observed among the differential lipid molecules. Overall, these findings provide valuable insights into the integrated utilization of tropical fruit seed oils.

A comprehensive foodomics analysis of rambutan seed oils: Focusing on the physicochemical parameters, lipid concomitants and lipid profiles

A foodomics approach was employed to systematically characterize and compare the quality parameters, antioxidant activity, minor-components, fatty acid composition, and lipid profiles of the seed oils from the three most popular rambutan varieties in China. The total lipid content ranged from 23.40 to 25.77 g/100 g. The fatty acids 9cC18:1 (39.84%-40.92%) and C20:0 (28.45%-30.23%) were identified as the dominant ones, which are uncommon among higher plants. All oil samples exhibited low AI and TI values. BR-7 exhibited the highest levels of squalene (21.48 mg/kg), cholesterol (144.43 mg/kg), and tocopherol (17.42 mg/kg), and the lowest levels of polyphenols (24.21 mg GAE/kg). Additionally, a total of 807 lipid species were identified, with TAG, DGTS, and PE being the predominant ones. Multivariate statistical analyses revealed significant variations in lipid profiles among the varieties, particularly in glycerophospholipids and sphingolipids. Fifty-seven distinct lipids were identified as potential markers for distinguishing between rambutan varieties. Furthermore, a hypothetical scenario was developed by linking relevant lipid metabolism pathways. These findings establish a theoretical framework for comprehending rambutan seed oil in depth and unlocking its high-value potential.

Comprehensive insights into the mechanism of flavor formation driven via inoculation with mixed starter cultures in dry-fermented tilapia sausages: Integration of macrogenomics, volatilomics, and lipidomics

To investigate the mechanisms of flavor formation in dry-fermented tilapia sausages, the volatiles, bacterial community, and lipid composition during fermentation were analyzed using gas chromatography-ion mobility spectrometry, 16S high throughput sequencing, and ultra-performance liquid chromatography-mass spectrometer. Pediococcus pentosaceus, Staphylococcus xylosus, and Staphylococcus carnosus became dominant bacteria during the fermentation. A total of 66 volatiles and 293 lipids (48 differential lipids) were identified. PC and PE content decreased. Aldehyde and 1-octen-3-ol content decreased. Most esters and ketones content increased during fermentation. Six metabolic pathways associated with differential lipids were identified by enrichment analysis. Glycerophospholipid metabolism was the main metabolic pathway. Correlation analysis revealed that PC and PE were precursors for volatiles, including PC 16:0/18:2 and PE 18:0/22:6. The dominant bacteria facilitate the hydrolysis of PC and PE, leading to the formation of esters and ketones. This study provides a theoretical basis for the targeted regulation of fermented sausage flavors.

Nutraceutical potential of Mediterranean agri-food waste and wild plants: Green extraction and bioactive characterization

The agricultural waste and wild plants of the Mediterranean region offer significant nutraceutical potential, rich in bioactive compounds such as phenolics, carotenoids, lipids and volatile organic compounds. These compounds exhibit health-promoting properties, including antioxidant, neuroprotective and anti-inflammatory effects. Advanced analytical techniques such as HPLC, GC-MS and NMR are essential for the accurate chemical characterization of these bioactives. Green extraction methods, including ultrasound-assisted, enzyme-assisted and cold plasma-assisted extractions, provide efficient and environmentally friendly alternatives to classical techniques for the isolation of bioactive compounds. The valorization of Mediterranean agricultural by-products, such as olive pomace, grape seeds, and citrus peels, exemplifies sustainable approaches to the utilization of these underutilized resources. This chapter explores the bioactive characterization and green extraction methods that contribute to unlocking the nutraceutical potential of Mediterranean plant waste and wild plants, highlighting their role in the development of functional foods and natural health products.

Sex-Specific Lipid Profiles and Flavor Volatiles in Giant Salamander (Andrias davidianus) Tails Revealed by Lipidomics and GC-IMS

To elucidate the relationships between lipid components and odor traits, this study comparatively characterized the distinct lipid compositions and flavor volatiles in giant salamander tails of different sexes via mass-spectrometry-based lipidomics and GC-IMS. A total of 3145 fat metabolites were detected in male and female giant salamander tails, with the largest contributors being triglycerides (TGs, 840) and phosphatidylcholines (PCs, 383). Notably, the contents of PCs and TGs were greater in female tails than in male tails, and the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were also greater in the female group. Additionally, a total of 45 volatile components were detected, namely, 14 aldehydes, 14 alcohols, 9 ketones, 3 acids, 3 esters, 1 ether, and 1 amine. Alcohols (29.96% to 34.85%) and aldehydes (21.07% to 22.75%) were the predominant volatiles. Multivariate statistical analysis revealed 22 key differential fats and 26 differential odor substances as distinguishing labels between sexes. Correlation analysis revealed that the concentrations of triethylamine, dimethyl sulfide, ethanol-D, and 3-methyl butanal-D were significantly positively correlated with the concentrations of diglyceride (DG) (26:6e), cardiolipin (CL) (59:4), acylcarnitine (AcCa) (22:4), and triglyceride (TG) (52:10) (p < 0.01). Threefold cross-validation revealed that the prediction accuracies of these differential lipids and volatile compounds for sex recognition via the random forest model were 100%. These findings might not only provide insight into the effects of sexes on the lipid and volatile profiles of giant salamander tails but also provide clues for their gender recognition.

Exploring oxylipins in processed foods: Understanding mechanisms, analytical perspectives, and enhancing quality with lipidomics

Oxylipins are active lipid compounds formed through the oxidation of unsaturated fatty acids. These compounds have drawn considerable attention due to the potential impact on human health and processed food quality. Therefore, this study aimed to deepen current understanding and assess recent analytical advancements regarding the physiological roles of oxylipins in processed food products using lipidomics. The mechanisms behind oxylipins production in processed foods were extensively investigated, underscoring potential associations with chronic diseases. This indicates the need for innovative strategies to mitigate harmful oxylipins levels to enhance the safety and shelf life of processed food products. The results showed that mitigation methods, including the use of antioxidants and optimization of processing parameters, reduced oxylipins levels. The integration of lipidomics with food safety and quality control processes is evident in cutting-edge methods such as nuclear magnetic resonance and mass spectrometry for compliance and real-time evaluation. Aside from envisioning the future trajectory of food science and industry through prospective studies on oxylipins and processed foods, the results also provide the basis for future investigations, innovation, and advancements in the dynamic field of food science and technology.

Dissecting new lipids and their composition in herbal tea using untargeted LC/MS

Herbal teas and beverages have gained global attention because they are rich in natural bioactive compounds, which are known to have diverse biological effects, including antioxidant and anticarcinogenic properties. However, the lipidomic profiles of herbal teas remain unclear. In this study, we applied an untargeted lipidomics approach using high-performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry to comprehensively profile, compare, and identify unknown lipids in four herbal teas: dokudami, kumazasa, sugina, and yomogi. A total of 341 molecular species from five major classes of lipids were identified. Multivariate principal component analysis revealed distinct lipid compositions for each of the herbs. The fatty acid α-linolenic acid (FA 18:3) was found to be abundant in kumazasa, whereas arachidonic acid (FA 20:4) was the most abundant in sugina. Interestingly, novel lipids were discovered for the first time in plants; specifically, short-chain fatty acid esters of hydroxy fatty acids (SFAHFAs) with 4-hydroxy phenyl nonanoic acid as the structural core. This study provides insight into the lipidomic diversity and potential bioactive lipid components of herbal teas, offering a foundation for further research into their health-promoting properties and biological significance.

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.

From Oxidized Fatty Acids to Dimeric Species: In Vivo Relevance, Generation and Methods of Analysis

The occurrence of free fatty acids (FFAs) and the generation of reactive oxygen species (ROS) such as hydroxyl radicals (HO●) or hypochlorous acid (HOCl) is characteristic of inflammatory diseases, for instance, rheumatoid arthritis. Unsaturated fatty acids react with ROS yielding a variety of important products such as peroxides and chlorohydrins as primary and chain-shortened compounds (e.g., aldehydes and carboxylic acids) as secondary products. These modified fatty acids are either released from phospholipids by phospholipases or oxidatively modified subsequent to their release. There is increasing evidence that oligomeric products are also generated upon these processes. Fatty acid esters of hydroxy fatty acids (FAHFAs) are considered as very important products, but chlorinated compounds may be converted into dimeric and (with smaller yields) oligomeric products, as well. Our review is structured as follows: first, the different types of FFA oligomers known so far and the mechanisms of their putative generation are explained. Industrially relevant products as well as compounds generated from the frying of vegetable oils are also discussed. Second, the different opinions on whether dimeric fatty acids are considered as "friends" or "foes" are discussed.

Untargeted Lipidomics Reveal Quality Changes in High-Moisture Japonica Brown Rice at Different Storage Temperatures

Low temperatures are an effective way of delaying grain rancidity and deterioration. However, little is known about the difference in quality changes in high-moisture japonica brown rice at different storage temperatures. In this study, the storage quality changes in japonica brown rice with a 15.50% moisture content stored at 15 °C, 20 °C, and 25 °C were investigated. In addition, an untargeted lipidomics analysis coupled with gas chromatography and mass spectrometry (GC-MS) was applied to analyze the volatile compounds and metabolite changes in the high-moisture japonica brown rice. The results showed that storage at 15 °C could well maintain the color and aroma stability of the brown rice and delay the increase in fatty acid value (FAV). The lipidomics results showed that storage at 15 °C delayed glycerolipid and sphingolipid metabolism and reduced glycerophospholipid catabolism in the brown rice. The low-temperature environment regulated these three metabolic pathways to maintain higher contents of triglycerides (TG), phosphatidylserine (PS), abd phosphatidylethanolamine (PE), and lower contents of diglycerides (DG), OAcyl-(gamma-hydroxy) FA (OAHFA), ceramides (Cer), and glycosylceramides (Hex1Cer) in the high-moisture japonica brown rice, which maintained the storage stability of the brown rice. Our results proposed the cryoprotection mechanism of postharvest brown rice from the perspective of volatile compounds and metabolite changes, providing a foothold for the further exploration of low-temperature storage as a safe and efficient cryoprotectant in the grain storage field.