Lipid Class Composition Research Articles

Lipidomic Profiling of Common Wheat Flours from 1891-2010.

Wheat lipids are a minor constituent of wheat, with an important influence on its processing properties. While breeding aimed to improve the protein composition of wheat flour, its influence on the lipid composition remains unknown. We therefore analyzed the lipidome of 60 different common wheat (Triticum aestivum) flours representing cultivars registered and grown in Germany from 1891 to 2010. Four different extraction techniques were tested before the application of a semiquantitative, untargeted UHPLC-MS/MS method. The measurements included 16 different lipid classes and 102 different lipid species. Based on the lipid profile, discrimination between old (registered between 1891 to 1950) and modern (1951 to 2010) cultivars was possible. While the lipid class composition remained constant, differences were due to variations within the class of triacylglycerols, with modern cultivars containing less unsaturated fatty acids than the older ones. Our results imply that improving the lipid class composition of common wheat is a promising target for further breeding.

Effect of seven baking lipases on the lipid class composition of three different cakes

AbstractLipases are effective clean-label improvers for the baking quality of cake. Insights into lipase activities in different cake formulations in combination with the effect on batter/dough and baking quality are needed to further reveal the underlying mechanisms. Therefore, a method using normal phase high-performance liquid chromatography coupled to an evaporative light scattering detector was adapted and validated for the five most abundant lipid classes in three common cake recipes, namely triacylglycerols, diacylglycerols, monoacylglycerols, glycerophosphocholine and lysoglycerophosphocholine. The method revealed total changes of 0.2 mg/g to 186.5 mg/g in lipid class content per dry weight after lipase treatments. Comparative investigations on batter/dough and products of basic cake, pound cake and brioche without or with addition of seven lipases showed that the substrate specificity of lipases is the decisive factor for their effectiveness regarding improved dough and product quality. A high lipase activity only supported already matching substrate specificities. Graphical abstract

Changes in maternal blood and placental lipidomic profile in obesity and gestational diabetes: Evidence for sexual dimorphism.

Obesity and gestational diabetes (GDM) are associated with adverse pregnancy outcomes and program the offspring for cardiometabolic disease in a sexually dimorphic manner. The placenta transfers lipids to the fetus and uses these substrates to support its own metabolism impacting the amount of substrate available to the growing fetus. We collected maternal plasma and placental villous tissue following elective cesarean section at term from women who were lean (pre-pregnancy BMI 18.5-24.9), obese (BMI>30) and type A2 GDM (matched to obese BMI) with male or female fetus (n=4 each group). Lipids were extracted and fatty acid composition of different lipid classes were analyzed by LC-MS/MS analysis. Significant changes in GDM vs obese, GDM vs lean, and obese vs lean were determined using t-test with a Tukey correction set at p<0.05. In placental samples 436 lipids were identified, among which 85 showed significant changes. Of note only in male placentas significant decreases in C22:6 - docosahexaenoic acid (DHA) in phosphatidylcholine (PC) and triglyceride lipid species were seen when comparing tissue from GDM women to lean. In maternal plasma we observed no effect of obesity. GDM or fetal sex. This is the first study assessing fatty acid composition of lipids in matched maternal plasma and placental tissue from lean, obese, and GDM women stratified by fetal sex. It highlights how GDM affects distribution of fatty acids in lipid classes changes in a sexually dimorphic manner in the placenta.

Extraction of healthy oils from fish viscera by conventional and advanced technologies

Fish viscera is a by-product of fish processing that has limited use as added-value products. The current issue of circular economy to produce recycled and zero waste products, therefore, the utilization of fish viscera for valuable products is important to explore. One of the valuable components of fish viscera is fish oil, which is characterized by being high in polyunsaturated fatty acids (PUFA). The limited exploration of fish viscera for potential utilization requires a comprehensive review of the visceral characteristics of various fish species. This article reviews the nutritional characteristics of various fish viscera, lipid class composition, fish viscera oil characteristics, and various methods of fish viscera oil extraction, both by conventional and advanced technologies. The main contribution of this review is to provide information about fish viscera, their potential as a source of fish oil, and extraction methods which are suitable for various industrial applications and purposes, including health applications for ω-3 fatty acids.

Unwrapping the (glyco-)lipidome in the microalgae Microchloropsis gaditana: Effects of eco-friendly extraction methods

Microalgae have recently captivated worldwide attention because of their extraordinary lipid composition, which includes essential omega-3 and omega-6 long-chain polyunsaturated fatty acids (LC-PUFA), neutral lipids, and more complex lipids (glycolipids and phospholipids), as well as eicosanoids. To explore this further, we present a novel (glyco-)lipidomics strategy, including a green chemistry extraction approach, liquid chromatography high-resolution mass spectrometry (LC-HRMS) lipid profiling, and a comprehensive data evaluation workflow. Using untargeted lipidomics based on LC-HRMS approaches, we studied the lipid composition up to the molecular species level of the microalgae Microchloropsis gaditana (formerly Nannochloropsis gaditana), focusing on the distribution of saturated, monounsaturated, and polyunsaturated fatty acids in different lipid classes. Our analysis successfully identified 520 lipid molecular species from 18 lipid classes. Regarding fatty acid composition, our primary focus was on elucidating the distribution of LC-PUFA across the different microalgal lipid classes. This particular strategy holds potential as it may unravel the use of microalgal lipids as innovative sources of food ingredients. Our findings show that LC-PUFA are relatively elevated in membrane lipids, in which cholesterol esters (ChE) have the highest PUFA share (94 %), followed by polar membrane lipids (glycolipids and phospholipids), with phosphatidylethanolamines (PE) up to 67 %, phosphatidylglycerols (PG) up to 47 %, and monogalactosyldiacylglycerols (MGDG) up to 47 % PUFA content. This highlights the high percentage of PUFA in the structural parts of microalgae and the importance of these lipid classes as a reservoir for PUFA. Finally, we also compared a classical Folch extraction method with environmentally friendly ultrasound-assisted extraction approaches and enzymatic pre-treatments to investigate the lipid composition and enrichment of valuable lipid classes. Thus, this extensive analysis of the (glyco-)lipidome of Microchloropsis gaditana provides valuable insights into the existing knowledge about this microalgae species, enhancing our understanding of the complex lipid composition and opening up new opportunities for potential applications in the biotechnology and food industry.

The Presence of Bioactive Compounds in European Eel (Anguilla anguilla) Skin: A Comparative Study with Edible Tissue.

The presence of bioactive compounds in European eel (Anguilla anguilla) skin was studied. Proximate and lipid class compositions and analysis of the fatty acid (FA) profile (individual FAs; FA groups, i.e., saturated, monounsaturated, and polyunsaturated; FA ratios, i.e., polyunsaturated/saturated, ω3/ω6) were determined and compared to the composition of the eel muscle. As a result, higher (p < 0.05) levels of proteins (271.6 g·kg-1), lipids (38.0 g·kg-1), ash (27.7 g·kg-1), and ω6 FAs were observed in the skin tissue. Contrary, the muscle tissue showed higher (p < 0.05) moisture, ω3 FA, and ω3/ω6 ratio values. Regarding lipid classes, a higher (p < 0.05) proportion of phospholipids (111.1 g·kg-1 lipids), free sterols (104.7 g·kg-1 lipids), α-tocopherol (274.0 mg·kg-1 lipids), and free FAs (43.6 g·kg-1 lipids) was observed in the skin tissue. No differences (p > 0.05) between both tissues could be detected for triacylglycerol and FA group (saturated, monounsaturated, and polyunsaturated) values and for the polyunsaturated/saturated FA ratio. It is concluded that European eel skin, a by-product resulting from commercial processing, can be considered a valuable source for the food and pharmaceutical industries by providing value-added constituents such as proteins, lipids, ω3 FAs, phospholipids, and α-tocopherol.

Plasma Lipidomic Profiling Using Mass Spectrometry for Multiple Sclerosis Diagnosis and Disease Activity Stratification (LipidMS).

This investigation explores the potential of plasma lipidomic signatures for aiding in the diagnosis of Multiple Sclerosis (MS) and evaluating the clinical course and disease activity of diseased patients. Plasma samples from 60 patients with MS (PwMS) were clinically stratified to either a relapsing-remitting (RRMS) or a chronic progressive MS course and 60 age-matched controls were analyzed using state-of-the-art direct infusion quantitative shotgun lipidomics. To account for potential confounders, data were filtered for age and BMI correlations. The statistical analysis employed supervised and unsupervised multivariate data analysis techniques, including a principal component analysis (PCA), a partial least squares discriminant analysis (oPLS-DA) and a random forest (RF). To determine whether the significant absolute differences in the lipid subspecies have a relevant effect on the overall composition of the respective lipid classes, we introduce a class composition visualization (CCV). We identified 670 lipids across 16 classes. PwMS showed a significant increase in diacylglycerols (DAG), with DAG 16:0;0_18:1;0 being proven to be the lipid with the highest predictive ability for MS as determined by RF. The alterations in the phosphatidylethanolamines (PE) were mainly linked to RRMS while the alterations in the ether-bound PEs (PE O-) were found in chronic progressive MS. The amount of CE species was reduced in the CPMS cohort whereas TAG species were reduced in the RRMS patients, both lipid classes being relevant in lipid storage. Combining the above mentioned data analyses, distinct lipidomic signatures were isolated and shown to be correlated with clinical phenotypes. Our study suggests that specific plasma lipid profiles are not merely associated with the diagnosis of MS but instead point toward distinct clinical features in the individual patient paving the way for personalized therapy and an enhanced understanding of MS pathology.

Protein production dynamics and physiological adaptation of recombinant Komagataella phaffii at near-zero growth rates

BackgroundSpecific productivity (qP) in yeast correlates with growth, typically peaking at intermediate or maximum specific growth rates (μ). Understanding the factors limiting productivity at extremely low μ might reveal decoupling strategies, but knowledge of production dynamics and physiology in such conditions is scarce. Retentostats, a type of continuous cultivation, enable the well-controlled transition to near-zero µ through the combined retention of biomass and limited substrate supply. Recombinant Komagataella phaffii (syn Pichia pastoris) secreting a bivalent single domain antibody (VHH) was cultivated in aerobic, glucose-limited retentostats to investigate recombinant protein production dynamics and broaden our understanding of relevant physiological adaptations at near-zero growth conditions.ResultsBy the end of the retentostat cultivation, doubling times of approx. two months were reached, corresponding to µ = 0.00047 h−1. Despite these extremely slow growth rates, the proportion of viable cells remained high, and de novo synthesis and secretion of the VHH were observed. The average qP at the end of the retentostat was estimated at 0.019 mg g−1 h−1. Transcriptomics indicated that genes involved in protein biosynthesis were only moderately downregulated towards zero growth, while secretory pathway genes were mostly regulated in a manner seemingly detrimental to protein secretion. Adaptation to near-zero growth conditions of recombinant K. phaffii resulted in significant changes in the total protein, RNA, DNA and lipid content, and lipidomics revealed a complex adaptation pattern regarding the lipid class composition. The higher abundance of storage lipids as well as storage carbohydrates indicates that the cells are preparing for long-term survival.ConclusionsIn conclusion, retentostat cultivation proved to be a valuable tool to identify potential engineering targets to decouple growth and protein production and gain important insights into the physiological adaptation of K. phaffii to near-zero growth conditions.

Lipid species profiling of bronchoalveolar lavage fluid cells of horses housed on two different bedding materials

The lipidome of equine BALF cells has not been described. The objectives of this prospective repeated-measures study were to explore the BALF cells’ lipidome in horses and to identify lipids associated with progression or resolution of airway inflammation. BALF cells from 22 horses exposed to two bedding materials (Peat 1—Wood shavings [WS]—Peat 2) were studied by liquid chromatography-tandem mass spectrometry (LC–MS/MS). The effects of bedding on lipid class and species compositions were tested with rmANOVA. Correlations between lipids and cell counts were examined. The BALF cells’ lipidome showed bedding-related differences for molar percentage (mol%) of 60 species. Whole phosphatidylcholine (PC) class and its species PC 32:0 (main molecular species 16:0_16:0) had higher mol% after Peat 2 compared with WS. Phosphatidylinositol 38:4 (main molecular species 18:0_20:4) was higher after WS compared with both peat periods. BALF cell count correlated positively with mol% of the lipid classes phosphatidylserine, sphingomyelin, ceramide, hexosylceramide, and triacylglycerol but negatively with PC. BALF cell count correlated positively with phosphatidylinositol 38:4 mol%. In conclusion, equine BALF cells’ lipid profiles explored with MS-based lipidomics indicated subclinical inflammatory changes after WS. Inflammatory reactions in the cellular lipid species composition were detected although cytological responses indicating inflammation were weak.

Fatty Acid and Amino Acid Profiles of Seven Edible Insects: Focus on Lipid Class Composition and Protein Conversion Factors.

This study is based on the fatty acid and amino acid profiles of seven edible insect species: Acheta domesticus, Alphitobius diaperinus, Blaptica dubia, Galleria mellonella, Locusta migratoria, Tenebrio molitor, and Zophobas morio. The aim of the present study is to provide new data on the fatty acid distributions among lipid classes as well as the species-specific protein conversion factor (Kp) of a wide range of insects in order to further improve the nutritional characterisation of insects as food. Oleic acid was the predominant fatty acid in all insects except for A. domesticus, in which a significantly higher percentage of linoleic acid was found. The majority of the lipids were neutral lipids. A significant amount of α-linolenic acid in the phospholipid fraction of L. migratoria was shown, while in T. molitor, phospholipids were the only fraction in which a measurable amount of docosahexaenoic acid was found. Overall, in most insects, the phospholipid fraction had the highest polyunsaturated fatty acid content compared to the other classes, which may be protective in terms of auto-oxidative stability. Kp values in the range of 4.17 to 6.43 were obtained. Within the nutritional quality indices, all insects showed healthy fatty acids and high-quality amino acid profiles.

Seasonal effect on fatty acid composition in phospholipid classes and triacylglycerols of male Capoeta umbla

The seasonal changes in muscle tissue, total lipids and fatty acid composition of phospholipids (PL), triacylglycerol (TAG), and phospholipid classes of male Capoeta umbla were investigated in this study. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylserine (PS) were identified as the major phospholipids (PLs) in the muscle tissue (PS). Triacylglycerols showed high contents of MUFA, 14:0, 16:1n-7, 18:1n-9, 18:2n-6, and 18:3n-3; while phospholipids presented high contents of AA, DHA, and 18:0. Myristic acid, 16:1n-7, 18:1n-9, monounsaturated fatty acids (MUFA), linoleic acid (18:2n-6), and linolenic acid (18:3n-3) were shown to be present in larger concentrations in TAG than in PL classes. In PL classes, 16:0, 18:0, arachidonic acid (20:4n-6) (AA), eicosapentaenoic acid (EPA) (20:5n-3), docosahexaenoic acid (DHA) (22:6n-3) and polyunsaturated fatty acid (ΣPUFA) were higher than the TAG fraction. The fatty acid composition of total lipid and lipid classes (TAG and PL) were affected by the seasonal variations and lipid fraction.

Comparative studies on the lipid profiles of female and male gonads of abalone (Haliotis discus hannai)

AbstractLipid profiles of the lipids from female gonads (LFG) and male gonads (LMG) of abalones (Haliotis discus hannai) were evaluated based on the analysis of phospholipid (PL) molecular species, PL class composition, fatty acid (FA) composition, and lipid class composition. These results suggested that lipids from abalone gonads were abundant in omega‐3 polyunsaturated FA (n − 3 PUFA, 14.42%–18.27% of total FAs) and PLs including phosphatidylcholine (PC, 21.26–47.85 mg g−1) and phosphatidylethanolamine (PE, 9.29–24.10 mg g−1). Furthermore, more than 60 molecular species of PC and PE were determined. Particularly, the molecular species containing n − 3 PUFA including eicosapentaenoic acid (EPA) constituted majority of PC and PE in LFG and LMG. By contrast, LFG contained more PC and PE species containing EPA. Considering the lipid profiles, abalone gonads are a potential source of PL‐form n − 3 PUFA.

Single-nucleus and bulk RNA sequencing reveal cellular and transcriptional mechanisms underlying lipid dynamics in high marbled pork

Pork is the most consumed meat in the world, and its quality is associated with human health. Intramuscular fat (IMF) deposition (also called marbling) is a key factor positively correlated with various quality traits and lipo-nutritional values of meat. However, the cell dynamics and transcriptional programs underlying lipid deposition in highly marbled meat are still unclear. Here, we used Laiwu pigs with high (HLW) or low (LLW) IMF contents to explore the cellular and transcriptional mechanisms underlying lipid deposition in highly-marbled pork by single-nucleus RNA sequencing (snRNA-seq) and bulk RNA sequencing. The HLW group had higher IMF contents but less drip loss than the LLW group. Lipidomics results revelled the changes of overall lipid classes composition (e.g., glycerolipids including triglycerides, diglycerides, and monoglycerides; sphingolipids including ceramides and monohexose ceramide significantly increased) between HLW and LLW groups. SnRNA-seq revealed nine distinct cell clusters, and the HLW group had a higher percentage of adipocytes (1.40% vs. 0.17%) than the LLW group. We identified 3 subpopulations of adipocytes, including PDE4D+/PDE7B+ (in HLW and LLW), DGAT2+/SCD+ (mostly in HLW) and FABP5+/SIAH1+ cells (mostly in HLW). Moreover, we showed that fibro/adipogenic progenitors could differentiate into IMF cells and contribute to 43.35% of adipocytes in mice. In addition, RNA-seq revealed different genes involved in lipid metabolism and fatty acid elongation. Our study provides new insights into the cellular and molecular signatures of marbling formation; such knowledge may facilitate the development of new strategies to increase IMF deposition and the lipo-nutritional quality of high marbled pork.

Tea polyphenol EGCG ameliorates obesity-related complications by regulating lipidomic pathway in leptin receptor knockout rats

Tea polyphenol epigallocatechin-3-gallate (EGCG) has been widely recognized for antiobesity effects. However, the molecular mechanism of lipidomic pathway related to lipid-lowering effect of EGCG is still not well understood. The aim of this study was to investigate the effects and mechanism of EGCG activated hepatic lipidomic pathways on ameliorating obesity-related complications by using newly developed leptin receptor knockout (Lepr KO) rats. Results showed that EGCG supplementation (100 mg/kg body weight) significantly decreased total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) levels both in the serum and liver, and significantly improved glucose intolerance. In addition, EGCG alleviated fatty liver development and restored the normal liver function in Lepr KO rats. Liver lipidomic analysis revealed that EGCG dramatically changes overall composition of lipid classes. Notably, EGCG significantly decreased an array of triglycerides (TGs) and diglycerides (DGs) levels. While EGCG increased 31 glycerophospholipid species and one sphingolipid species levels, such as phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), phosphatidylserines (PSs) and phosphatidylinositols (PIs) levels in the liver of Lepr KO rats. Moreover, 14 diversely regulated lipid species were identified as potential lipid biomarkers. Mechanistic analysis revealed that EGCG significantly activated the SIRT6/AMPK/SREBP1/FAS pathway to decrease DGs and TGs levels and upregulated glycerophospholipids synthesis pathways to increase glycerophospholipid level in the liver of Lepr KO rats. These findings suggested that the regulation of glycerolipids and glycerophospholipid homeostasis might be the key pathways for EGCG in ameliorating obesity-related complications in Lepr KO rats.

Effects of Replacement of Fish Oil with Microbial Oil (Schizochytrium sp. T18) on Membrane Lipid Composition of Atlantic Salmon Parr Muscle and Liver Tissues

A 16-week feeding trial was conducted to investigate effects of replacing dietary fish oil (FO) with docosahexaenoic acid (DHA)-rich microbial oil (MO) from Schizochytrium sp. (T18) on membrane lipid composition of Atlantic salmon parr liver and muscle tissues. Four nutritionally balanced diets were formulated with varying levels of FO, MO, and canola oil (CO), including a control diet with 20% FO, a secondary control diet with 10% FO and 10% CO, and two experimental diets that completely replaced FO with a low (5%) and high (10%) proportion of MO. No significant differences were observed in growth parameters (81–98 g; weight gain), total lipid class composition, and total sterol content among the dietary treatments. However, there were significant differences in the proportions of individual ꞷ3 and ꞷ6 fatty acids in both liver and muscle tissues, reflecting the different dietary treatments. Notably, the presence of low eicosapentaenoic acid (EPA) in the MO diets did not affect the growth performance of the fish, suggesting a lower requirement for EPA in the diet and a greater necessity for DHA. The results also showed that DHA was present in very high proportions in the cellular membrane, particularly in muscle tissue, with low levels of linoleic acid and alpha-linolenic acid. Overall, the findings suggest that MO derived from Schizochytrium sp. (T18) could be a potential substitute for FO in the diet of farmed Atlantic salmon.

Similarities in biomass and energy reserves among coral colonies from contrasting reef environments

Coral reefs are declining worldwide, yet some coral populations are better adapted to withstand reductions in pH and the rising frequency of marine heatwaves. The nearshore reef habitats of Palau, Micronesia are a proxy for a future of warmer, more acidic oceans. Coral populations in these habitats can resist, and recover from, episodes of thermal stress better than offshore conspecifics. To explore the physiological basis of this tolerance, we compared tissue biomass (ash-free dry weight cm−2), energy reserves (i.e., protein, total lipid, carbohydrate content), and several important lipid classes in six coral species living in both offshore and nearshore environments. In contrast to expectations, a trend emerged of many nearshore colonies exhibiting lower biomass and energy reserves than colonies from offshore sites, which may be explained by the increased metabolic demand of living in a warmer, acidic, environment. Despite hosting different dinoflagellate symbiont species and having access to contrasting prey abundances, total lipid and lipid class compositions were similar in colonies from each habitat. Ultimately, while the regulation of colony biomass and energy reserves may be influenced by factors, including the identity of the resident symbiont, kind of food consumed, and host genetic attributes, these independent processes converged to a similar homeostatic set point under different environmental conditions.

Lipidomic Profiling of Rice Bran after Green Solid-Liquid Extractions for the Development of Circular Economy Approaches.

Rice bran is a rather underutilized by-product of the rice industry that nowadays is far from being valorized. In this study, the lipidomic profile of bran of the Italian rice variety, Roma, has been evaluated through ultra performance liquid chromatography-tandem mass spectrometry. Crude lipid extracts were obtained from rice bran treated with different green solvents (1-butanol, ethanol and methyl tert-butyl ether/methanol mixture) in combination with an ultrasonic pre-treatment, and then compared with extracts obtained with standard solvents (chloroform/methanol mixture). Lipid yield, number and type of lipids and composition of prevalent lipid classes extracted were evaluated in order to provide an exhaustive lipid profile of the rice bran and to identify the most efficient green solvent for solid-liquid extractions. Twelve different lipid classes and a maximum of 276 lipids were identified. Ethanol and methyl tert-butyl ether/methanol solvents provided higher lipid extraction yields, the former being the most effective solvent for the extraction of triglycerides and N-acylethanolamines and the latter the most effective for the extraction of diglycerides, phospholipids and ceramides at 4 °C. Moreover, extraction with ethanol at 20 °C gave similar results as at 4 °C in terms of lipid yield and for most of the classes of lipids extracted. Taken together, our results indicate ethanol and methyl tert-butyl ether/methanol as excellent solvents for lipid extraction from rice bran, with the aim to further valorize this food by-product in the perspective of a circular economy.

Characterization and Antioxidant Evaluation of Four Kinds of Marine Oils in vitro.

The objective of this study was to characterize the lipid class and fatty acid composition of four kinds of marine oils including Phaeodactylum tricornutum oil (PO), Laminaria japonica oil (LO), krill oil (KO) and fish oil (FO), and evaluate their antioxidant capacities in vitro. The results indicated that compared to other three oils, PO showed the highest contents of total lipids and fucoxanthin (194.70 and 7.48 mg/g dry weight, respectively), the relatively higher content of long-chain polyunsaturated fatty acids including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (30.94 % in total fatty acids), and total phenolic content (675.88 mg gallic acid equivalent /100 g lipids), thereby contribute to great advantages in scavenging free radicals such as 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2-azino-bis (3-ethylbenzthiazoline)-6-sulfonic acid (ABTS), peroxyl radical, as well as reducing FRAP value. In conclusion, PO should be considered as a potential ingredient for dietary supplement with antioxidant capacity.

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.

Antioxidative capacity of microalgal carotenoids for stabilizing n-3 LC-PUFA rich oil: Initial quantity is key

The health-beneficial long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFA) are easily affected by the undesired process of lipid oxidation in fish oil, while being stable in the lipid extracts of photoautotrophic microalgae. The current research investigates the role of carotenoids by evaluating the oxidative stability of mixtures of fish oil with total lipid extracts of two different microalgae (Phaeodactylum and Isochrysis) throughout an accelerated storage experiment of 4 weeks at 37 °C. A clear separation between oxidatively stable and oxidatively unstable mixtures was observed for which the initial amount of carotenoids relative to the amount of n-3LC-PUFA was a good indicator. The lipid class composition, clearly differing between the two algae, was probably of minor influence. The antioxidative role of fucoxanthin, and diatoxanthin and β–carotene as minor carotenoids, was illustrated by their gradual degradation throughout storage. However, when their initial contents were too low, this role could not be exerted leading to thorough lipid oxidation.