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• Application of structured illumination microscopy to examine milk ultrastructure. • Pasteurization significantly impacts PC and SM in the outer membrane. • Heat treatment reduces glycerolipids with AA/DHA and glycerophospholipids. • Addition of phospholipids and freeze-drying enhance polar lipid content. • SIM effectively displays nanoscale changes in fat globules during processing. The introduction of exogenous lipids in the production of infant formula induces significant alterations in milk lipid composition, content, and membrane structure, thus affecting the lipid digestion, absorption, and utilization. This study meticulously tracks these changes throughout the manufacturing process. Pasteurization has a significant effect on phosphatidylcholine and sphingomyelin in the outer membrane, decreasing their relative contents to total polar lipids from 12.52% and 17.34% to 7.72% and 12.59%, respectively. Subsequent processes, including bactericidal-concentration and spray-drying, demonstrate the thermal stability of sphingomyelin and ceramides, while glycerolipids with arachidonic acid/docosahexaenoic acid and glycerophospholipids, particularly phosphatidylethanolamine, diminish significantly. Polar lipids addition and freeze-drying technology significantly enhance the polar lipid content and improve microscopic morphology of infant formula. These findings reveal the diverse effects of technological processes on glycerolipid and polar lipid compositions, concentration, and ultrastructure in infant formulas, thus offering crucial insights for optimizing lipid content and structure within infant formula. [ABSTRACT FROM AUTHOR]

Reverse osmosis with polyamide spiral wound membranes is used to concentrate milk to reduce its volume before transport to processing facilities. The main aim of this work was to identify the cause of unusually low flux through a membrane that had been used in an industrial facility. The fluxes of new and used industrial membranes were measured using a flat-sheet cross-flow laboratory system. It was found that the fouling characteristics of laboratory fouled membranes were entirely different from the industrial membrane. The laboratory membranes could be restored to a high flux with a regime of water flushing, caustic and acid. FTIR showed no significant build-up on the membrane. In contrast the industrial membrane could not be cleaned in this manner. FTIR and FT-Raman showed species associated with milk lipids. Cleaning by solvent extraction using a two-phase mixture of water, isopropanol and cyclohexane increased the flux from 1% to almost 50% of the value of a new membrane. Analysis of the solvent-extracted material indicated the presence of phospholipids with a relatively high concentration of sphingomyelin. It was concluded that the laboratory experiments did not mimic industrial processes and an effective industrial cleaning system was not found. [ABSTRACT FROM AUTHOR]

• Metabolomics and lipidomics were employed to analysis raw milk quality of cows. • Subclinical ketosis affected the profiles of metabolites and lipid species. • Subclinical ketosis cows had lower percentage of PUFA and CLA than healthy cows. • Fifteen volatiles were identified to be correlated with the health status of cows. • The nutritional quality of milk of subclinical ketosis cows were reduced. The metabolic status of dairy cows directly influences the nutritional quality and flavor of raw milk. A comprehensive comparison of non-volatile metabolites and volatile compounds in raw milk from healthy and subclinical ketosis (SCK) cows was performed using LC–MS, GC-FID, and HS-SPME/GC–MS. SCK can significantly alter the profiles of water-soluble non-volatile metabolites, lipids, and volatile compounds of raw milk. Compared with healthy cows, milk from SCK cows had higher contents of tyrosine, leucine, isoleucine, galactose-1-phosphate, carnitine, citrate, phosphatidylethanolamine species, acetone, 2-butanone, hexanal, dimethyl disulfide and lower content of creatinine, taurine, choline, α-ketoglutaric acid, fumarate, triglyceride species, ethyl butanoate, ethyl acetate, and heptanal. The percentage of polyunsaturated fatty acids in milk was lowered in SCK cows. Our results suggest that SCK can change milk metabolite profiles, disrupt the lipid composition of milk fat globule membrane, decrease the nutritional value, and increase the volatile compounds associated with off-flavors in milk. [ABSTRACT FROM AUTHOR]

[Display omitted] The milk fat globule membrane (MFGM) provides infants and adults with several health benefits. These are not derived solely from its unique composition, but also from arrangement of lipids in the MFGM that, in the case of newborns, could reach the intestine partially intact. Fluorochromes associated with lipid derivatives were used to prove a fusion process between the MFGM and the cellular membrane of differentiated Caco-2 cells. To explore the mechanism of this interaction, incubations of MFGM with Caco-2 cells were carried out in the presence of fusogenic agents or compounds that block other MFGM interaction pathways with cells. Confocal fluorescence microscopy provided visual evidence of the fusion process. Lastly, determination on the lipid profile of cells after their interaction with MFGM indicated a metabolic rearrangement of lipids leading to accumulation of triacylglycerols. [ABSTRACT FROM AUTHOR]

The naturally occurring milk sphingomyelin is of particular interest owing to its complex composition and involvement in the formation of the milk fat globule membrane (MFGM). Knowledge of membrane organization and nanomechanical stability has proved to be crucial in understanding their properties and functions. In this work, two model membrane systems composed of 1, 2 dioleoyl- sn -glycero-3-phosphocholine (DOPC), egg sphingomyelin (egg-SM) and cholesterol, and DOPC, milk sphingomyelin (milk-SM) and cholesterol were exposed to both RT and 10 °C. The morphological and nanomechanical changes were investigated using atomic force microscopy (AFM) imaging and force mapping below RT using a designed liquid cell with temperature-control. In both systems, the size and shape of SM/Chol-enriched liquid ordered domains (L o ) and DOPC-enriched liquid disordered phase (L d ) were monitored at controlled temperatures. AFM based force-mapping showed that rupture forces were consistently higher for L o domains than L d phases and were decreased for L d with decreasing temperature while an increase in breakthrough force was observed in L o domains. More interestingly, dynamic changes and defect formations in the hydrated lipid bilayers were mostly detected at low temperature, suggesting a rearrangement of lipid molecules to relieve additional tension introduced upon cooling. Noteworthy, in these model membrane systems, tension-driven defects generally heal on reheating the sample. The results of this work bring new insights to low temperature induced membrane structural reorganization and mechanical stability changes which will bring us one step closer to understand more complex systems such as the MFGM. [ABSTRACT FROM AUTHOR]

• Identification of 1302 molecular species in bovine milk. • Seasonal and feeding-related differences between hay and regular milk. • Short- and medium-odd chain TGs were upregulated in hay milk during summer. • Short- and medium-even chain TGs increased in regular milk during spring and winter. • Lipidomes in hay and regular milk were different along the industrial processing. Bovine milk plays an important role in human nutrition and is one of the main products of dairy industry. Its composition changes in response to various factors including forage, which are rapidly reflected by the milk lipidome. Most cows receive a silage-based diet despite a recent trend towards more traditional husbandry relying on hay-feeding. Here, changes in the lipidome upon different animal diets were addressed by studying milk of cows from two different feeding regimes and associated seasonal variations over one year. Extracted lipids were analyzed by reversed-phase liquid chromatography coupled on-line to high resolution mass spectrometry. Overall, 1302 lipid molecular species were identified including 1038 triacylglycerides (∼80%), whereas the remaining 20% were represented by a variety of species from twelve lipid classes. A semi-absolute quantitation of 264 lipid species showed diet- and season-induced variations in the milk lipidome with many odd chain triacylglycerides upregulated in hay milk. [ABSTRACT FROM AUTHOR]

Highlights: [•] GC×GC–MS/FID was used for the analysis of the unsaponifiable fraction of milk lipids. [•] The structure of many constituents was confirmed by using GC–high resolution ToF MS. [•] Sensitivity and group-type patterns were the GC×GC characteristics most exploited. [ABSTRACT FROM AUTHOR]

Abstract: Milk has co-evolved with mammals and mankind to nourish their offspring and is a biological fluid of unique complexity and richness. It contains all necessary nutrients for the growth and development of the newborn. Structure and function of biomolecules in milk such as the macronutrients (glyco-) proteins, lipids, and oligosaccharides are central topics in nutritional research. Omics disciplines such as proteomics, glycomics, glycoproteomics, and lipidomics enable comprehensive analysis of these biomolecule components in food science and industry. Mass spectrometry has largely expanded our knowledge on these milk bioactives as it enables identification, quantification and characterization of milk proteins, carbohydrates, and lipids. In this article, we describe the biological importance of milk macronutrients and review the application of proteomics, glycomics, glycoproteomics, and lipidomics to the analysis of milk. Proteomics is a central platform among the Omics tools that have more recently been adapted and applied to nutrition and health research in order to deliver biomarkers for health and comfort as well as to discover beneficial food bioactives. [Copyright &y& Elsevier]

• First adoption of Paterno-Buchi reaction in studying milk lipid fine structure. • Unsaturated fatty acids show a non-specific regio-distribution in phospholipids. • Regioisomers are widespread in milk phospholipid species. • Double-bond isomers of C18:1 and C18:2 are widely detected in milk phospholipids. Hundreds of phospholipid (PL) species with defined fatty acid (FA) composition have been identified previously in bovine milk using liquid chromatography tandem mass spectrometry (LC-MS/MS). Paterno-Buchi photochemical reaction coupled with LC-MS/MS was applied in this study to further unravel the regio-distribution and double bond (DB) locations of FAs. Using SPE-purified PLs and 2-acetylpyridine as the photochemical derivatization reagent, we were able to reveal the non-specific regio-distribution of unsaturated FAs and the widespread occurrence of regioisomers in milk PLs. Although Δ9 and Δ9,12 were found to be the predominant DB location(s) for C18:1 and C18:2 respectively, other DB positional isomers such as C18:1Δ11, C18:1Δ12 and C18:1Δ13 and C18:2Δ9,11 were widely detected in PL structures, implying that the minor isomers of C18:1 and C18:2 equally participate in the synthesis of PLs. Our study provides novel information on the fine structure of milk PLs and further underlines the complexity of milk lipid composition. [ABSTRACT FROM AUTHOR]

Our previous study showed vitamin E deficiency in newborns (69.7%) and mothers at term (85.9%) when the ratio between serum vitamin E in mg/dl and total lipids in g/dl was used as an indicator of vitamin E status. This study was conducted to determine the human milk content of vitamin E. During the first 12 days of lactation milk vitamin E levels remained almost constant (day 1, 0.68 mg/dl; day 12, 0.65 mg/dl), milk total lipid levels increased daily (day 1, 1.11 g/dl; day 12, 3.60 g/dl), and the ratio between milk vitamin E and total lipids dropped steadily (day 1, 1.3;day 12, 0.2). In spite of this drop in vitamin E status, it is unlikely that vitamin E availability will be affected in neonates, because normal neonates absorb milk fats well and this ability increases with age. [ABSTRACT FROM AUTHOR]