Composition Of Milk Fat Globule Membrane Research Articles

Lipidomic and proteomic profiling identifies the milk fat globule membrane composition of milk from cows and camels

This study was designed to detect lipidomic and proteomic differences in the milk fat globule membrane (MFGM) fractions of cow and camel milk samples. In total, 353 lipid species were detected in these analyses, including 77 PEs, 30 PCs, 28 PIs, 59 SMs, 54 Cers, 13 LPCs, 14 LPEs, 20 PSs, and 4 PGs. These included 54 polar lipid species that differed significantly in abundance between cow and camel milk. Glycerophospholipid metabolism was identified as a core metabolic pathway associated with camel milk composition. Furthermore, 547 proteins exhibiting differential abundance were identified by a label-free proteomics methodology when comparing samples of MFGMfrom camels and cows. Of these proteins, those that differed most in expression between these groups were associated with metabolic pathways, including endoplasmic reticulum activity, endocytosis, and PI3K-Akt signaling. In conclusion, our findings provide a more thorough understanding of the composition of MFGM and its physiological significance, hence offering robust evidence for the potential utilization of camel milk as a nutritional resource in future developments.

The effect of high-pressure homogenisation on the size of milk fat globules and MFGM composition in sweet buttermilk and milk

Effects of high-pressure homogenisation (HPH, 100 MPa) at different temperatures (4–60 °C) or conventional homogenisation (20 MPa, 60 °C) on size of milk fat globules (D32) and content of protein and phospholipids in milk fat globule membrane (MFGM) in standardised milk, buttermilk and a mixture of milk and buttermilk were compared. HPH decreased D32 and promoted the adsorption of casein at ≥ 4 °C, β-lactoglobulin in milk and buttermilk at ≥ 40 °C and ≥20 °C, respectively, and α-lactalbumin at 60 °C, on the surface of milk fat globules. The content of milk proteins adsorbed on MFGM increased with increasing temperature and pressure in milk, and, to a lesser extent, in buttermilk. The content of phospholipids in buttermilk was 2-fold higher than in milk. HPH influenced the content of sphingomyelin (increased) and phosphatidylcholine (decreased) in MFGM in milk. Conventional homogenisation increased the phosphatidylethanolamine content in MFGM in buttermilk.

Lipid Metabolism in Mammary Epithelial Cells-A Comparison of Common In vitro Models

One of the main cellular functions of mammary epithelial cells (MEC) is the vast production of lipids to provide the new born with the energy and bioactive molecules that are essential for its development and survival. Milk lipids are secreted in a structure termed milk fat globule (MFG) which buds from the MEC, enveloped with the cellular bilayer membrane. MFG membrane composition changes as a function of lactation stage, nutrition and MFG size. In addition, MFG size differs at different stages of lactation and in response to nutritional treatments. Therefore, it is hypothesized that the MEC membrane changes according to metabolic and hormonal signals in the animal's body, and that these changes are associated with milk lipid production and secretion and MFG size. The aim of this work was to find a suitable model for studying lipogenic activity and its relation to membrane composition in the mammary gland. Two in vitro models were compared: mammary gland tissue culture ('explants') and primary culture of MEC. Prolactin treatment increased fat concentration in the explants. In addition, conjugated linoleic acid decreased fat content, but only in the presence of prolactin. Despite these interesting results, the model was not reproducible. Cells of the primary MEC culture showed cytokeratin-18 mRNA and protein expression, which validated the culture's epithelial content. In addition, this model was prolactin-sensitive, as reflected by induction of α-lactalbumin expression in response to prolactin administration. Oleic acid induced the formation of large lipid droplets, and methionine addition to the oleic acid treatment further increased lipid droplet size. In conclusion, primary culture of bovine MEC was found as an appropriate model for studying lipogenic activity with a focus on membrane composition and lipid droplet size in the mammary gland.

The antiproliferative properties of the milk fat globule membrane are affected by extensive heating

The milk fat globule membrane (MFGM), the material surrounding milk fat globules, is not only interesting from a technological standpoint but it also shows great potential as a health ingredient, as it exerts cytotoxic and apoptotic effects against colon cancer cells. Although the effects of milk processing on the MFGM composition and functionality are well documented, less is understood on how processing may affect its bioactivity. This study aimed to determine if heating can affect the antiproliferative capacity of the MFGM. To do so, MFGM was extracted from milk heated at 80 °C for 10 min, as this temperature/time regime is known to cause extensive protein-protein interactions with changes in the processing functionality of milk. Two cell lines, whose morphological features are representative of two different stages of colon carcinogenesis (HT-29 and Caco-2), were used to test the antiproliferative capacity of MFGM isolates obtained either from untreated or heated milk. Cell proliferation analysis showed a similar dose-dependent decrease of DNA synthesis in both cell lines exposed to 6.25–200 μg of MFGM protein.mL−1, isolated from unheated milk. The heat treatment diminished the efficacy of the MFGM isolates, as only the highest concentrations of MFGM tested following heating showed a significant effect on cell proliferation. The decreased ability of MFGM isolates to affect the carcinoma cell proliferation was attributed to changes in composition, mainly phospholipid losses. Changes to the supramolecular structure of the MFGM caused by heating may also have played a role. This work demonstrates the importance of processing history in assessing the biological functionality of MFGM.

Milk Fat Globule Membrane Composition and Dietary Change: Supplements of Coconut Oil Fed in Two Physical Forms

Milk fat globule membrane composition was compared in two diets, E and F. Both contained coconut oil supplement emulsified with casein, but in diet F the supplement had been treated with formaldehyde. More membrane was secreted in diet E, and it contained a greater proportion of neutral lipid and a lower proportion of protein than diet F. No difference in neutral lipid fatty acid composition of membrane was observed between diets E and F. The amounts of coconut oil fatty acids in membrane neutral lipids were higher in diets E and F than in a ration containing no coconut oil. Individual phospholipids were unaffected by diet, and no incorporation of the supplemented lipid into membrane polar lipids occurred. Proportions of major membrane proteins changed as shown by sodium dodecyl sulphate-polyacrylamide gel electrophoresis.