Effect of washing conditions on the recovery of milk fat globule membrane proteins during the isolation of milk fat globule membrane from milk (original) (raw)
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Composition, Properties and Nutritional Aspects of Milk Fat Globule Membrane - a Review
Polish Journal of Food and Nutrition Sciences, 2000
In the last few years, knowledge on the composition and properties of the milk fat globule membrane (MFGM) increased significantly. It is now recognized that the MFGM is highly complex in structure and composed of different protein and lipid components with specific technological and nutritional properties. As such, MFGM materials have been isolated and characterized as valuable ingredients for incorporation into new food products. However, MFGM are also sensitive to modification during isolation and processing, and care should be taken to standardize the composition and characteristics of the membrane to maintain its unique properties during application in food products. The MFGM is subject to changes in composition and structure from the moment the fat globule leaves the mammary secretory cell. Upon milk harvesting and further milk handling, further changes to the MFGM take place. Depending on the type and degree of treatment, this may involve different physico-chemical interactions between various membrane components, the loss of membrane components and/or adsorption of components from the milk plasma. However, the effects appear to be variable and dependent on physiological (animal) factors, and much remains to be learned about the phenomena on a molecular level. Review Article Section: Food Chemistry
The milk fat globule membrane as an ingredient: why, how, when?
Dairy Science and Technology, 2008
This paper presents a personal view on the potential applications of the milk fat globule membrane as an ingredient in the processed foods area. Several factors are of importance for this dissertation: the biological origin of the membrane, the voluminous literature on its individual components and their relationship with health and wellness, the biological role of milk in nutrition to mammals and the innovation on scientific tools being applied in many fields of chemistry and biology. We hope to give a glimpse of the reasons on why it is a good idea to use more efficiently the components of the milk fat globule membrane. In addition we consider current advances in the fractionation of milk components to propose how this ingredient can be produced. However, we leave the timing question, when?, open for discussion in the different scientific and technological fields. milk fat globule membrane (MFGM) / isolation / analytical tools / biological activities
Nutritional and technological aspects of milk fat globule membrane material
International Dairy Journal, 2008
The milk fat globule membrane (MFGM) has gained a lot of attention recently, due to the growing interest in its nutritional and technological properties. The whole membrane as well as the separate lipid and protein components have great potential for new product applications with unique nutritional and technological properties. This review focuses on the nutritional and technological aspects of the MFGM material, but also gives an overview of the gathered information about the composition, structure and isolation methods of the MFGM from different dairy sources. r
Characterization of protein components of natural and heat-treated milk fat globule membranes
International Dairy Journal, 2002
The proteins associated with the milk fat globule membrane (MFGM), isolated from early, mid and late season whole milks, were characterized using one-and two-dimensional SDS-PAGE under reducing and non-reducing conditions. In some experiments, MFGM separated from fresh whole milk was suspended in simulated milk ultrafiltrate (SMUF) and heated at various temperatures and times. SDS-PAGE under reducing conditions followed by staining with Coomassie blue showed the presence of about 37 protein bands, ranging in molecular weight from 15 to 200 kDa. SDS-PAGE under non-reducing conditions showed only about 25 distinct bands and the intensity of xanthine oxidase and butyrophilin bands was much less, while the intensity of PAS 6/7 band was similar compared with the reduced SDS-PAGE. Two-dimensional SDS-PAGE showed that the protein complexes that remained at the top of non-reducing gel were resolved into mostly xanthine oxidase and butyrophilin with a small proportion of PAS 6. These results indicate that xanthine oxidase and butyrophilin may be complexed via intermolecular disulfide bonds in the natural MFGM, although it is not possible to differentiate the individual protein distributions within these aggregates. It was found that the total protein content (mg/g fat) of MFGM and the percentage of xanthine oxidase and butyrophilin in early and late season MFGM were higher than that of mid season MFGM. In heated samples (above 601C), xanthine oxidase and butyrophilin interacted further to form higher molecular weight protein complexes, while PAS 6/7 was relatively heat stable.
International Dairy Journal, 2011
Isolated milk fat globules were subjected to enzyme hydrolysis by a specific protease (trypsin) and a nonspecific protease (pronase E) to study the asymmetric arrangement of milk fat globule membrane (MFGM) proteins. The remaining proteins on the globules after proteolysis were resolved by two-dimensional gel electrophoresis and identified by mass spectrometry. By this proteomic approach, the results confirmed different susceptibility of the MFGM proteins to proteolysis by enzymes. Butyrophilin and adipophilin were completely digested by trypsin and by pronase E, whereas lactadherin and xanthine dehydrogenase/ oxidase were almost resistant to hydrolysis by trypsin and partially attacked by pronase E. Based on our results and recent bibliographic data, an updated model of the organization of some MFGM proteins is proposed and discussed.
Separation of the proteins of bovine milk-fat globule membrane by electrofocusing
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1978
The proteins of milk-fat globule membrane have been separated by electrofocusing on both the analytical and preparative scale. Over forty separated proteins of the membrane can be identified after electrofocusing in the presence of urea, Triton X-100 and mercaptoethanol with apparent isoelectric points between pH 5.0 and 9.0. At least eight of these proteins appear to contain carbohydrate. After separation by electrofocusing the samples have been further analyzed by electrophoresis in polyacrylamide gels containing sodium dodecyl sulphate. Some of the proteins previously identified as single bands by electrophoresis in SDS are resolved into several components by electrofocusing. The major components of milk-fat globule membrane are a glycoprotein of 67 000 daltons, with an apparent isoelectric point of 5.55, and a protein of 155 000 daltons with an isoelectric point of 7.6. Partially purified fractions of the major proteins and glycoproteins can be obtained after preparative electrofocusing in flat-beds of Sephadex G-75.
Filtration of Milk Fat Globule Membrane Fragments from Acid Buttermilk Cheese Whey
Journal of Dairy Science, 2007
The proteins and polar lipids present in milk fat globule membrane (MFGM) fragments are gaining attention for their technological and nutritional properties. These MFGM fragments are preferentially enriched in side streams of the dairy industry, like butter serum, buttermilk, and whey. The objective of this study was to recover MFGM fragments from whey by tangential filtration techniques. Acid buttermilk cheese whey was chosen as a source for purification by tangential membrane filtration because it is relatively rich in MFGMfragments and because casein micelles are absent. Polyethersulfone and cellulose acetate membranes of different pore sizes were evaluated on polar lipid and MFGMprotein retention upon filtration at 40°C. All fractions were analyzed for dry matter, ash, lipids, proteins, reducing sugars, polar lipid content by HPLC, and for the presence of MFGM proteins by sodium dodecyl sulfate-PAGE. A fouling coefficient was calculated. It was found that a thermocalcic aggregation whey pretreatment was very effective in the clarification of the whey, but resulted in low permeate fluxes and high retention of ash and whey proteins. By means of an experimental design, the influence of pH and temperature on the fouling and the retention of polar lipids (and thus MFGM fragments), proteins, and total lipids upon microfiltration with 0.15 M cellulose acetate membrane was investigated. All models were highly significant, and no outliers were observed. By increasing the pH from 4.6 to 7.5, polar lipid retention at 50°C increased from 64 to 98%, whereas fouling of the filtration membrane was minimized. A 3-step diafiltration of acid whey under these conditions resulted in a polar lipid concentration of 6.79 g/100 g of dry matter. As such, this study shows that tangential filtration techniques are suited for the purification of MFGM fragments.
Fractionation and characterization of the membranes from bovine milk fat globules
Journal of Dairy Research, 1977
Bovine milk-fat globule membrane (MFGM) has been fractionated into 3 membrane components by isopycnic sucrose density gradient centrifugation. The 3 components, designated as heavy, medium and light material, were characterized by particular polypeptide, lipid, carbohydrate and enzyme compositions. The heavy material (density > 1-145 g/ml) was red-brown in appearance and consisted of 63 % protein, 32 % lipid and 5 % carbohydrate. The lipid moiety contained 40% triglyceride and 60% phospholipid, while the protein consisted of 3 major polypeptides (apparent mol. wt 135000, 70000 and 53000) in the ratio of 3:6:1. This membrane class was also characterized by the presence of both xanthine oxidase and acid phosphatase. The medium density material (density 1-055-1-145 g/ml) was light red to pink in colour and consisted of 35 % protein, 58 % lipid and 6 % carbohydrate. The lipid contained 45 % triglyceride and 55 % phospholipid, with nearly 70 % of the original MFGM phospholipid being found in this material. The ratio of the 3 major polypeptide bands was 2:4:4 and high levels of both alkaline phosphatase and 5'-nucleotidase were present. The light material (density < 1-055 g/ml) was white to pale pink in colour and was composed of 88% lipid of which 94 % was triglyceride, together with 8 % protein and 4 % carbohydrate. There were virtually no enzymes present and 70 % of the protein consisted of a polypeptide with apparent mol. wtof 53000. The 3 membrane classes also differed in carbohydrate content and in the fatty acid composition of their triglycerides.
Studies on milk fat globule membranes
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1967
The fat globules in milk are surrounded by a membranous envelope about 9 ° A thick. Ghosts can be formed by freeze-thawing or sonication. Membrane preparations were found to contain alkaline phosphomonoesterase, acid phosphomonoesterase, phosphodiesterase, glucose-6-phosphatase, Mg~+-activated ATPase, (Na+-K+-Mg2+)activated ATPase, true cholinesterase, xanthine oxidase and aldolase. In the main, the enzyme activities found in the fat globule membranes are found in the fraction of other tissues thought to contain plasma membranes. Enzymes characteristic of other tissue fractions were generally absent from the fat globule membranes. Antisera to fat globule membranes agglutinated and hemolyzed bovine erythrocytes. The fat globules appear to be freely permeable to potassium. The fat globule membrane appears to be a derivative of the cell membrane of the mammary cells.