486. The action of the lecithinase of Bacillus cereus on the globule membrane of milk fat

1952 ◽  
Vol 19 (3) ◽  
pp. 311-315 ◽  
Author(s):  
M. Jean Stone
Keyword(s):  
Bacillus Cereus ◽  
Culture Filtrate ◽  
Microscopic Examination ◽  
Milk Fat ◽  
Marked Effect ◽  
Whole Milk ◽  
Free Choline ◽  
Fat Globule ◽  
Hydrolysis Of ◽  
Qualitative Estimation

An effect simulating broken cream in whole milk was produced when Bacillus cereus was grown in washed cream at 22° C. A similar but less marked effect was obtained when a concentrated culture filtrate of B. cereus was added to washed cream.Microscopic examination of washed cream to which B. cereus or its concentrated filtrate had been added showed that the fat-globule membranes had been broken down. The hydrolysis of lecithin in washed cream in which B. cereus had grown was demonstrated by qualitative estimation of free choline.Since these results could not be reproduced when a non-lecithinase-producing strain of B. cereus or its concentrated culture filtrate was added to washed cream, it appears that the hydrolysis of the lecithin of the fat-globule membrane is at least partly responsible for the formation of broken cream.

Chemical changes in bovine milk fat globule membrane caused by heat treatment and homogenization of whole milk

2002 ◽  
Vol 69 (4) ◽  
pp. 555-567 ◽  
Author(s):  
SUNG JE LEE ◽  
JOHN W. SHERBON
Keyword(s):  
Heat Treatment ◽  
Membrane Proteins ◽  
Milk Fat ◽  
Whey Proteins ◽  
Bovine Milk ◽  
Chemical Changes ◽  
Milk Fat Globule Membrane ◽  
Whole Milk ◽  
Milk Fat Globule ◽  
Fat Globule

The effects of heat treatment and homogenization of whole milk on chemical changes in the milk fat globule membrane (MFGM) were investigated. Heating at 80 °C for 3–18 min caused an incorporation of whey proteins, especially β-lactoglobulin (β-lg), into MFGM, thus increasing the protein content of the membrane and decreasing the lipid. SDS-PAGE showed that membrane glycoproteins, such as PAS-6 and PAS-7, had disappeared or were weakly stained in the gel due to heating of the milk. Heating also decreased free sulphydryl (SH) groups in the MFGM and increased disulphide (SS) groups, suggesting that incorporation of β-lg might be due to association with membrane proteins via disulphide bonds. In contrast, homogenization caused an adsorption of caseins to the MFGM but no binding of whey proteins to the MFGM without heating. Binding of caseins and whey proteins and loss of membrane proteins were not significantly different between milk samples that were homogenized before and after heating. Viscosity of whole milk was increased when milk was treated with both homogenization and heating.

Effect of different heat treatments on the strong binding interactions between whey proteins and milk fat globules in whole milk

1996 ◽  
Vol 63 (3) ◽  
pp. 441-449 ◽  
Author(s):  
Milena Corredig ◽  
Douglas G. Dalgleish
Keyword(s):  
Milk Fat ◽  
Whey Proteins ◽  
Surface Load ◽  
Steam Heating ◽  
Fat Globules ◽  
Whole Milk ◽  
Milk Fat Globules ◽  
Fat Globule ◽  
Milk Fat Globule Membranes ◽  
Β Lactoglobulin

SummaryThe heat-induced binding of whey proteins to milk fat globule membranes in whole milk was investigated by quantitative electrophoresis and laser scanning densitometry. Both α-lactalbumin and β-lactoglobulin bound to the surfaces of fat globules when milk was heated in a water bath in the temperature range 65–85 °C. The interaction behaviour of α-lactalbumin did not seem to change with temperature, and the total amount of protein bound was ∼ 0·2 mg/g fat contained in the cream. The quantity of βlactoglobulin interacting with the milk fat globules increased with temperature from 02 to 0·7 mg/g fat between 65° and 85 °C. Even in whole milk heated at batch pasteurization temperatures (60–65 °C), α-lactalbumin and β-lactoglobulin were found attached to the fat globules. The interactions of the whey proteins with intact fat globule membranes were also investigated in milk heated in an industrial system (a pilot scale UHT and high temperature short time module), and the results were compared with those from the laboratory treatment (simple batch heating). The binding of the whey proteins to fat globules differed between milk heated by UHT using indirect steam heating or direct steam injection (DSI). However, the surface load in milk treated by DSI was not comparable to that of milk treated by batch heating or indirect steam heating, because of the changes in fat globule size and membrane composition caused by the DSI process.

A study of cow's milk containing high levels of linoleic acid: isolation and properties of the fat-globule membrane

1976 ◽  
Vol 43 (3) ◽  
pp. 389-400 ◽  
Author(s):  
R. W. Sleigh ◽  
Joan M. Bain ◽  
R. W. Burley
Keyword(s):  
Fatty Acid ◽  
Linoleic Acid ◽  
Unsaturated Fatty Acid ◽  
Milk Fat ◽  
High Speed ◽  
Lipid Membrane ◽  
Electrophoretic Pattern ◽  
Whole Milk ◽  
Fat Globule ◽  
Control Milk

SummaryProperties of whole milk and milk fractions from cows fed a diet that gave a greatly increased proportion of unsaturated fatty acid residues (especially of linoleic acid) in the milk lipids were studied, and this milk (high-linoleic milk) was compared with milk from cows on a control diet (control milk). The milk fractions were isolated by high-speed centrifugation of whole milk or cream and were examined by chemical analysis and electron microscopy. During centrifugation the globules of milk fat were disrupted and the membranes (fat-globule ‘ghosts’) floated as a layer beneath the free lipid. Membrane proteins from the 2 sorts of milk gave the same electrophoretic pattern and the amino acid compositions were the same. Lipid analysis of the membrane fraction from high-linoleic milk showed the expected increase in the proportion of unsaturated fatty acid residues in the neutral lipids, but there was an unexpected decrease in the proportion of unsaturated residues in the membrane phospholipids. No differences were found between high-linoleic and control milk in the ultrastructure of the milk-fat globules or the isolated membranes.

Interactions between the bovine milk fat globule membrane and skim milk components on heating whole milk

1992 ◽  
Vol 59 (2) ◽  
pp. 187-195 ◽  
Author(s):  
Avis V. Houlihan ◽  
Philippa A. Goddard ◽  
Stephen M. Nottingham ◽  
Barry J. Kitchen ◽  
Colin J. Masters
Keyword(s):  
Milk Fat ◽  
Bovine Milk ◽  
Skim Milk ◽  
Milk Proteins ◽  
Raw Milk ◽  
Membrane Lipid ◽  
Milk Fat Globule Membrane ◽  
Whole Milk ◽  
Milk Fat Globule ◽  
Fat Globule

SummaryHeating raw milk at 80 °C for 2·5–20 min was found to result in compositional changes in the milk fat globule membrane (MFGM). The yield of protein material increased with the duration of heating, owing to incorporation of skim milk proteins, predominantly β-lactoglobulin, into the membrane. Lipid components of the MFGM were also affected, with losses of triacylglycerols on heating.

scholarly journals Changes in structure of the bovine milk fat globule membrane on heating whole milk

1992 ◽  
Vol 59 (3) ◽  
pp. 321-329 ◽  
Author(s):  
Avis V. Houlihan ◽  
Philippa A. Goddard ◽  
Barry J. Kitchen ◽  
Colin J. Masters
Keyword(s):  
Milk Fat ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Skim Milk ◽  
Milk Proteins ◽  
Milk Fat Globule Membrane ◽  
Whole Milk ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Membrane Components

SummaryThe effects of heat-induced interactions between milk fat globule membrane components and skim milk proteins in whole milk on the structure of the membrane were examined by isopycnic sucrose density gradient centrifugation and by using Triton X-100 as a membrane probe. Skim milk components were incorporated into all the lipoprotein fractions separated by density gradient centrifugation. High density complexes, higher in density than those found in the natural milk fat globule membrane, were formed during the heat treatment. Losses of natural membrane polypeptides from the medium and low density lipoproteins were observed on heating. Heating whole milk also altered the rate of release of membrane components by detergent, with decreases in protein released and an increase in phospholipid constituents released. Studies on washed cream indicated that some of the changes in the membrane on heating whole milk occurred due to the heat treatment alone, independent of the interactions with skim milk proteins.

Glycosphingolipids from bovine milk and milk fat globule membranes: a comparative study. Adhesion to enterotoxigenic Escherichia coli strains

2009 ◽  
Vol 390 (1) ◽  
Author(s):  
Fernando Sánchez-Juanes ◽  
Josefa M. Alonso ◽  
Lorena Zancada ◽  
Pablo Hueso
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Milk Fat ◽  
Fatty Acid Content ◽  
Fat Globules ◽  
Whole Milk ◽  
Milk Fat Globules ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes

AbstractSeveral components of milk fat globule membranes (MFGMs) have been reported to display beneficial health properties and some of them have been implicated in the defense of newborns against pathogens. These observations prompted us to determine the glycosphingolipid content of MFGMs and their interaction with pathogens. A comparative study with whole milk components was also carried out. Milk fat globules and MFGMs were isolated from milk. Gangliosides and neutral glycosphingolipids were obtained from MFGMs and whole milk and their fatty acid contents were determined by gas chromatography-mass spectrometry (GC-MS). MFGMs and whole milk showed similar ganglioside and neutral glycosphingolipid contents, with whole milk having more GM3 and glucosylceramide and less GD3,O-acetyl GD3,O-acetyl GT3, and lactosylceramide. The fatty acid content of gangliosides from both sources showed a similar composition. However, the neutral glycosphingolipid fatty acid content seemed to be quite different. Whole milk had fewer very-long-chain fatty acids (18.1% vs. 46.4% in MFGMs) and more medium-chain and unsaturated C18:1 and C18:2 fatty acids. Milk fat globules, MFGMs, lactosylceramide, and gangliosides GM3 and GD3 were observed to bind enterotoxigenicEscherichia colistrains. Furthermore, bacterial hemagglutination was inhibited by MFGMs and glycosphingolipids.

A major prolactin-binding complex on human milk fat globule membranes contains cyclophilins A and B: the complex is not the prolactin receptor

2012 ◽  
Vol 302 (5) ◽  
pp. E585-E594
Author(s):  
Mary Y. Lorenson ◽  
Eric K. Ueda ◽  
KuanHui E. Chen ◽  
Ameae M. Walker
Keyword(s):  
Complex Formation ◽  
Human Milk ◽  
Milk Fat ◽  
Prolactin Receptor ◽  
High Capacity ◽  
Placental Lactogen ◽  
Whole Milk ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes

Prolactin (PRL) in milk influences maturation of gastrointestinal epithelium and development of both the hypothalamo-pituitary and immune systems of offspring. Here, we demonstrate that most PRL in human milk is part of a novel, high-affinity, multicomponent binding complex found on the milk fat globule membrane and not in whey. To examine properties of the complex, a sensitive ELISA was developed such that human PRL (hPRL) binding to the complex was measured by loss of hPRL detectability; thus, as much as 50 ng of hPRL was undetectable in the presence of 10 μl of human milk. Using the same methodology, no comparable complex formation was observed with human serum or amniotic fluid. hPRL complexation in milk was rapid, time dependent, and cooperative. Antibodies to or competitors of the hPRL receptor (placental lactogen and growth hormone) showed the hPRL receptor was not involved in the complex. However, hPRL complexation was antagonized by cyclosporine A and anti-cyclophilins. The complex was very stable, resisting dissociation in SDS, urea, and dithiothreitol. Western analysis revealed an ∼75-kDa complex that included hPRL, cyclophilins A and B, and a 16-kDa cyclophilin A. Compared with noncomplexed hPRL, complexed hPRL in whole milk showed similar activation of STAT5 but markedly delayed activation of ERK. Alteration of signaling suggests that complex formation may alter hPRL biological activity. This is the first report of a unique, multicomponent, high-capacity milk fat reservoir of hPRL; all other analyses of milk PRL have utilized defatted milk.

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