High-pressure-induced interactions between milk fat globule membrane proteins and skim milk proteins in whole milk.
The association of beta-lactoglobulin (beta-LG) and alpha-lactalbumin (alpha-LA) with milk fat globule membrane (MFGM), when whole milk was treated by high pressure in the range 100 to 800 MPa, was investigated using sodium dodecyl sulfate (SDS)-PAGE under reducing and nonreducing conditions. In SDS-PAGE under reducing conditions, beta-LG was observed in the MFGM material isolated from milk treated at 100 to 800 MPa for 30 min, and small amounts of alpha-LA and kappa-casein were also observed at pressures >600 MPa for 30 min. However, these proteins were not observed in SDS-PAGE under nonreducing conditions. These results indicate that beta-LG and alpha-LA associated with MFGM proteins via disulfide bonds during the high-pressure treatment of whole milk. The amount of beta-LG associated with the MFGM increased with an increase in pressure up to 800 MPa and with increasing time of pressure treatment. The maximum value for beta-LG association with the MFGM was approximately 0.75 mg/g of fat. Of the major original MFGM proteins, no change in butyrophilin was observed during the high-pressure treatment of whole milk, whereas xanthine oxidase was reduced to some extent beyond 400 MPa. In contrast to the behavior during heat treatment, PAS 6 and PAS 7 were stable during high-pressure treatment, and they remained associated with the MFGM.
Ye
A
A
Riddet Centre, Massey University, Palmerston North, New Zealand.
Anema
S G
SG
Singh
H
H
D000818:Animals; D004220:Disulfides / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D005223:Fats / Q000032:analysis / Q000737:chemistry; D005519:Food Preservation / Q000379:methods; D006017:Glycolipids / Q000032:analysis / Q000737:chemistry*; D006023:Glycoproteins / Q000032:analysis / Q000737:chemistry*; D006358:Hot Temperature; D007782:Lactoglobulins; D066292:Lipid Droplets; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis / Q000737:chemistry*; D011312:Pressure
D004220:Disulfides; D005223:Fats; D006017:Glycolipids; D006023:Glycoproteins; D007782:Lactoglobulins; D008562:Membrane Glycoproteins; D008894:Milk Proteins; C110367:milk fat globule