Ye A, Anema S G, Singh H
Riddet Centre, Massey University, Palmerston North, New Zealand.
J Dairy Sci. 2004 Dec;87(12):4013-22. doi: 10.3168/jds.S0022-0302(04)73542-0.
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.
在100至800MPa范围内对全脂牛奶进行高压处理时，利用十二烷基硫酸钠（SDS）-聚丙烯酰胺凝胶电泳（PAGE）在还原和非还原条件下，研究了β-乳球蛋白（β-LG）和α-乳白蛋白（α-LA）与乳脂肪球膜（MFGM）的关联。在还原条件下的SDS-PAGE中，在100至800MPa处理30分钟的牛奶中分离出的MFGM物质中观察到了β-LG，并且在压力>600MPa处理30分钟时也观察到了少量的α-LA和κ-酪蛋白。然而，在非还原条件下的SDS-PAGE中未观察到这些蛋白质。这些结果表明，在全脂牛奶高压处理过程中，β-LG和α-LA通过二硫键与MFGM蛋白质相关联。与MFGM相关联的β-LG的量随着压力增加至800MPa以及压力处理时间的增加而增加。β-LG与MFGM关联的最大值约为0.75mg/g脂肪。在全脂牛奶高压处理过程中，主要的原始MFGM蛋白质中，未观察到嗜乳脂蛋白有变化，而黄嘌呤氧化酶在超过400MPa时有所减少。与热处理过程中的行为相反，PAS 6和PAS 7在高压处理过程中是稳定的，并且它们仍然与MFGM相关联。
