Roeland Rombaut

Effect of washing conditions on the recovery of milk fat globule membrane proteins during the isolation of milk fat globule membrane from milk

During the isolation of milk fat globule membrane (MFGM) from milk, washing is considered the most critical stage in which loss of MFGM components occurs. In this study, using a cream separator, the influence of washing on the recovery of MFGM proteins was investigated. The residue of non-MFGM proteins in the MFGM material obtained after washing was quantitatively determined using densitometric analysis of one-dimensional sodium dodecyl sulfate-PAGE after silver staining of the gel. Using deionized water as the washing solution did not increase the loss of MFGM proteins compared with other common salt solutions in terms of recovery of MFGM proteins and contamination with non-MFGM proteins. The increase in wash temperature from 38 to 46 degrees C did not show a significant decrease in yield of MFGM proteins because of variation between the experimental replicates. Coalescence of fat globules occurs during isolation. To increase MFGM purity while maintaining a high MFGM protein recovery, using larger volumes of wash solution is more advisable rather than increasing the number of washings from 2 to 3.

Improved solvent extraction procedure and high-performance liquid chromatography-evaporative light-scattering detector method for analysis of polar lipids from dairy materials

A normal-phase high-performance liquid chromatography-evaporative light-scattering detector method employing dichloromethane, methanol, and acetic acid/triethylamine buffer as the mobile phase was developed for analysis of polar lipids (PLs). This method was applicable for analysis of PLs from both dairy materials and soy lecithin. All of the PLs of interest such as glycolipids, phospholipids, and sphingomyelin were well separated with a total run time of 22.5 min and without necessitating the removal of neutral lipids beforehand. Peak retention times were stable, and the method was reproducible. In this study, a modified method of using solvents for extraction of PLs from dairy matrices was also investigated. The modified method offered higher extraction efficiency, consumed less time, and in some cases saved solvent use.