Microfiltration of Butter Serum Upon Casein Micelle Destabilization

Contour plot of the L* value (a measure of casein micelle dissociation) of butter serum as a function of temperature and citrate concentration. The original L* value was 77.4 at 20°C.

Contour plot of the L* value (a measure of casein micelle dissociation) of butter serum as a function of temperature and alcohol concentration. Note that the latter is the concentration of ethanol in the water solution, which is mixed with the butter serum in a 1:1 ratio. The original L* value of a 1:1 water:butter serum mixture was 74.7 at 20°C.

Permeate flux during microfiltration of reconstituted butter serum (○) and reconstituted butter serum in the presence of 80mM sodium citrate (●). Temperature was kept at 50°C, the transmembrane pressure at 0.1MPa, and the feed velocity over the membrane at 2.14m/s.

Polar lipid profile of butter serum as obtained by HPLC-evaporative light-scattering detection (ELSD). NL=neutral lipids, GluCer=glucosylceramide, LacCer=lactosylceramide, PE=phosphatidylethanolamine, PI=phosphatidylinositol, PS=phosphatidylserine, PC=phosphatidylcholine, SM=sphingomyelin.

Sodium dodecyl sulfate-PAGE gel of the different fractions obtained from butter serum. Lane 1=molecular weight marker (kDa); lane 2=reconstituted butter serum; lane 3=milk fat globule membrane (MFGM) standard; lanes 4 and 5=microfiltration retentates of butter serum without and with citrate addition, respectively (vertical streaking in lane 4 is due to oversampling; as such, comparison with other lanes with respect to concentration should be done with some precaution); lanes 6 and 7=microfiltration permeates of butter serum without and with citrate addition, respectively. The naming of the major MFGM proteins has been done according to the review article of Mather (2000): ADPH=adipophilin; BTN=butyrophilin; CD36=cluster of differentiation 36; MUC1=mucin 1; PAS 6/7=periodic acid Schiff 6/7; and XO=xanthin oxidase/dehydrogenase. Observed whey proteins are BSA, α-LA, and β-LG. The 4 major caseins (CAS) were also detected.