Kappa-casein micelles: structure, interaction and gelling studied by small-angle neutron scattering.
Small-angle neutron scattering (SANS) measurements on dilute and concentrated dispersions of kappa-casein micelles in a buffer at pH = 6.7 were made using the D11 diffractometer in Grenoble. Results indicate that the micelles have a dense core with a fluffy outer layer. This outer layer appears to give rise to a steeply repulsive interaction on contact. In fact, the hard-sphere model best fits the measured scattering intensities. Adding chymosin to the dispersion initiated a fractal flocculation of the micelles and consecutively a coalescence of the micelles. This unexpected second process resembled that of spinodal demixing. The dispersion phase thus separates into a water and a protein phase on a time scale of hours. The observed phenomona contribute to the understanding of the cheese-making process.
de Kruif
C G
CG
Netherlands Institute for Dairy Research, Ede.
May
R P
RP
D002364:Caseins / Q000737:chemistry*; D012085:Chymosin / Q000737:chemistry; D006020:Glycopeptides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008823:Micelles; D009502:Neutrons; D012542:Scattering, Radiation
D002364:Caseins; D006020:Glycopeptides; D008823:Micelles; C020251:kappa-casein glycomacropeptide; D012085:Chymosin