Size distribution of pressure-decomposed casein micelles studied by dynamic light scattering and AFM.
Reversible and irreversible states of pressure-dissociated casein micelles were studied by in situ light scattering techniques and ex situ atomic force microscopy. AFM experiments performed at ambient pressure reveal heterogeneities across the micelle, suggesting a sub-structure on a 20 nm scale. At pressures between 50 and 250 MPa, the native micelles disintegrate into small fragments on the scale of the observed sub-structure. At pressures above 300 MPa the micelles fully decompose into their monomeric constituents. After pressure release two discrete populations of casein aggregates are observed, depending on the applied initial pressure: Between 160 and 240 MPa stable micelles with diameters near 100 nm without detectable sub-structures are formed. Casein micelles exposed to pressures above 280 MPa re-associate at ambient pressure yielding mini-micelles with diameters near 25 nm. The implications concerning structural models are discussed.
Gebhardt
Ronald
R
Physik-Department E 13, Technische Universität München, 85748, Garching, Germany.
Doster
Wolfgang
W
Friedrich
Josef
J
Kulozik
Ulrich
U
D055592:Biophysical Phenomena; D001703:Biophysics; D002364:Caseins / Q000737:chemistry*; D008027:Light; D008823:Micelles; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D011312:Pressure; D012542:Scattering, Radiation
D002364:Caseins; D008823:Micelles