Transition from fractal to spherical aggregates of globular proteins: Brownian-like activation and/or hydrodynamic stress?
We report on the structure of whey protein aggregates formed by a short heating coupled to shear at high temperatures (80-120) and neutral pH in scale-up processing conditions, using gel filtration chromatography, light scattering, small angle neutron scattering, and cryogenic transmission electron microscopy. The results are interpreted in terms of coexistence of residual non-aggregated proteins and aggregates. The characteristics of aggregates such as the size, the aggregation number and the shape evidence two different morphologies. Whereas aggregates formed at 80 °C show a selfsimilar structure down to a length scale of the monomer with a fractal dimension typical for reaction limited cluster aggregation (D~2.2), aggregates formed at higher temperature show a spherical morphology, with the structure from small angle neutron scattering data best modelled with the form factor of a polydisperse sphere. We compare the structure of these aggregates to that of aggregates formed in quiescent conditions at lab scale. The structure transition is interpreted in terms of a non-trivial interplay between three perturbation factors: interparticle interaction, temperature and shear.
Najet
N
Mahmoudi
Cedric
C
Gaillard
Alain
A
Riaublanc
François
F
Boue
Physics Department, University of Fribourg, Chemin du Musée, 3, CH-1700, Fribourg, Switzerland. najet.mahmoudi@unifr.ch.
Monique A V
MA
Axelos
D017709:Fractals; D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D008894:Milk Proteins / Q000737:chemistry*; D017510:Protein Folding; D013696:Temperature; D000067816:Whey Proteins
D008894:Milk Proteins; D000067816:Whey Proteins