Structure, diffusion, and permeability of protein-stabilized monodispersed oil in water emulsions and their gels: a self-diffusion NMR study.
Self-diffusion NMR is used to investigate monodispersed oil in water emulsions and the subsequent gel formed by removing the water through evaporation. The radius of the oil droplets in the emulsions is measured using a number of diffusion methods based on the measurement of the mean squared displacement of the oil, water, and tracer molecules. The results are consistent with the known size of the emulsions. Bragg-like reflections due to the restricted diffusion of the water around the oil droplets are observed due to the low polydispersity of the emulsions and the dense packing. The resulting data are fitted to a pore glass model to give the diameter of both the pools of interstitial water and the oil droplets. In the gel, information on the residual three-dimensional structure is obtained using the short time behavior of the effective diffusion coefficient to give the surface to volume ratio of the residual protein network structure. The values for the surface to volume ratio are found to be consistent with the expected increase of the surface area of monodisperse droplets forming a gel network. At long diffusion observation times, the permeability of the network structure is investigated by diffusion NMR to give a complete picture of the colloidal system considered.
Romoscanu
Alexandre I
AI
Nestle Research Centre, NESTEC LTD, 1000 Lausanne 26, Switzerland.
Fenollosa
Annia
A
Acquistapace
Simone
S
Gunes
Deniz
D
Martins-Deuchande
Teresa
T
Clausen
Pascal
P
Mezzenga
Raffaele
R
Nydén
Magnus
M
Zick
Klaus
K
Hughes
Eric
E
D004058:Diffusion; D004655:Emulsions; D005782:Gels; D007782:Lactoglobulins / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D044085:Microfluidics; D008853:Microscopy; D009821:Oils / Q000737:chemistry*; D010316:Particle Size; D010539:Permeability; D016062:Porosity; D011506:Proteins / Q000737:chemistry*; D013997:Time Factors; D014867:Water / Q000737:chemistry*
D004655:Emulsions; D005782:Gels; D007782:Lactoglobulins; D009821:Oils; D011506:Proteins; D014867:Water