Phase separation, rheology and microstructure of micellar casein–guar gum mixtures

The properties of micellar casein+guar gum mixed systems have been investigated at 20°C, pH 7 and in 0.25 M NaCl; in these conditions, the mixtures tended to phase separate, probably due to depletion-flocculation mechanisms. Ternary phase diagrams have been established according to the biopolymer co...

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Bibliographic Details
Published in:Food hydrocolloids 1999, Vol.13 (1), p.43-49
Main Authors: Bourriot, Sophie, Garnier, Catherine, Doublier, Jean-Louis
Format: Article
Language:English
Subjects:
Biological and medical sciences
casein
Chemical Sciences
flocculation
flow
Food and Nutrition
Food engineering
Food industries
Fundamental and applied biological sciences. Psychology
General aspects
guar gum
Life Sciences
micelles
Miscellaneous
mixtures
Polymers
separation
shear
ultrastructure
viscoelasticity
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Summary:The properties of micellar casein+guar gum mixed systems have been investigated at 20°C, pH 7 and in 0.25 M NaCl; in these conditions, the mixtures tended to phase separate, probably due to depletion-flocculation mechanisms. Ternary phase diagrams have been established according to the biopolymer concentrations. The rheological properties of these mixed systems have been investigated in the monophasic domain, as well as in the biphasic one. Modifications of the flow and the viscoelastic properties with respect to the individual components were clearly evidenced in the two-phase domain. The ultrastructure of the guar gum-micellar casein mixtures has been described using confocal laser scanning microscopy. In the biphasic domain, observations of the mixed system at concentrations corresponding to those of rheological measurements clearly evidenced that the phase separation process has yielded a continuous network mostly composed of the aggregated micellar casein.
ISSN:0268-005X
1873-7137
DOI:10.1016/S0268-005X(98)00068-X