Stabilization of amylopectin-pullulan water in water emulsions by Interacting protein particles
Résumé
Water in water emulsions were prepared by mixing aqueous solutions of amylopectin (AMP) and pullulan (PUL) in the presence of whey protein microgels (MG). Attractive interaction between the MG was introduced by decreasing the pH from neutral towards their isoelectric pH either by adding HCl while stirring or progressively in-situ by adding glucono-delta-lactone (GDL). Decreasing the pH led to a change in the preference of the MG from the PUL phase to the AMP phase and to adsorption of the MG at the interface. The morphology of the emulsions was observed using confocal laser scanning microscopy. The morphology and stability of the emulsions depended strongly on the pH and differed when AMP droplets were dispersed in the PUL phase or vice versa. In some cases, stable weak emulsion gels were formed that flowed when tilted. In others, droplets remained dispersed in a liquid phase stabilized by a gelled interface layer of MG. The interaction between the MG was further modulated by adding small amounts of anionic polysaccharides that formed complexes with the MG below pH 5.6. This was found to influence the partitioning of the MG between the phases, as well as the stability and morphology of the emulsions.
Domaines
Ingénierie des aliments
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