KINETICS OF ADSORPTION OF WHEY PROTEINS AND HYDROXYPROPYLMETHYLCELLULOSE MIXTURES AT THE AIR-WATER INTERFACE.

PÉREZ, OSCAR E; CARRERA-SÁNCHEZ, CECILIO; PILOSOF, ANA MR; RODRÍGUEZ-PATINO, JUAN M

JOURNAL OF COLLOID AND INTERFACE SCIENCE

ELSEVIER

Lugar: Amsterdam; Año: 2009 vol. 332 p. 485 - 496

0021-9797

The aim of this research is to quantify the competitive adsorption of a whey proteinconcentrate (WPC) and hydroxypropyl-methyl-cellulose (HPMC so called E4M, E50LV and F4M) at the air-water interface by means of dynamic surface tensiometry and Brewster angle microscopy (BAM). These biopolymers are often used together in many food applications.The concentration of both protein and HPMC, and the WPC/HPMC ratio in the aqueous bulkphase were variables, while pH (7), the ionic strength (0.05M) and temperature (20ºC) werekept constant. The differences observed between mixed systems were in accordance with therelative bulk concentration of these biopolymers (CHPMC and CWPC) and the molecularstructure of HPMC. At short adsorption times, the results show that under conditions where both WPC and HPMC could saturate the air-water interface on their own or when CHPMC CWPC, the polysaccharide dominates the surface. At concentrations where none of thebiopolymers was able to saturate the interface, a synergistic behavior was observed for HPMCwith lower surface activity (E50LV and F4M), while a competitive adsorption was observedfor E4M (the HPMC with the highest surface activity). At long-term adsorption the rate ofpenetration controls the adsorption of mixed components. The results reflect complexcompetitive/synergistic phenomena under conditions of thermodynamic compatibility or inthe presence of a “depletion mechanism”. Finally, the order in which the differentcomponents reach the interface will influence the surface composition and the film properties.