INVESTIGADORES
PEREZ Oscar Edgardo
congresos y reuniones científicas
Título:
Adsorption kinetic and film rheology of whey proteins and hydroxypropylmethycellulose mixtures at the air-water interface.
Autor/es:
PEREZ, OSCAR E.; CARRERA-SÁNCHEZ, CECILIO; RODRÍGUEZ-PATINO, JUAN M; PILOSOF, ANA MR.
Lugar:
Montreux
Reunión:
Congreso; Food Colloids. Self Assembly and Material Science.; 2006
Institución organizadora:
The Nestlé Researh Center Lausanne Department of Food Science. The University of Fribourg Department of Physics
Resumen:
Whey proteins have many technological applications.
The main proteins present are lactoglobulin, o-lactalbumin and bovine
sero-albumin ami are responsible for the hydration capacity, gelling, foaming
and emulsi1ing properties of whey protein concentrates (WPC).
Hydroxypropylmethylcellulose (HPMC), which has methyl and hydroxypropyl groups
added at the anhydroglucose backbone, includes a family of cellulose ethers
that mainly differ in the molecular weight, viscosity, degree and molar
substitution. HPMC is used in the food industry, printing technology, and
pharmaceutical applications , in particular
for controlled drug-release. The usefulness of HPMC is essentially based upon
four key attributes: efficient thickening, surface activity, film forming
ability, and the capacity to form thermal geis that melt upon cooling.
The interactions between proteins and polysaccharides at the air-water
interface are of great importance for the formation and stability of food
colloid systems. Along-side the use of I{PMC as thickener to retard
destabilization of foams and emulsions, because of its surface activity it
would compete with proteins for the interfaces, affecting film properties and
stability.
In this work we studied the dynamic behavior of WPC + HPMC mixtures
at the air-water interface. Three different HPMC, so-called E4M, ESOLV and F4M
that exhibited different interfacial properties were used. Time-dependent
surface pressure and surface dilatational properties of single and mixeci
systems at different bulk concentrations were determined in an automatic drop
tensiometer IT Concept at 20±0.2
°C.
The results show that the surface-active HPMCs show a competitive behaviour
with WPC, that is modulated by the relative bulk concentration and time of
adsorption. At WPC concentrations where the protein can saturate the interface
(i.e. 1 %wt) WPC dominates the surface pressure and dilatational properties of
films at long adsorption times. Nevertheless, HPMC dominates the surface at
short adsorption time.
At lower WPC concentrations (0.01 % wt) the degree of competition depends on the
amount of FIPMC in the mixture. At low WPC and FIPMC concentrations, where none
of the macromolecules is able to saturate the interface, an additive or
synergistic surface pressure evolution is observed. However the surface
dilatational modulus of mixed films is greatly decreased in comparison to films
from single components, indicating that HPMC hinders the protein interfacial
aggregation.