INVESTIGADORES
PEREZ Oscar Edgardo
congresos y reuniones científicas
Título:
Competitive adsorption between surface-active polysaccharides and proteins: surface pressure and film rheology behavior
Autor/es:
PÉREZ, OSCAR E; MARTÍNEZ, KARINA D; MARTÍNEZ, MARÍA JULIA; CARRERA-SÁNCHEZ, CECILIO; PIZONES-RUÍZ HENESTROSA, VÍCTOR; RODRÍGUEZ-PATINO, JUAN M; PILOSOF, ANA MR.
Lugar:
Le Mans, Francia
Reunión:
Congreso; Food Colloids 2008, Polymeres, Colloids and Interfaces; 2008
Institución organizadora:
Universite du Maine
Resumen:
The interactions between
proteins and polysaccharides at the air-water interface are of great importance
for the formation and stability of food colloids as well as for the design of
interfacial films with specific properties. One distinctly group
of surface-active polysaccharides are the esters of alginic acid, propylene
glycol alginate (PGA). Hidroxypropylmethylcellulose
(HPMC) is a cellulose derivative which has methyl and hydroxypropyl groups
added to the anhydroglucose backbone. HPMC is of special interest for
controlled-release matrices. Methyl substitutes constitute
hydrophobic zones along the cellulose backbone whereas hydroxypropyl groups are
more hydrophilic. The introduction of these hydrophobic groups allows HPMC to
behave as a surfactant. Due to their surface-active character, competitive
adsorption could occur in mixtures of these polysaccharides and proteins. In this work we review the
interfacial behavior of the following mixed protein + polysaccharide systems:
β-lactoglobulin (βlg) + PGA, caseinomacropeptide (CMP) + PGA, whey protein
concentrate (80% protein)(WPC) + HPMC, soy protein isolate (SP) + HPMC in order
to understand how the surface active characteristics of each component and
their film forming abilities impact the properties of the mixed films.
Time-dependent surface
pressure and surface dilatational properties of single and mixed systems at
protein or polysaccharide bulk concentrations that allows monolayer saturation
were determined in an automatic drop tensiometer IT Concept at 20°C and pH 7. At this pH the
electrostatic complexation between proteins and polysaccharides is mainly
prevented.
The surface pressure over time
for HPMC mixtures with WPC or SP, showed a competitive behavior, dominated by HPMC because of
its unusual strong surface-activity. The surface dilatational modulus (Ed)
of mixed films at short adsorption times was dominated by the component that
adsorbed more rapidly. At long adsorption times, film rheology was dominated by
the component with the strongest Ed or lowest phase angle, WPC in the mixture
WPC + HPMC and HPMC in the mixture SP + HPMC.
The surface pressure over time for mixtures of a weak surface-active
polysaccharide as PGA with proteins (βlg or CMP) was dominated by βlg but
showed an intermediate value between single components for CMP, in spite of
being CMP much more surface-active than βlg.
blg also determined the rheological
properties of the mixed film because it
formed films with much better surface dilatational properties than PGA. In the
case of CMP + PGA mixture, where
both components had similar Ed, it was
observed that the relative viscoelasticity of the mixed film was lower
than that of single components indicating an antagonic effect.
It can be concluded that during competitive
adsorption between polysaccharides and proteins at high bulk concentrations,
the surface pressure would be dominated by the component that exhibits the
highest surface activity if this component also forms films with a high surface
dilatational modulus. The film rheology would be mainly dominated by the
biopolymer that can form the strongest viscoelastic films, but antagonic
interactions at the surface may alter this behavior.