INTECIN   20395
INSTITUTO DE TECNOLOGIAS Y CIENCIAS DE LA INGENIERIA "HILARIO FERNANDEZ LONG"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
CHARACTERIZATION OF WHEY PROTEIN-POLYPHENOL INTERACTIONS BY DYNAMIC LIGHT SCATTERING
Autor/es:
M. VON STASZEWSKI, R.J. JAGUS AND A.M.R. PILOSOF
Reunión:
Congreso; International Congress on Engineering and Food (ICEF 11).; 2011
Resumen:
n
the past few decades, many drinkable dairy products added with green
tea polyphenols have been launched by food industries because
epidemiological studies suggest an association between the prevention
of diseases and the consumption of polyphenol-rich beverages or foods.
However, polyphenols have a significant affinity for proteins that
leads to formation of soluble complexes, which can grow in size and
even form sediments. The destabilization of the system will depend on pH, the nature of both the protein and the polyphenol and their relative concentrations.
The aim of this work was to study the binding of green tea polyphenols to b-lactoglobulin, caseinomacropeptide and a-lactalbumin in a pH range between 3.0 and 6.0 by means of dynamic light scattering.
Whey
proteins and polyphenol aqueous solutions were prepared in citrate
buffer (pH 3.0, 0.01M), acetate buffer (pH 4.5, 0.01M) or phosphate
buffer (pH 6.0, 0.01M) and filtered through 0.45, 0.22 and 0.02 mm
microfilters (Whatman International Ltd., England). Dynamic light
scattering experiments were carried out in a Dynamic Laser Light
Scattering (DLS) (Zetasizer Nano-Zs, Malvern Instruments, Worcestershire, United Kingdom)
provided with a HeNe laser (633 nm) and a digital correlator, Model
ZEN3600. Measurements were carried out at a fixed scattering angle of
173º. The assay was carried out in triplicate.
The
intensity size distributions for all the samples were monomodal and
the peaks shifted to higher sizes as compared to pure proteins. It
is noticeable that the particle size measured by light scattering
changed with pH. Close to the isoelectric point of each protein the
aggregation potential of polyphenols and the size of the complexes
formed were the highest. Although the initial binding of
polyphenols to whey proteins is essentially a non-selective
hydrophobically driven interaction, the insolubility of the complex
formed is most likely determined by surface charge effects. At the
isoelectric point of the proteins, complexation proceeds up to form big
particles that can easily precipitate.
Controlling
the interactions between whey proteins and green tea polyphenols would
therefore provide a tool to improve the development new functional
foods.