pH- and ionic strength-dependent interaction between cyanidin-3-O-glucoside and sodium caseinate
Résumé
Understanding the mechanism of interaction between food proteins and bioactives constitutes the preliminary
step to design food grade nanocarriers. We investigated the interaction between cyanidin-3-
O-glucoside (C3G), and 20 nm-sized sodium caseinate nanoparticles (NaCas) at pH 7 and pH 2 by
fluorescence spectroscopy and dynamic light scattering. The characterization of the C3G-NaCas interaction
indicated that the fluorescence quenching mechanism was predominantly static. C3G interacted
with two sets of binding sites with association constants Ka of 106 and 105 M 1. Electrostatic interactions
dominated at pH 7, while hydrophobic effects were the main force at pH 2. Interestingly, the two sets of
binding sites were discriminated by ionic strength at pH 7. The binding of C3G slightly modified the
average diameter of NaCas nanoparticles without alteration of its surface charge suggesting a complexation
of C3G molecules in the internal casein structure. Thus, NaCas constitutes a putative nanocarrier for
anthocyanins in new functional foods.
