RESULTS & DISCUSSION
Previous studies [1, 2], have shown that lecithin or caseinate can be used as anionic compounds
to form chitosan nanoparticles, with chitosan forming the outer layer and the anionic
compound in the particle core. Figure 1(a) shows the particle sizes measured for the different
systems. Particle sizes ranged from 50 to 200 nm and were dependent on the compound
(lecithin or caseinate), the processing condition and the presence of the surfactant Tween 20.
Figure 1(b), shows the zeta potential of the particles. Even though zeta potential values of both
chitosan-lecithin and chitosan-caseinate samples were +28 and +17 mV respectively, almost all
samples showed to be stable after the 20-day storage with no differences on their size observed
within the evaluated period. The exception were the samples processed only with the Turrax
device with no addition of surfactant, in which an increase of 50% on particle size was
observed after storage. This indicates that the shearing effect promoted by the rotor-stator
device by itself was not sufficient to promote system stabilization. In this case, either
aggregates may have formed or the core/shell structure may have “opened”, enhancing the
measured hydrodynamic diameter during storage.