and decreasing. gLV was higher than 55 mJ m2 after 20 min. This
time evolution characterizes the kinetics of adsorption and recon-
figuration of chitosan at interface. The high surface tension of chitosan
coatings indicates that the forces between molecules of the
coating are very strong, leading to high contact angles (poor
wetting) on the blueberry epicarp. With the objective to increase
the wetting, a plasticizer like glycerol was used. Indeed, plasticizers
decrease the attractive intermolecular forces in the molecular
tridimensional organization, and increase the chain mobility. The
interfacial tension of glycerol/chitosan solution decreases more
rapidly than chitosan solution as presented in Fig. 4. To decrease the
water vapor permeability, Tween 20 was added to chitosan coating
solution, therefore the surface tension was diminished and time
independent (for example, only the concentration 1 g/100 g is
shown).
The cohesive energy (Eq. (15)), Wc, was calculated with a surface
tension corresponding to the CA equilibrium measurement time,
i.e., 3060 s presented in Fig. 4. In Fig. 5, Wc is plotted as function of