*3.4. Barrier Properties: Water Vapor Permeability*

The barrier properties of the films, and particularly water permeability, plays a critical role in evaluating the practical applications of functional films. It was expected that the films with licorice EO presented lower water permeability since the hydrophobic nature of the EO was known to contribute to the decrease of WVP [22]. Furthermore, in the present work, the WVP was significantly higher (*p*-value < 0.05) in the zein films casted on lotus negative template, compared to the ones casted on simple polystyrene Petri dishes (Table 2). The WVP of the films casted on polystyrene is near 2.74 <sup>×</sup> <sup>10</sup>−<sup>6</sup> <sup>g</sup>/(Pa.day.m) while for the films casted on lotus negative template it is about 3–4 <sup>×</sup> <sup>10</sup>−<sup>6</sup> <sup>g</sup>/(Pa.day.m), indicating that the water barrier properties of the films were weakened. The support material where the films were casted seems to influence the WVP, probably because of the higher values of thickness obtained for the films casted on lotus negative template. The zein-based films developed in the present work presented strong water barrier properties than the ones obtained previously with chitosan-zein edible films incorporated with anise, orange and cinnamon essential oils (250 ppm) [31].


**Table 2.** Barrier properties of the films: water vapor permeability.

(Results expressed as mean ± SD) a, b, c and d correspond to each type of film; Significant *p*-values are highlighted in bold.
