*3.3. WVP*

The key factor in evaluating the feasibility of composite materials in food preservation is to determine the WVP value of composites. During food preservation, edible or biodegradable film can be used to reduce the transfer of moisture from the environment to the inside of the package [29]. The WVP values of neat SA film, as well as the SA nanocomposite film, are shown in Table 2. The WVP value of SA film is 38.2 × 10−<sup>2</sup> g mm/h KPa m2. The barrier of SA composite film to water vapor was significantly enhanced after incorporation of CIN or T-HNTs. When CIN was immobilized on T-HNTs and then incorporated into SA matrix, the WVP value of SA/T-HNTs-CIN film was reduced by 14.7% compared with that of SA film. There are many factors that affect the barrier properties of the film, such as the hydrophobicity, the structure, and the compatibility of the material. CIN is inherently hydrophobic, and its addition might increase the hydrophobic/hydrophilic ratio of the film [30]. As a high aspect ratio aluminosilicate mineral, HNTs have barrier properties to water vapor. HNTs dispersed in the matrix might make the path of water molecules through the matrix become tortuous [10]. All of these might be the reasons for the decrease of WVP value of the film. Yousefi et al. added halloysite nanotubes and *Origanum vulgare* essential oil to the film matrix, which also improved the water resistance of the film [29].

**Table 2.** Water vapor permeability of SA-based composite film.


Data are presented as mean ± standard deviation and different letters (a, b) within the columns shows the significant differences (*p* < 0.05), where a is the lowest value.
