Manufacture of β-chitin nano- and microparticles from jumbo squid pen (Dosidicus gigas) and evaluation of their effect on mechanical properties and water vapour permeability of polyvinyl alcohol/chitosan films

Polyvinyl alcohol/chitosan (PVA/CS) films, which may be a good alternative for food packaging, have a limited vapour water barrier. This study investigated, the effect of β-chitin micro- and nanoparticles (MPs and NPs, respectively) obtained from jumbo squid (Dosidicus gigas) pens on the water vapour permeability (WVP) of PVA/CS films. By milling β-chitin, squid MPs (sizes of 128 μm; MpQ128) were obtained, and an aqueous acid dispersion of MpQ128 was ultrasonicated to obtain NPs. Besides, PVA/CS films with three different proportions were prepared. The addition of MpQ128 did not increase the thickness or tensile strength (TS) of these films. The percentage elongation (%E) of the film increased only in one of the PVA/CS film proportions. The addition of NPs in this PVA/CS film did not increase the film thickness; however, the TS and %E increased significantly compared to those of the control sample, and the increase in %E was significantly higher with NPs than with MPs.Moreover, the PVA film exhibited biphasic water loss kinetics, and the film showed three-phase behaviour for various CS amounts. The WVP values did not significantly change for different PVA/CS proportions during each experimental period. However, in the second period, the WVP was significantly lower than in the first and third periods. The addition of MPs or NPs did not significantly decrease the WVP compared to that of the control sample. Nevertheless, it decreased slightly for some NP additions in the films. The effectiveness of β-chitin NPs in reducing the WVP can be improved by avoiding the aggregation of NPs in hydrophilic PVA/CS films.