The incorporation of cellulose nanocrystals in the chitosan matrix was observed to decrease water vapor permeability values, for example, from 3.31 to 2.23 gm/m2 day kPa, with 10 wt.% loading of CNC.36 The protection against oxidation of food or meat products can be reduced by packaging films with reduced oxygen perme­ability. The significant reduction in oxygen permeability was demonstrated with nanocomposite films prepared via layer by layer assembly by alternatively dipping in chitosan solution and CNC dispersion.43 The reduction in oxygen permeability of 180 mm thick A-PET substrate was about 94%, after 30 numbers of bilayers coating of chitosan and CNC via LBL assembly (Fig. 16.5).