able, since they had a small size and thus well integrated into thepolymer matrix. The small particle size led to increased interac-tions between the polymer matrix and essential oil, which led to aless cohesive composite matrix and hardly traceable oil droplets(Bonilla et al., 2012). In contrast, in biocomposite film contain-ing higher OEO content (i.e. 0.8–1.2% w/v), the oil droplets werelarge enough to be visible (Fig. 3c and d). This might be describedby the fact that in the oil-in-water emulsions, the collision fre-quency between the droplets increases with a higher lipid content,which consecutively increases flocculation and coalescence rate(McClements, 2005). Similar results were observed by Sánchez-González et al. (2009) when tea tree essential oil was added to theHPMC film. It was postulated that the film microstructure couldbe related with the reduction in tensile strength and higher watervapor permeability of films added with oregano essential oils, com-pared with native film.