Supercritical Carbon Dioxide-Based Techniques

New evidence shows that the development of active packaging films is augmented by supercritical carbon dioxide (SC−CO2) impregnation [8]. The observations made by Franco et al. [8] were collaborated by Lukic et al. [9] and Trucilo et al. [10], who documented

the development of active food packaging products made of PLA/PCL combined with thymol and/or carvacrol and liposomes. The antioxidant and packaging properties of the active packaging materials were augmented by supercritical carbon dioxide (SC-CO2) impregnation [9]. The choice of the supercritical CO<sup>2</sup> is grounded in its ability to yield good material properties based on its near-zero surface tension, low viscosity, and high diffusion coefficient [10]. The suitable material properties partly explain why SC-CO<sup>2</sup> has been extensively applied in membrane formation, desorption, micronization, and extraction. However, in contrast to Franco et al. [8], Lukic et al. [9], Trucilo et al. [10], Ozkan et al. [11] and Cejudo et al. [12] have argued that the utility of SC-CO<sup>2</sup> in active packaging films was dependent on the role of the material (co-solvent, anti-solvent, or swelling agent). On the one hand, SC-CO<sup>2</sup> can function as a supercritical anti-solvent (this is critical in micronization or co-precipitation processes). On the other hand, it can function as a solvent or co-solvent. Following the appraisal of the two techniques, it was clear that the SC-CO<sup>2</sup> supercritical anti-solvent process (SAS) is highly appropriate in packaging given it yields products with customized properties such as spherical nanoparticles, and nanostructured filaments with controlled mean size and particle size distribution.
