Supercritical CO2 Impregnation of Clove Extract in Polycarbonate: Effects of Operational Conditions on the Loading and Composition

The development of active packaging for food storage containers is possible through impregnation of natural extracts by supercritical CO2-assisted impregnation processes. The challenge of scCO(2)-impregnation of natural extracts is to control the total loading and to ensure that the composition of the loaded extract may preserve the properties of the crude extract. This study aimed at investigating the scCO(2)-impregnation of clove extract (CE) in polycarbonate (PC) to develop antibacterial packaging. A design of experiments was applied to evaluate the influences of temperature (35-60 degrees C) and pressure (10-30 MPa) on the clove loading (CL%) and on the composition of the loaded extract. The CL% ranged from 6.8 to 18.5%, and the highest CL% was reached at 60 degrees C and 10 MPa. The composition of the impregnated extract was dependent on the impregnation conditions, and it differed from the crude extract, being richer in eugenol (81.31-86.28% compared to 70.06 in the crude extract). Differential scanning calorimetry showed a high plasticizing effect of CE on PC, and high CL% led to the cracking of the PC surface. Due to the high loading of eugenol, which is responsible for the antibacterial properties of the CE, the impregnated PC is promising for producing antibacterial food containers.