Supercritical CO2-impregnation of clove extract in PLLA films: Assessing process parameter effects on extract loading and composition

The supercritical carbon dioxide (scCO2) impregnation of clove extract (CE) into poly(L-lactic acid) (PLLA) films was explored with varying pressure (10-30 MPa) and temperature (35-60 degrees C), achieving high clove extract loadings (CL) (12.3 - 44.4%). In all conditions, impregnated extracts exhibited elevated eugenol content and reduced content of eugenyl acetate, beta-caryophyllene, and alpha-humulene, compared to crude extract, showing the selective character of the process. Strong eugenol/PLLA affinity demonstrated by solubility parameters and hydrogen bonds permitted its effective impregnation. Eugenol significantly plasticized PLLA film, resulting in alterations in its microstructure, including increased crystallinity and smaller crystals. A CL of 23.8% maintained a dense and uniform structure of PLLA, while 44.4% induced a thick microporous layer on the surfaces. CEimpregnated PLLA, rich in eugenol, is promising for developing active food packaging and extract-releasing medical.