Supercritical impregnation and kinetic release of 2-nonanone in LLDPE films used for active food packaging

•LLDPE films were impregnated with 2-nonanone using supercritical CO2.•Impregnated films were characterized through DSC, FTIR–ATR and release tests.•Depressurization rate affects the amount of impregnated 2-nonanone.•The diffusion coefficient of 2-nonanone in LLDPE depends on depressurization rates.

The impregnation of active compounds in polymeric matrices using supercritical carbon dioxide (scCO2) is a well-known technique, which is currently used to formulate controlled drug release materials. In this study, supercritical impregnation of 2-nonanone in linear low-density polyethylene (LLDPE) was done in order to prepare active polymer films to be used in food packaging. Impregnation tests were carried out in a high-pressure cell, at 313 K with pressures ranging from 12 to 22 MPa and at two different depressurization rates: 1.0 and 10.0 MPa min−1. This procedure allowed the preparation of films containing 2-nonanone at concentrations varying from 0.21 to 0.34 w/w%.Higher concentrations of 2-nonanone in LLDPE were obtained for impregnations done at lower pressures and the lowest depressurization rate. Release experiments showed that the depressurization rate of the impregnation process is a key parameter, which significantly affects the initial content of the active compound in the polymer. Simultaneously, a phenomenological mass transfer model has been used to describe the release of 2-nonanone from the polymer to a food simulant. This model was used to correlate the experimental release kinetic data, obtaining the values of diffusion coefficient of 2-nonanone in LLDPE, which were quantified between 3.0 × 10−12 and 3.6 × 10−12 m2 s−1 when depressurization rate was 10.0 MPa min−1 and 6.8 × 10−12 m2 s−1 when its value was 1.0 MPa min−1.

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