Polylactic acid-based materials encapsulating carvacrol obtained by solvent casting and electrospinning.

Polylactic acid (PLA) dissolved (15 wt.%) in ethyl acetate (EtAc): dimethyl sulfoxide (DMSO) binary systems (0:1; 1:3, and 2:3 v/v) was used as carrier to obtain carvacrol (CA)-loaded (20 wt.% with respect to PLA) matrices by electrospinning, in comparison with solvent casting. Field emission scanning electron microscopy (FESEM) observations showed that CA-loaded electrospun fibers were thinner than the CA-free ones, and their encapsulating efficiency (EE) increased when EtAc was present in the solvent. The cast films had higher EE (up to 89%) than the electrospun mats (maximum 68%). Thermogravimetric analysis and differential scanning calorimetry revealed that CA-free matrices retain more solvent than the samples with CA; this effect is being more noticeable in fibers rather than in cast films. The thermal analysis revealed stronger retention forces of CA in the fibers than in the cast material and the CA plasticizing effect in the PLA matrices, in accordance with its retained amount. PRACTICAL APPLICATION: The carvacrol-loaded polylactic acid materials obtained in this study are intended to serve as possible active layer in obtaining active (antimicrobial and/or antioxidant) multilayer materials for the packaging of foodstuffs, when applied onto a supporting polymer layer. Active properties of the material, as well as the potential carvacrol sensory impact, in packaged products should be assessed in further studies.