Encapsulación de Carvacrol en nanofibras de PCL y su aplicación en materiales para envasado activo de alimentos

Abstract

[ES] Se han estudiado las propiedades funcionales de films multicapa activos biodegradables de almidón, con incorporación de Carvacrol (CA) encapsulado en fibras de Policaprolactona (PCL) obtenidas mediante Electrospinning (ES). Los films de almidón se obtuvieron mediante mezclado en fundido y moldeo por compresión y sobre estos films se electro-depositó una disolución de PCL con o sin CA durante diferentes tiempos. Los films con nanofibras se cubrieron con otra capa de almidón para obtener los films multicapa por termocompresión. Así, se obtuvieron 5 formulaciones, dos de ellas con solo PCL entre las capas almidón (con 60 y 90 minutos de electrodeposición), SP1S y SP2S respectivamente y dos formulaciones incorporando CA para los mismos tiempos, SP(CA1)S y SP(CA2)S, respectivamente. También se obtuvo un film control con doble capa de almidón (SS). Los films multicapa acondicionados a 53% de humedad relativa se estudiaron en cuanto a sus propiedades ópticas, barrera al oxígeno y al vapor de agua y propiedades mecánicas. Las fibras obtenidas por ES se analizaron en cuanto a su cinética de liberación del compuesto activo en diferentes simulantes alimentarios con distinta polaridad. Las fibras mostraron una velocidad de liberación del CA mayor, con liberación casi total, en los simulantes menos polares, D1 (etanol 50%) y D2 (Isooctano) (que emulan alimentos grasos), debido a la mayor afinidad del compuesto con estos líquidos apolares. Los films con electrodeposición de PCL, con o sin CA, mostraron valores menores de permeabilidad al vapor de agua, debido a la naturaleza hidrofóbica de la capa de fibras y su efecto barrera en la multicapa. No obstante, no mostraron reducción en permeabilidad al oxígeno, que ya fue baja en los films con solo almidón. Con respecto a las propiedades ópticas, las multicapas presentan valores de brillo relativamente bajos (aspecto mate), una claridad (L) media y tonalidad (h) ligeramente amarilla. En cuanto a las propiedades mecánicas, la presencia de la capa electrodepositada dio lugar a una disminución de la rigidez y resistencia a la rotura de las multicapas. La extensibilidad se vio afectada con la presencia de las capas con CA, reflejando la migración del activo a la capa de almidón, lo que debilitó la matriz.

[EN] The present work studies the functional properties of active biodegradable starch films with encapsulation of Carvacrol (CA) by the Electrospinning (ES) technique. For this, starch films were obtained by melt mixing to obtain the pellet and compression molding using a hydraulic press to obtain the films. On these films, a solution of the biodegradable polymer Polycaprolactone (PCL) with and without Carvacrol was electro-deposited by means of ES and with different times of electro-deposition to obtain the different formulations with which to work in the subsequent tests. Thus, 5 formulations were obtained, two of them with only PCL and starch, at ES duration of 60 and 90 minutes, SP1S and SP2S respectively and two formulations incorporating Carvacrol for the same times, SP (CA1) S and SP (CA2) S, respectively. A control film was also obtained for the tests based on only starch (SS). Once the films were obtained incorporating of the active components, they were thermo-sealed in a hydraulic press in order to obtain the multilayer material. The fibers generated by ES were analyzed in terms of their kinetics of release of the active compound in different food simulants with different polarities. The fibers showed a higher rate of release in the less polar simulants, D1 (ethanol 50%) and D2 (Isooctane) (related to fatty foods) and, on the other hand, in these simulants an almost complete release of the CA was noted, due mainly to the affinity of monoterpene with these nonpolar substances. The starch films carrying electrospun fibers were studied in terms of their optical properties, oxygen barrier, water vapor barrier property, moisture content and mechanical properties. With the addition of the electro-deposited layer of PCL and CA, a reduction of water vapor permeability values against the starch-only film was observed, due to the hydrophobic nature of these two compounds in the films. Regarding oxygen permeability, the presence of PCL did not significantly modify this property that was already exhibited by the thermoplastic starch. With regard to the optical properties, the multilayers have brightness values less than 40 which can be considered matt, have an average lightness (L) and a slightly yellow hue (h). Regarding the mechanical properties, the presence of the PCL layer generated a decrease in the rigidity and breaking strength of the multilayers. The extensibility was affected with the presence of the layers containing the CA, observing less elasticity, perhaps due to the migration of the active, with weakening effect, in the starch layer.