Hidrogeles de almidón-PVA como vehículos de antimicrobianos para el envasado activo de alimentos

Abstract

[EN] In the present work, hydrogels of starch-PVA (poly vinyl alcohol) were obtained by freezing-thawing cycles, with and without incorporation of polycarboxylic acids (citric acid and maleic acid). Their microstructure and capacity to absorb antimicrobial agents (cinnamon essential oil: CEO) as aqueous emulsion with emulsifying gelatin was analyzed. Impregnated hydrogels where incorporated into the packaging of fresh-cut apple (var. Granny Smith) to study of the antimicrobial effect of the active compound released in the packaging head space throughout cold storage (10ºC). Density, pH, particle size and ζ-potential of the gelatin-CEO aqueous dispersions were determined, as well as the microstructure, the crosslinking degree and the impregnation capacity of the hydrogels. For the microbial analysis fresh cut apple samples were inoculated with Lysteria innocua and stored in closed bottles containing impregnated hydrogels with active compounds. Microbial counts were carried out at 2, 5 and 8 storage days. The microbial analysis revealed differences in the active compound release from the hydrogels according to their pore size and the chains crosslinking. The hydrogels without acid incorporation, with bigger pore size, released more quickly the active compound, showing notable antimicrobial action at the first control time. However, the hydrogels with maleic acid incorporation, with greater crosslinking degree, released the active compound after 8 storage days, where their effective antimicrobial activity was observed.

[ES] Se obtenido y caracterizado hidrogeles de almidón-PVA, se han impregnado con dispersiones acuosas de aceite esencial de canela y gelatina y se han incorporado en envases de manzana cortada inoculada con Listeria inocua para el análisis de la actividad antimicrobiana del aceite esencial liberado en el espacio de cabeza del envase desde el hidrogel. La diferente actividad se ha utilizado para deducir la cinética de liberación del antimicrobiano en función de la estructura del hidrogel.