Incorporación de polifenoles a films a base de biopolimeros: propiedades físicas y antioxidantes

Abstract

[ES] Actualmente hay un creciente interés por el desarrollo de envases y/o películas activas, por ejemplo con capacidad antimicrobiana o antioxidante. Estos materiales, aplicados a alimentos, podrían contribuir a alargar la vida útil de los mismos, bien retrasando la aparición de problemas microbiológicos u oxidativos que dan lugar a pérdidas de calidad en el mismo. Estos procesos oxidativos dan lugar normalmente a cambios indeseables en la apariencia y sabor de los alimentos, asociados a cambios de color y otras reacciones químicas y/o enzimáticas. En esos casos, el uso de películas o envases antioxidantes podría ayudar a controlar estos procesos deteriorativos, contribuyendo así a alargar su vida útil. El objetivo del presente trabajo es evaluar la capacidad antioxidantes de películas a base de diferentes biopolímeros y polifenoles extraídos del tomillo, además de otras propiedades físicas de interés.

[EN] Edible films of different formulations based on pea starch (St), chitosan (CH) and hydroxypropylmethylcellulose (HPMC) with glycerol as plasticizer and tannic acid as a cross-linking agent in some chitosan formulations, to improve their mechanical properties, were developed. The films were prepared with and without the addition of lyophilized thyme extract, rich in polyphenol compounds (PP), in the ratio 1:0.15 (polymer:PP). They were conditioned at 25 °C and 75% RH and were characterized its mechanical properties, moisture content, solubility and antioxidant capacity by DPPH method. The results showed that the film properties were affected by the incorporation of polyphenols, so that became more extensible mechanically, increase their water solubility and their antioxidant capacity. Among them, those which showed the best characteristics were chitosan and tannic acid, for their mechanical properties and higher antioxidant activity, because of the greater encapsulation efficiency of polyphenols and cross-linking of tannic acid effect, which also contributed to antioxidant properties of the films obtained.