Evaluación del potencial antioxidante y antimicrobiano de envases de PLA y extracto de piel de almendra mediante su aplicación a alimentos

Abstract

[ES] Se han obtenido films activos a base de ácido poliláctico (PLA) y de un extracto de piel de almendra obtenido con un proceso de extracción subcrítica a 160 y 180ºC. Para evaluar su potencial actividad antioxidante y/o antimicrobiana, se han realizado ensayos de vida útil de dos tipos de alimentos: aceite de girasol y zumo de naranja. El ensayo en el aceite de girasol se realizó en condiciones aceleradas (40ºC), evaluándose el efecto antioxidante de los envases a partir de la evolución del índice de peróxidos, dienos y trienos del aceite a lo largo del tiempo. Por otro lado, la capacidad antioxidante y antimicrobiana de los envases se midió a partir de la evolución de la vitamina C, índice de acidez, color, pH y recuentos microbiológicos del zumo de naranja almacenado en refrigeración a lo largo del tiempo.

[EN] In this work, the antioxidant and/or antimicrobial effectiveness of films based on polylactic acid (PLA) and an extract of almond peel obtained by subcritical water extraction at 160°C was studied on two types of foodstuff: fresh orange juice and sunflower oil. For this purpose, the selected foods were packaged in single-dose containers based on pure PLA (control) and PLA incorporating the extract (PLA- 160) and different physicochemical properties of the foods were analyzed over time. In fresh orange juice, ascorbic acid content, pH, total acidity, Brix, color, and total bacteria, molds and yeast contents were evaluated throughout cold storage. The results indicated that the orange juice packaged in PLA-160 showed less ascorbic acid degradation and less color changes throughout storage. However, the packaging with almond peel extract did not inhibit the bacterial growth, which increased similarly in the two types of packaging (control and PLA-160) throughout the storage time. On the other hand, the antioxidant effectiveness of the packaging was evaluated from the development of the oxidation compounds of sunflower oil in an accelerated life study, based on the determination of the peroxides index (PI) and conjugated diene and triene contents. The PI and diene content increased during the whole storage, being this increase significantly lower (p<0.05) in the packaging with extract. It can be concluded that PLA films incorporating the almond peel extract exhibited remarkable antioxidant activity in the two packaged foodstuffs, but no antibacterial capacity. Therefore, these active films have potential to be used in other products sensitive to oxidative processe