Antioxidant blend films of PLA and PVA with almond skin powder to preserve toasted almonds

Abstract

The development of sustainable food packaging that minimizes the environmental impact of plastics, making use of natural resources, is necessary. In this regard, mixed PLA and PVA (75 : 25) films with and without almond skin powder have been studied for their ability to prevent the oxidation of roasted almonds during storage. PLA was dispersed homogeneously in the PVA matrix with good interfacial adhesion, modifying the crystallization of PVA. PLA reduced the water vapour permeability (WVP) of PVA by 50%, while increasing the oxygen permeability (OP) (56%) in the blend films. However, the incorporation of AS powder reduced OP values of blend films below that of neat PVA, without a significant increase in WVP. AS powder promoted the stiffness of the blend films (by 233%) reducing their extensibility (by 50%), but without significant effect on the resistance to break. Likewise, the PLA/PVA-AS films reduced the oxidation rate of packaged toast almonds during storage at 25 °C and 53% RH for 6 months, in comparison with the control films. Therefore, PVA/PLA-AS films represent a sustainable alternative for packaging low moisture foods sensitive to oxidation, while contributing to valorisation of a highly produced agri-food waste.