Biodegradable active packaging films reinforced with thyme waste nanoparticles

This present work introduces a novel strategy combining nanoparticles from thymus vulgaris (nT) infusion waste, incorporated at 1 wt% and 3 wt%, with maleinized corn oil (MCO) as a natural plasticizer into PLA-PHB blend (75 wt% PLA, 25 wt% PHB) The materials were processed by micro-extrusion into films intended for sustainable and biodegradable active packaging applications. Nanoparticle formulation with 3 wt% showed high variation in tensile properties compared to MCO blend with 41% and 75% decrease in tensile strength and elongation at break respectively, otherwise both nanoparticles’ formulations still exhibit increase on ductile reaching 74% and 49% for 1–3 wt% on elongation at break compared with neat PLA. Plasticizer effect of MCO and interaction of nT nanoparticles with the blend was confirmed by calorimetric analysis, showing Tg 15% and 9% decrease for 1–3 wt% respectively. Results of colour and UV characterization suggest that the films could interfere with light incidence while maintaining high transparency. During composting test, it was observed that the addition of nanoparticles delayed the degradation grade, although all samples were composted within 30 days. Furthermore, the nanoparticles improved the oxygen barrier properties of developed films, leading to a reduction of above 40% for both nanoparticles’ formulations in OTR-e values. In addition, nanoparticles highly increased antioxidant activity with 67% and 75% for 1–3 wt%, interesting findings to develop sustainable, biodegradable and active materials for food packaging applications.