Biosynthesized metal nanoparticles from agro-industrial byproducts applied in the functionalization of bioplastics for use in the blueberry packaging

In this study, silver (Ag), zinc oxide (ZnO), and silicon dioxide (SiO2) nanoparticles (NPs) were synthesized using phenolic compound-rich extracts from agro-industrial by-products of blueberries and asparagus. The NPs exhibited average sizes of 3.07 f 2.38 nm (Ag), 70.42 f 18 nm (ZnO), and 104.38 f 11.7 nm (SiO2) with high colloidal stability (Z potentials:-35.63 mV for Ag,-33.9 mV for ZnO, and-10 mV for SiO2). Bioplastics functionalized with these NPs showed improved properties: increased rigidity (Young's modulus up to 2690 MPa in B-SiO2), reduced water absorption (160.64 g/100 g dry matter in B-Ag), high transparency (87.87 % in BControl, 87.83 % in B-ZnO), and lower wettability (contact angle of 102.4 degrees in B-ZnO). Thermal stability also improved, with B-SiO2 exhibiting the lowest mass loss (31.12 %) in TGA. Bioplastics with Ag demonstrated strong antimicrobial activity, maintaining low mold and yeast counts (<10 CFU/g). Biodegradation was faster in soil than in marine environments, with NPs modulating rates. As primary and secondary packaging for blueberries, Ag-functionalized bioplastics reduced mass loss and preserved firmness for up to 56 days at 4.3 degrees C, with no NP migration detected by XRF and FTIR. This research highlights a sustainable approach using agro-industrial by-products to develop functional bioplastics, aligning with circular economy principles and reducing environmental impact in the food packaging sector.