Bionanocomposites based on Polylactide (PLA) and Polyhydroxybutyrate (PHB) blends were successfully obtained through a combined extrusion and impregnation process using supercritical CO₂ (scCO₂). Graphene oxide (GO) and cinnamaldehyde (Ci) were incorporated into the blends as nano-reinforcement and an active compound, respectively, separately, and simultaneously. From the results, cinnamaldehyde quantification values varied between 5.7% and 6.1% (w/w). When GO and Ci were incorporated, elongation percentage increased up to 16%, and, therefore, the mechanical properties were improved, with respect to neat PLA. The results indicated that the Ci diffusion through the blends and bionanocomposites was influenced by the nano-reinforcing incorporation. The disintegration capacity of the developed materials decreased with the incorporation of GO and PHB, up to 14 and 23 days of testing, respectively, without compromising the biodegradability characteristics of the final material.

It is known that ethylene plays an important role in the quality characteristics of fruits, especially in storage. To avoid the deterioration of fruits caused by ethylene, titanium dioxide (TiO₂) has been used due to its photocatalytic capacity. The aim of this study was to develop films based on two types of biopolymers, Mater-Bi (MB) and poly-lactic acid (PLA), with nanoparticles of TiO₂ and to determine their ethylene removal capacity and its application in bananas. First, the films were fabricated through an extrusion process with two different concentrations of TiO₂ (5 and 10% w/w). Then, the films were characterized by their structural (FTIR), morphological (SEM), thermal (DSC and TGA), dynamic (DMA), barrier, and mechanical properties. The ethylene removal capacities of the samples were determined via gas chromatography and an in vivo study was also conducted with bananas for 10 days of storage. Regarding the characterization of the films, it was possible to determine that there was a higher interaction between PLA with nano-TiO₂ than MB; moreover, TiO₂ does not agglomerate and has a larger contact surface in PLA films. Because of this, a higher ethylene removal was also shown by PLA, especially with 5% TiO₂. The in vivo study also showed that the 5% TiO₂ films maintained their quality characteristics during the days in storage. For these reasons, it is possible to conclude that the films have the capacity to remove ethylene. Therefore, the development of TiO₂ films is an excellent alternative for the preservation of fresh fruits.

Polylactic acid (PLA) nanocomposites with two antimicrobial agents based on copper modified montmorillonite (MtCu 2+ and MtCu 0) were developed in order to obtain a lower environmental impact material with antimicrobial activity for potential use in food packaging. Clay modification was permorfed by cation exchange between MtNa + and a copper salt obtaining MtCu 2+ and its followed reduction with NaBH 4 obtaining MtCu 0. Then PLA nanocomposite films (MtCu 2+ / PLA and MtCu 0 /PLA), using different concentration of MtCu 2+ and MtCu 0 (1, 3 and 5 wt.%) were obtained by casting technique. X-ray diffraction (XRD) and Transmission electronic microscopy (TEM) analysis evidenced a certain degree of intercalation of the modified clays in the nanocomposites. Thermal, mechanical and optical properties showed variations by incorporating MtCu 2+ and MtCu 0 in the polymer matrix. On the other hand, it was possible to evidence antimicrobial activity of the nanocomposites (ASTM Standard E2149) against to Escherichia coli ATCC 25922 and Listeria innocua ATCC 33090 obtaining a 99% maximum of reduction to both bacteria.

In this work, a colorimetric indicator based on gold nanoparticles (AuNP) and a biodegradable and eco-friendly polymer (sodium alginate, Alg.), was developed for the real-time detection of fish spoilage products. The AuNPs and the colorimetric indicator were characterized using UV-VIS, FTIR spectroscopies, TGA, DSC, XRD, TEM, and colorimetry. The UV-VIS spectrum and TEM showed the successful synthesis, the spherical shape, and the size of AuNPs. The results indicated color changes of the indicator in packaged fish on day 9 of storage at a refrigerated temperature (5 °C. These results showed the successful application of the colorimetric indicator in the detection of TVB-N in packaged fish.