The aim of this work was to evaluate the influence of halloysite clay nanoparticles - unmodified (Hal) and organically modified (mHal) - and oregano essential oil (OEO), used as an antimicrobial agent in active packaging, on the biodegradation behavior of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) films. Five samples were prepared by melt mixing using 3 wt% clay, and 8 wt% and 10.4 wt% OEO. PHBV compositions containing OEO presented the highest rate of biodegradation, achieving 46% of mass loss after aging for 12 weeks in simulated soil. The addition of clay nanoparticles reduced the polymer\'s biodegradation to 32%. The compositions containing OEO showed a rough and layered surface with visible cracks, indicating degradation occurring through layer-by-layer erosion from the surface. This degradation was confirmed by the chemical changes on the surface of all samples, with a slight decrease in molar masses. The composition containing 8 wt% OEO presented an increase in the crystallization degree as a result of the preferential consumption of amorphous phase, whereas for the compositions containing clay nanoparticles, both crystalline and amorphous regions were degraded at similar rates. Therefore, the combination of additives allows the biodegradation process of PHBV to be controlled for use in the production of active packaging.

The aim of this work was to develop active packaging based on polypropylene (PP) and polylactic acid (PLA) matrices using a high value by-product extracted from orange peel as an active compound for food packaging applications. Different films with and without orange peel extract (OPE) based on PP and PLA were obtained via cast extrusion and characterized in terms of their mechanical, thermal, optical, and sealing properties. The films obtained were transparent, but when OPE was incorporated, the transmittance spectrum decreased, causing slight coloration. Mechanical properties were affected by the incorporation of OPE, as elongation at break and tensile strength increased in the cross-direction of the PP film, although the main differences found were related to the polymer itself. In addition, sealing strength also increased via the incorporation of OPE in the PP matrix. However, thermal properties were not affected by OPE in the PP matrix but slightly decreased stability in PLA. Regarding antimicrobial activity in in vitro studies, no inhibition of the growth of Listeria innocua, Saccharomyces cerevisiae, Aspergillus niger, or Escherichia coli was observed. Finally, antioxidant activity was observed in in vitro studies with 2,2-Diphenyl-1picrylhydrazyl (DPPH) radical. The results of this study showed that the obtention of materials with OPE incorporated into the PLA and PP matrix is feasible. The new materials obtained can be used for applications of oxidation-sensitive fresh products.

In this work, alpha-tocopherol (α-TOC) was encapsulated in poly(lactic acid) nanoparticles (PLA NPs) and added to low-density polyethylene (LDPE) films with the aim of producing an active film for food packaging applications. PLA NPs loaded with α-TOC were produced through nanoprecipitation and dried using two methods (freeze-dryer and oven). LDPE-based films with final polymeric matrix concentrations of 10 and 20 g/kg were then produced through blow extrusion. The results showed that LDPE-based films loaded with α-TOC can be produced using blow extrusion, and a good distribution of PLA NPs can be obtained within the LDPE matrix as observed using scanning electron microscopy (SEM). The mechanical properties were affected by the incorporation of α-TOC and PLA NPs loaded with α-TOC, with the observation of a decrease in tensile strength and Young\'s Modulus values and an increase in elongation at break. Regarding water vapor permeability, the films showed a reduction in the values with the addition of α-TOC and PLA NPs loaded with α-TOC compared to the LDPE film (control). Films with α-TOC in the free state and loaded in PLA NPs showed antioxidant activity, but their behavior was affected by the encapsulation process.

Ethylene is a phytohormone that is responsible of fruit and vegetable ripening. TiO2 has been studied as a possible solution to slowing down unwanted ripening processes, due to its photocatalytic capacity which enables it to remove ethylene. Thus, the objective of this study was to develop nanocomposites based on two types of eco-friendly materials: Mater-Bi® (MB) and poly(lactic acid) (PLA) combined with nano-TiO2 for ethylene removal and to determine their ethylene-removal capacity. First, a physical-chemical characterization of nano-TiO2 of different particle sizes (15, 21, 40 and 100 nm) was done through structural and morphological analysis (DRX, FTIR and TEM). Then, its photocatalytic activity and the ethylene-removal capacity were determined, evaluating the effects of time and the type of light irradiation. With respect to the analysis of TiO2 nanoparticles, the whole samples had an anatase structure. According to the photocatalytic activity, nanoparticles of 21 nm showed the highest activity against ethylene (~73%). The results also showed significant differences in ethylene-removal activity when comparing particle size and type and radiation time. Thus, 21 nm nano-TiO2 was used to produce nanocomposites through the melt-extrusion process to simulate industrial processing conditions. With respect to the nanocomposites\' ethylene-removing properties, there were significant differences between TiO2 concentrations, with samples with 5% of active showed the highest activity (~57%). The results obtained are promising and new studies are needed to focus on changes in material format and the evaluation in ethylene-sensitive fruits.

Gelatin (bovine/porcine)-based edible films are considered as an excellent carrier for essential oils (EOs) to preserve food quality and extend their shelf life. Spearmint essential oil (SEO) is known for its potential antioxidant and antimicrobial effects; nevertheless, its food applications are limited due to the volatile nature of its active components. Thus, edible films loaded with essential oil can be an alternative to synthetic preservatives to improve their food applications. In the present study, the effect of SEO addition was investigated on the physicochemical properties of bovine and porcine gelatin films, and antioxidant activity was assessed. GCMS (Gas chromatography mass spectrometry) analysis revealed the presence of carvone (55%) and limonene (25.3%) as major components. The incorporation of SEO into the films decreased the opacity, moisture content, water solubility, and elongation at break of bovine and porcine gelatin films. However, with the addition of EO, the thickness and water vapor permeability of bovine and porcine-based gelatin films increased. Moreover, the addition of SEO increased the tensile strength (TS) of the porcine-based film, whereas bovine samples demonstrated a decrease in tensile strength. XRD (X-ray diffraction) findings revealed a decrease in the percentage crystallinity of both types of gelatin films. SEM (scanning electron microscope) results showed the changes in the morphology of films after the addition of SEO. Antioxidant properties significantly increased with the incorporation of EO (p < 0.05) when compared with control films. Therefore, the addition of SEO to gelatin-based edible films could be an effective approach to prepare an active food packaging material to prevent food oxidation.

The regular release kinetics of active ingredients is inconsistent with the demand of meat preservation. Herein, the pH-triggered dynamic mechanism of packaging film was developed based on L100 polymer incorporated with Cinnamon essential oil (CEO) by coaxial electrospinning. The acquired results revealed that UV-vis and fluorescence spectra confirmed the pH release behavior. The fabricated film was quickly dissolved and transformed from solid to liquid phase, resulting in a faster release rate of CEO from 68.9 % to 98.2 % with the pH increasing. The morphological structure verified the core-shell structure formation with a specific surface area value of 7.22 m2/g. The live/dead results of bacteria indicated good antibacterial efficacy against E. coli and S. aureus. The pH-sensitive film successfully extends the shelf-life of griskin by 3 days. In conclusion, this work will aid in optimizing durability of active ingredients in packaging.

Active packaging films were prepared by adding red cabbage anthocyanin extract (RCAE) into acetylated distarch phosphate (ADSP). This paper investigated the influence of the interaction relationship between RCAE and the film matrix on the structure, barrier, antioxidant and release properties of active films. Sixteen principal compounds in RCAE were identified as anthocyanins based on mass spectroscopic analysis. Micromorphological observations indicated that the RCAE distribution uniformity in the films decreased as the RCAE content increased. When the concentration of RCAE was not higher than 20%, the moisture absorption and oxygen permeability of films decreased. The stability of RCAE in the films was enhanced by the electrostatic interaction between RCAE and ADSP with the formation of hydrogen bonds, which facilitated the sustainability of the antioxidant properties of films. The release kinetics of RCAE proved that the release rate of RCAE in active films was the fastest in distilled water, and Fickian’s law was appropriate for portraying the release behavior. Moreover, the cytocompatibilty assay showed that the test films were biocompatible with a viability of >95% on HepG2 cells. Thus, this study has established the suitability of the films for applications in active and food packaging.

The influence of film structure on the release kinetics of sodium benzoate (SB) from polymeric films is addressed in this study. In particular, four film structures were investigated, two monolayer and two multilayer systems. In particular, in one case, the active substance was uniformly distributed into a chitosan-based matrix, and in the other one, it was previously incorporated into alginate beads before dispersion in the chitosan film, thus realizing two types of monolayer films; on the other hand, the same chitosan film with SB encapsulated in alginate beads was used as the inner layer of a multilayer system constituted by two side films of alginate. The two alginate-based layers were made with two different thicknesses, thus producing a total of two multilayer systems. The release of SB from the above-mentioned films in water was studied by means of a UV/VIS spectrophotometer at 227 nm. A first-order kinetics-type equation was used to quantitatively describe the release data. Results suggest that the film structure strongly affected the release kinetics. In fact, monolayer films showed single-stage release kinetics, whereas the two investigated multilayer systems showed two-stage release kinetics. Further, the presence of alginate beads strongly affected the SB release, thus suggesting the potential of encapsulation to control the release mechanism of active compounds.

Oxidative deterioration is one of the most important factors limiting shelf-life of fatty food products, where the use of active packaging produced with natural antioxidants is a strategy to minimize these reactions. Poly(acid lactic) (PLA) films were produced with carotenoids extracts rich in beta-carotene, lycopene, and bixin. The kinetics of carotenoids\' release to a fat simulant was evaluated and successfully explained by a new mathematical release model which considered the degradation of the migrants after their release. In the presence of light, films with lycopene and beta-carotene protected sunflower oil mainly by their light barrier properties, and secondly by their barrier to oxygen and antioxidant gradual releasing. The films produced with bixin presented the best performance as antioxidant active packaging to sunflower oil, where differences found in films barrier properties and in the transfer coefficients among the carotenoids were influenced by their molecular structures.

Films made of plasticized starch (PLS)/poly(butylene succinate co-butylene adipate) (PBSA) blends were prepared by thermomechanical processing varying the PBSA proportions in blends to obtain biphasic materials with distinct morphologies. These morphologies were characterized by selective extraction of each phase, microscopic observations, and selective water/oxygen permeation properties. These experiments allowed identifying the blend compositions corresponding to the beginning of partial continuity (cluster partial percolation) until total continuity of each phases. This property was related to the controlled release of model molecule (fluorescein) previously dispersed in the PLS and revealed that its release depended on the tortuosity of the PLS phase tailored by the polymer blends composition and by the limited swelling of the PLS when entrapped in the PBSA phase. Future applications will focus on food preservatives dispersed in PBSA-PLS blends to obtain active antimicrobial packaging put in direct contact with intermediate to high moisture foods.