Filmes extrusados de blendas biodegradáveis à base de polissacarídeos e proteína ativados com óleo essencial de cravo encapsulado em nanopartículas de quitosana

Abstract

Environmental concerns and strict regulations on plastic waste have driven the development of alternatives to synthetic polymers, such as biodegradable packaging. These packaging materials can incorporate clove essential oil, whose volatility and instability are overcome by encapsulation in chitosan nanocapsules. The objective of this study was to develop biodegradable films made from corn starch, chitosan, and whey protein isolate, incorporating chitosan nanocapsules loaded with clove essential oil. The research was conducted in two main stages. In Article 1, chitosan nanocapsules containing clove essential oil (CEO) were developed and characterized. Four formulations of nanocapsules with different chitosan/CEO ratios were tested: 1:0, 1:0.50, 1:0.75, and 1:1. The encapsulation efficiency ranged from 1.08% (1:0.50) to 12.14% (1:1), being influenced by the concentration of essential oil. The antioxidant activity increased with the proportion of CEO, reaching 75.84% in the 1:1 formulation. The hydrodynamic diameter of the nanocapsules was 61 nm for 1:0 and 58 nm for 1:1, while scanning electron microscopy (SEM) analysis revealed particles with an average size of 94 nm for 1:1. Thermogravimetric analysis (TGA) indicated that the chitosan polymer matrix provided greater thermal stability to the CEO. In the second stage, described in Article 2, the nanocapsules were incorporated into biodegradable films. Three types of films were developed: control (without nanocapsules), NpQ (nanocapsules without CEO), and NpQ+CEO (nanocapsules containing clove essential oil, 1:1). The NpQ+CEO formulation exhibited higher antioxidant activity (31.64%) compared to the control film (11.65%) and the NpQ film without oil (18.34%). The thermal stability of the films was also improved, with the decomposition peak of the NpQ+CEO film reaching 315°C, while the control film degraded at 310°C. The analysis of CEO diffusion in the films followed Fick's law, adjusting to a two-stage model. In the first stage, a rapid release of 56% of the CEO was observed, with a diffusion coefficient (D1) of 8.10 × 10⁻⁸ cm²/s, indicating accelerated diffusion due to the high concentration of essential oil in the nanocapsules near the surface of the film. In the second stage, a slower and controlled release of CEO occurred, associated with diffusion through the polymer matrix of the film, with a diffusion coefficient (D2) of 2.68 × 10⁻⁹ cm²/s. This behavior confirms that CEO encapsulation promotes gradual and sustained release over time. The addition of nanocapsules also resulted in better structural uniformity, reduced transparency of the films, and lower water vapor permeability, without compromising their mechanical strength. The results demonstrate that incorporating chitosan nanocapsules loaded with clove essential oil enhances the functional properties of biodegradable films. These active packaging materials not only exhibit antioxidant potential and improved thermal stability but also represent a sustainable alternative to conventional plastics. Thus, the use of these nanocapsules in biodegradable films can contribute to reducing the dependence on synthetic polymers, offering an innovative and ecologically viable solution for the packaging industry.