Development and Characterization of a Biodegradable Film Using Copaifera officinalis Essential Oil-Loaded Starch Microparticles

Abstract

This study evaluated the effects of the incorporation of copaiba essential oil in corn starch in encapsulated and direct forms in films formulated with poly(vinyl alcohol), polyvinylpyrrolidone, and propylene glycol. The characterization of the essential oil, performed via gas chromatography coupled to mass spectrometry, identified β-caryophyllene as the main sesquiterpene. From the oil, a nanoemulsion was developed that, after spray drying, provided the microparticles used in the production of films using the casting technique. The encapsulated copaiba essential oil (CEO) showed an encapsulation efficiency (%) of 76.12% ± 0.15. Thermogravimetric analysis revealed that the encapsulated CEO microparticles showed higher thermal stability than free essential oil, preserving the structural integrity of their compounds even at high temperatures. The F3 film containing encapsulated CEO presented the lowest thickness (0.48 ± 0.05) and the lowest moisture content (16.07 ± 0.06) compared to the F2 film with CEO in the nonencapsulated form and the F1 control film, evidencing a more stable interaction between the encapsulated oil and the starch matrix. The hydration capacity of F3 was positioned between those observed in the F1 and F2 films, suggesting that the encapsulation technique improved the structural compatibility and improved water retention over time. The F1 film presented a tensile strength of 5.15 MPa, while the F3 and F2 films presented slightly higher values of 5.41 and 5.33 MPa, respectively. The modulus of elasticity of F1 was 1.40 MPa. In comparison, F2 showed a decrease, registering 1.28 MPa, which indicates greater flexibility, and F3 showed a slight increase, reaching 1.45 MPa, suggesting a relatively greater rigidity. The F3 film indicated a significant increase in elongation, reaching 41.79%, compared to F1’s 27.07% and F2’s 28.74%. These results suggest that encapsulation improved the ductility and mobility of the polymer chains, demonstrating the best balance between strength, rigidity and flexibility compared to the F1 and F2 films. In the FTIR spectra, it was evident that the addition of the encapsulated CEO affected the chemical structure of the film, as it demonstrated changes in the bands of the region 1750–1000 cm^–1, revealing that there were different interactions of the oil with the polymer matrix. These findings reinforce the promising use of encapsulated CEO in pharmaceuticals, healthcare, and biodegradable packaging.