Efeito da nanoencapsulação de fração rica em flavonoides do resíduo agroindustrial de Malpighia emarginata DC (acerola) em filmes ativos antioxidantes

Abstract

The incorporation of natural antioxidants into active packaging is an effective strategy to mitigate oxidation and preserve food quality. Nanoparticles are widely used to improve the dispersibility, stability and efficacy of these antioxidants in packaging materials. This study developed polyvinyl alcohol (PVOH) antioxidant films incorporated with a flavonoid-rich fraction (FLA), obtained from the Malpighia emarginata D.C (acerola) pomace extract - (MEPE) residues, in free and nanoencapsulated form. PuroSorb PAD950 resin was applied to enrich flavonoids from MEPE and then their nanoencapsulation using nanocapsules (NC), liposomes (LP) and nanogels (NG) was evaluated. The resin showed high adsorption capacity (19.20 ± 0.93 mg/g), with adsorption and desorption rates of 74.83 ± 1.80% and 96.76 ± 4.67%, respectively. The dynamic process produced a flavonoid-rich fraction (FLA) with flavonoid enrichment up to 20-fold and enhanced antioxidant activity (7.8-, 9.9-, and 6.7-fold in DPPH, ABTS, and FRAP assays) compared to crude MEPE. FLA-LP showed the smallest particle size (103.4 ± 5.6 nm) and the highest zeta potential (-54.87 ± 1.21 mV), while FLA-NC showed the lowest PDI (0.0848 ± 0.0166) and the highest encapsulation efficiency (81.43 ± 0.98%). FLALP and FLA-NG further improved the antioxidant capacity compared to the non-encapsulated fraction. The nanoencapsulates exhibited suitable physical properties for practical applications and the results demonstrated enhanced antioxidant activity compared to free FLA. FLA-NC were selected for application to PVOH films because they showed good properties and the best compatibility with the film-forming solution. The PVOH films were produced by the casting technique. After obtaining the PVOH films, control (FC) and formulations with 1% (w/w) of free FLA (FL) and nanoencapsulated (FN). These were characterized regarding the migration of flavonoids in simulant media and their antioxidant, mechanical, barrier, thermal, structural and optical properties. The incorporation of free FLA and its nanoparticles reduced the crystallinity of the FL and FN films, resulting in lower tensile strength and greater permeability to water vapor. In addition, the films presented greater opacity, yellowing index and protection against UV-visible radiation. The thermal properties underwent minor changes, without compromising the applicability. In addition, the successful incorporation of the rich fraction (free and nanoencapsulated) expanded the antioxidant functionality of the films, with emphasis on FN, which promoted the controlled release of bioactive compounds. This behavior reinforces the potential of the films developed for active packaging, especially in the preservation of foods susceptible to oxidation.