Valorização dos polifenóis de casca de espécie amazônica em filmes de quitosana para embalagens ativas

Abstract

In recent decades, there has been growing interest in the development of active food packaging, especially those with antioxidant properties derived from natural compounds. The objective of this study was to evaluate the potential of Protium tenuifolium (Engl.) as a source of condensed tannins, with a view to its application as a functional additive in chitosan biofilms for active packaging. The tannins were obtained by aqueous extraction with the addition of sodium sulfite (3%), quantified based on yield parameters, and characterized by Fourier-transform infrared spectroscopy (FTIR-ATR) and thermogravimetry (TG), which revealed the presence of hydroxyl-aromatic structures and high thermal stability of the extract. Chitosan films containing different concentrations of condensed tannins (3%, 6%, and 9%, based on the dry mass of chitosan) were produced with the addition of glycerol as a plasticizer (20%) and characterized in terms of structure and molecular interactions (FTIR and Raman), surface morphology (SEM), water vapor permeability, opacity, mechanical properties, and antioxidant activity. The addition of tannins increased opacity, reduced water vapor permeability, and enhanced the antioxidant activity of the films in a concentration-dependent manner; the 9% treatment exhibited the best overall performance, including a more uniform and homogeneous surface as observed by SEM. Spectroscopic analyses confirmed interactions between the polyphenols and the polymer matrix, while mechanical strength was preserved at low concentrations and decreased at higher concentrations. Taken together, the results demonstrate that the condensed tannins from P. tenuifolium are promising additives for functionalizing chitosan films, enhancing barrier performance and antioxidant functionality, with potential application in active food packaging.