PEACH PALM (Bactris gasipaes) SHEATH FLOUR AND PROPOLIS EXTRACT AS BIOACTIVE INGREDIENTS FOR THE DEVELOPMENT OF ACTIVE BIODEGRADABLE FILMS

The growing demand for sustainable packaging has encouraged the valorization of agro-industrial by-products as sources of bioactive compounds for the development of biodegradable materials with functional properties. In this context, this study aimed to develop and characterize active biodegradable films based on cassava starch incorporated with peach palm (Bactris gasipaes) sheath flour and propolis extract, evaluating their effects on the total phenolic and flavonoid contents, antioxidant capacity, and structural characteristics of the films. Biodegradable films were produced using the casting technique. The film-forming solution, composed of cassava starch (4.5%, w/v), glycerol (1.2%, w/v), and peach palm sheath flour (0.65 - 1.35%, w/v), was heated until complete starch gelatinization. After cooling the solution to 45 °C, propolis extract (0.94 - 3.06%, v/v) was incorporated according to a Central Composite Rotatable Design (CCRD). The film-forming solutions were homogenized, sonicated, dried in a forced-air oven at 40 °C, and subsequently conditioned before characterization. The total phenolic content, total flavonoid content, and antioxidant capacity were determined using the DPPH, ABTS, and FRAP assays. Structural characterization was performed by Fourier-transform infrared spectroscopy (FTIR). The CCRD results demonstrated that propolis extract significantly affected total phenolic content, total flavonoid content, and FRAP antioxidant capacity, whereas peach palm sheath flour significantly influenced total flavonoid content and ABTS antioxidant capacity. The formulations exhibited values of up to 19.25 mg gallic acid equivalents (GAE) g⁻¹ film for total phenolic content, 21.48 mg catechin equivalents (CE) g⁻¹ film for total flavonoid content, 15.67 and 20.87 μmol Trolox equivalents (TE) g⁻¹ film for antioxidant capacity determined by the DPPH and ABTS assays, respectively, and 0.26 mmol TE g⁻¹ film for the FRAP assay. Although the DPPH assay did not show a statistically significant effect (p > 0.05), an increasing trend in antioxidant capacity was observed with increasing concentrations of peach palm sheath flour and propolis extract. The FTIR spectra exhibited similar profiles for all formulations, showing the characteristic bands of starch at approximately 3300 cm⁻¹ (O–H stretching), 2930 cm⁻¹ (C–H stretching), 1655 cm⁻¹ (adsorbed water), and between 1150 and 995 cm⁻¹, attributed to C–O–C and C–O stretching vibrations of polysaccharides. Variations in the intensity of the O–H stretching band suggest the formation of hydrogen bonds among starch, peach palm sheath flour, glycerol, and the total phenolic contents present in the propolis extract, indicating good compatibility among the components of the film-forming matrix. These results demonstrate that the combination of peach palm sheath flour, an agro-industrial by-product from the palm heart production chain, and propolis extract represents a promising strategy for the production of active biodegradable films with antioxidant potential, promoting the valorization of agro-industrial by-products and the development of more sustainable food packaging. Acknowledgments: CAPES and CNPq.