Preparation and characterization of hybrid polymeric coating films of chitosan–clay loaded with açaí extract (Euterpe oleracea) for application in food and pharmaceutical areas

This study aimed to study the interaction between two different açaí extracts used in synthesis of hybrid polymeric films based on chitosan–clay and evaluate its morphological and physical–chemical properties, indeed antibacterial and antioxidant activities. Films with acidified açai extract (FEAA) and non-acidified açai extract (FEBANA) were prepared using the casting method. It was possible to observe a surface with a rough appearance, varying according to the added extract concentration using SEM photomicrographs. The reflection peaks were similar to the Chit–Clay film (2θ = 14° and 16.8°) and the reduction in the degree of chitosan crystallinity for the FEBANA films in relation to FEAA films. The TG data also show that the FEBANA films have a higher percentage of water of hydration than the FEAA films, corroborating this state of anhydrous films for FEAA and state of hydrated films for FEBANA. The FEBANA films were two stretches in the region between 842 and 962 cm⁻¹, and a shoulder 1095 cm⁻¹ covered by bands 1025 cm⁻¹ (Si–O–Si) and can attributed to the PEG plasticizer. This greater detection of PEG stretches in the FEBANA films suggests a greater concentration of PEG on the surface of the FEBANA film. MIC microbiology demonstrated that both types of extracts were capable of inhibiting Gram (−) strains, Escherichia coli and Pseudomonas aeruginosa, and Gram ( +) strains, Staphylococcus aureus and Staphylococcus epidermidis. In disk diffusion, the acidified extract showed inhibition activity for Edwardsiella tarda, Enterococcus faecium and Streptococcus pyogenes. Both extracts are effective in inhibiting the growth of both Gram (−) and Gram ( +) bacteria. The FEAA polymeric films showed a higher degree of recovery, reversible chemical bonding with the matrices and consequently greater DPPH free radical scavenging capacity compared to the FEBANA polymeric films. The FEAA and FEBANA films present characteristics of releasing active ingredients from the hybrid polymeric film and can be applied in edible packaging or use in biodegradable smart packaging or as food biopreservative; or even, in pharmaceutical release systems for releasing active ingredients onto the skin, as organic active ingredient release membranes for skin health and beauty, wound healing or even as adjuvants in tissue bioengineering for skin reconstruction after burns and in plastic skin surgery as biodegradable films.