Otimização de extração de compostos fenólicos de própolis verde e aplicação em biofilme de quitosana

Abstract

Propolis is a complex mixture produced by bees from various plant sources. It has significant biological properties, such as antioxidant, antibacterial, antiviral, and antifungal properties. Due to these biological activities, biofilms prepared from biodegradable polymers, incorporated with propolis extracts, can be alternatives for developing food packaging. However, as propolis is a resinous material with a high wax content, it is necessary to carry out an inheritance process to obtain the compounds of interest. Thus, this study aimed to optimize the process of extraction of phenolic compounds from green propolis and apply the optimized extract in chitosan biofilms. The extracts were elaborated from the experimental design with mixtures of three solvents (water, ethanol, and ethyl acetate) generated in 14 plans. From the quantification of total phenolics of all extracts obtained, it was possible to find the best proportion of extractor solvents: 47.0 % water with 35.0 % ethanol and 18.0 % ethyl acetate. After preparing an extract at the optimized point, it was observed that the theoretical values of phenolic compounds and the minimum inhibitory concentration against Staphylococcus aureus, Bacillus cereus, and Escherichia coli were close to those obtained experimentally. Next, the optimized extract was incorporated into a chitosan biofilm prepared by casting. After characterization tests, it was possible to verify that there were no differences in thickness, water solubility, and water vapor permeability concerning the biofilm without extract. Through optical and scanning electron microscopy, it was possible to visualize the homogeneity of the formed biofilms and certify that the addition of propolis extract did not affect its microstructure, indicating good compatibility. The association of the extract with the chitosan biofilm showed antioxidant potential, with the release of the extract in the medium reaching after 24 hours, a value of 28.31 µmol Trolox L-1 equivalent through DPPH analysis. As for the antimicrobial activity of the film, the release of the extract in the culture medium was observed, provoked in a more minor experience of the bacteria Staphylococcus aureus and Bacillus cereus. In this way, it is possible to consider that the optimization of the extraction of phenolic compounds from propolis presents antioxidant and antimicrobial actives, and it is feasible for incorporation in chitosan biofilms, which can be used in food packaging.