Extração supercrítica para obtenção de compostos químicos antioxidantes a partir da casca de Acacia mearnsii de Wild

Abstract

Low environmental impact extraction process aligned to bioeconomy concepts have been recently applied to obtain high biological value products. One of them is supercritical carbon dioxide extraction, which can be used as a selective extraction method or as a pre-treatment for a wide range of analytes, such as phenolics. Phenolics are applied in the pharmacological and food industry, as well as recently in advanced materials field, such as biofilms, due to high antioxidant capacity and anti UV capacity. Conventional extraction methods have been used however, the extraction time is high and some interesting compounds may not be fully extracted or degraded in the process, which also makes chemical characterization difficult. So, the aim of this work was applying supercritical carbon dioxide extraction method aligned with ethanol and water to enhance Acacia mearnsii (black wattle or mimosa) bark extract regards to antioxidants, phenolic and condensed tannins compounds. Mimosa extract was incorporate as potential antioxidant agent in the production of more specific materials such as nanocellulosebased films. The tannin powder extracts were characterized by infrared spectroscopy, antioxidant activity, phenolic and tannin content. The effectiveness and potential of mimosa extract on films was evaluated through physical, chemical, thermal and mechanical properties. The extraction by supercritical carbon dioxide and ethanol resulted in decreased extraction time and increased concentration of phenolics and condensed tannin compared to industrial extraction. The water fraction extract used as a reference showed a higher extraction yield, while the ethanol fraction presented a higher antioxidant activity. Demonstrating promising results to extract high antioxidant compounds, phenolics and condensed tannins under pressure atmosphere with absence of light and oxygen. The water fraction was incorporate as antioxidant agent in the formulation of natural films based on nanocellulose and alginate. The supercritical extract decreased the hydrophilicity of these films and the tensile strength was not significantly affected (87 MPa). The alginate provided greater strength, but also increased hydrophilicity. Nanocellulose based supercritical tannin films showed potential characteristics and properties for applications as active films for temporary packaging to increase shelf life of dry foods or pharmaceutical light sensitive products.