Extrato da folha da Urera baccifera por tecnologia supercrítica comparada às metodologias convencionais

Abstract

Urera bacifera (L.) Gaudich, known as "nettle", has been used in folk medicine. In the region around UTFPR in Francisco Beltrão, a large quantity of this plant is found, thus presenting itself as an accessible and cheap raw material. Published studies on how to obtain extracts and volatile oils from this plant are scarce. Obtaining volatile oils is generally done by steam distillation or maceration. These processes are considered clean and environmentally friendly; however, distillation requires a high energy input, which reflects on operational costs, while maceration requires days of contact with the solvent. An alternative way to obtain plant extracts is through an emerging technology, the Supercritical Fluid Extraction (SFE). It results in high quality extracts, since it can be operated at mild temperatures preserving the thermosensitive compounds. In addition, the supercritical technology does not leave traces of solvents in the product, eliminating the additional unit operation of removing this solvent. The temperature and pressure during SFE are essential parameters, as they directly affect the solvent's ability to solubilize the compounds. The most commonly used fluid in plant matrix extractions is carbon dioxide (CO2). The SFE process has its domain concentrated in the academic area in Brazil, so it requires development for process optimization and industrial scale projection. The implementation of SFE in industries has a high initial cost, but a fast return. Due to the scant number of studies related to Urera baccifera and with the great availability of this plant in the region, this research was idealized, seeking the comparison of the extract obtained by supercritical technology with conventional technologies - steam drag distillation, Soxhlet and maceration. It was also possible to compare the extractions, in terms of yield, with different solvents. The condition that resulted in the highest yield for the supercritical extraction was 60 ºC and 40 MPa. The highest yield was verified for the technique using Soxhlet with ethanol, followed by maceration with ethanol, Soxhlet with hexane and supercritical with CO2. It was found that the extract resulting from steam drag has traces of phenolic compounds and antioxidant activities.