Tecnologia de fluido supercrítico como ferramenta para obtenção de extrato de erva-mate (Ilex paraguariensis)

Abstract

The compounds present in the yerba mate are recognized for their health benefits, with emphasis on chemo-preventive activity, inhibition of oxidative stress, intestinal propulsion and the vasodilator and choleretic effect. Among the bioactive compounds present in yerba mate, methylxanthine alkaloids, especially caffeine and theobromine, are well known for their central nervous system stimulating properties and phenolic compounds with antioxidant action. Thus, to evaluate if the technology of supercritical extraction is effective in obtaining extracts of leaves, stem and flower of mate, as well as the characteristics of the extracts obtained were the main objectives of this work. For this, the pressure conditions and extraction temperatures were optimized for the overall yield (R∞), yield at constant extraction rate (RCER) and time at constant rate extraction (tCER) for mate leaves. The operating pressure of the ES-CO2 system positively influenced the extraction of extracts of mate leaves. At 32 MPa and 58 ° C it was possible to obtain 8.78% of extract in relation to the mass of raw material. When this condition was applied to stems and flowers, extraction yields of 1.37% and 2.24%, respectively, were obtained. The extraction kinetics were evaluated through the Spline model, which considers three stages of extraction. The model fitted well to the experimental data, presenting coefficients of determination (R 2 ) higher than 0.99. The times of the constant rate of extraction stage were determined between 23.7 and 60.6 min, which was responsible for obtaining about 40% of the total extract. The quantification and identification of the extracts were evaluated by high performance liquid chromatography (HPLC) and FTIR. The main compounds identified were the methylxanthines caffeine and theobromine. The extracts of flowers, stems and flowers presented 35.5 and 5.5 mg / g, 63.9 and 9.6 mg / g and 43.1 and 48 mg / g of caffeine and theobromine, respectively. However, the extracts presented low antioxidant activity. In optimized conditions, ES-CO2 is a viable technique to obtain extracts of yerba mate especially for the extraction of compounds of medium polarity, such as caffeine and theobromine, with potential application in food, contributing to the evaluation of the productive chain of this product.