Preliminary comparative study of the extraction of phenolic compounds with water from yerba mate by non-isothermal subcritical and conventional isothermal processes

Resumo

With the crescent interest of the industries in phenolic compounds-rich aqueous extract, new extraction methodologies must be evaluated on their technical and environmental efficiencies. In the current work, the extraction of phenolic compounds from yerba mate is evaluated using the non-isothermal subcritical water extraction technique. The extraction was conducted with a solid-liquid ratio of 0.5 g 100 mL^-1, with a final temperature of 120 °C and a heating ramp of 5 °C min^-1. Additionally, a conventional batch extraction at 70 °C was conducted in a non-pressurized system, and the energetic demand for the production of 1 m³ of crude yerba mate extract for both scenarios was estimated. Both the extraction methods presented a similar concentration of phenolic compounds (up to 527 mg GAE L^-1), with a total extraction time of 161 and 128 min for the conventional and non-conventional extraction processes, respectively. The non-conventional process resulted in an increase of 111 % in the energy consumption of the conventional one, which suggests that the batch extraction conducted with water at 70 °C is more efficient in environmental aspects.