EVALUATION OF PRESSURIZED LIQUIDS EXTRACTION COUPLED ONLINE WITH SOLID PHASE EXTRACTION FOR THE PURIFICATION OF BIOATIVE COMPOUNDS FROM BLACK TEA (Camellia sinensis)
Tea leaves are one of the main natural sources of phenolic compounds. Due to the high potential of biological activity of the phenolic compounds present in tea leaves, the production of extracts with high concentration of these compounds can be exploited in several applications. The objective of this work was to produce concentrated and purified fractions in bioactive compounds from black tea leaves, combining pressurized liquid extraction coupled in line with solid phase extraction. Extraction process by pressurized liquids (PLE) coupled to solid phase extraction (SPE) was performed in the integrated EXTRACT-US system. In the first stage of extraction, water was used as solvent for retention of the flavonoids in the solid phase column and selective extraction of gallic acid and caffeine. In the second stage of extraction, methanol was used as solvent, aiming the elution of flavonoids. Two types of C18 solid phase (Sepra C18-E/Silica Base/50 μm and PoraPak Rxn RP/Polymer Base/80 μm) were evaluated as well as different extraction temperatures (40, 60 and 80 ºC). Four well defined fractions were obtained: first fraction rich in gallic acid (0.99 - 1.80 mg/g), second fraction rich in caffeine (6.61 - 10.77 mg/g), third fraction also rich in caffeine (0.16 - 2.70 mg/g) and the fourth methanolic fraction rich in flavonoid compounds (4.61 - 9.68 mg/g) as Mirecetrine, Rutin, Quercetin, Kaempferol-Rutinosid and Kaempferol-Glucoside. Each adsorbent used had an optimal temperature condition for retention and purification of the compounds (Sepra C18-E at 60 °C, PoraPak at 80 °C). Porapak adsorbent recovered 44.00% of gallic acid, 14.65% of caffeine and 14.44% of total flavonoids more than when the Sepra C18-E adsorbent was used. Obtained results were excellent and allowed the production of different concentrated fractions with well defined chemical characteristics.