Concentrated extracts of graviola leaves, which are widely discarded during the pruning of trees in commercial crops, were obtained by different membrane concentration process. These leaves are commonly used in traditional medicine due to their pharmacological properties. In this study, hydroalcoholic extracts (with 50 or 70% of ethanol (v/v)) of graviola leaves were subjected to ultrafiltration (UF), nanofiltration (NF) and to combination of both processes (UF followed by NF). The concentrated fractions coming from these processes were analyzed for their total antioxidant capacity and total phenolic content in order to evaluate the selectivity of each concentration step. Processes performance were also evaluated for productivity (permeate fluxes) and energy consumption, which allowed the choice of the best membrane filtration system in terms of energy savings and of interest compounds retention. The combination of processes of UF and NF showed retention coefficients higher than 75% in concentration of phenolic compounds. This sequential design resulted also in higher fluxes of NF, the fluxes increased almost seven times for extracts with 50% of ethanol, and almost three times for extracts with 70% of ethanol when compared to direct processes o NF. Furthermore, the combined system of UF and NF promoted a significant reduction in the concentration time of the extracts by NF and the characterization of fouling mechanisms, which is important parameters to scale-up of this process, indicated that the strategy may increase the useful life of the membranes.
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