Additionally, it enables product separation, which is of particular interest as some by-products formed through L-DOPA spontaneous overoxidation (e.g. dopamine or dopaquinone) tend to polymerize and complicate purification. The EMR configuration facilitates the separation of these by-products via membrane filtration, ensuring continuous purification of L-DOPA on the permeate side. However, L-DOPA spontaneous oxidation remains problematic as it hampers the yields and productivity of such enzymatic process. To address this, Donato et al. attempted to continuously introduce ascorbic acid 162 , a reducing agent, while simultaneously removing the biocatalytically produced L-DOPA. To this aim, the authors immobilized tyrosinase on a polyamide tubular membrane sponge layer, and implemented the EMR in cross-flow configuration. It resulted that the continuous removal of L-DOPA from the reaction environment, along with the antioxidant effect of ascorbic acid, further enhanced L-DOPA productivity, reaching 1.60 U.mg -1 , i.e. higher than that of other processes reported in literature (where product separation and ascorbic acid addition were not applied).