Peptidases catalyze their production through protein hydrolysis (Figure ). However, it is established that the efficiency of peptidases decreases upon accumulation of the hydrolysis products (i.e. soluble peptides and amino acids) in the medium . Here, conducting protein hydrolysis in continuous membrane reactors (i.e. through size-exclusion membrane operations) enables the separation of lowmolecular-weight peptides from protein hydrolysates, thereby overcoming the drawbacks of batch reactions, such as product inhibition, low process productivity, and excessive hydrolyses (i.e., prevention of side reactions) 34 . Additionally, the continuous feeding of substrates (e.g. water in this case) to the reactor is advantageous as it allows to enhance the reaction kinetics, and to maintain a constant volume in the reactor by compensating the permeate flux. Such beneficial substrate addition was demonstrated by Ma et al. , which conducted the membrane-assisted enzymatic protein hydrolysis for the tailored production of antihypertensive peptides. First, the membrane ultrafiltration unit was implemented at the outlet of the reactor tank, which allowed to recycle the free enzymes (retained in the retentate) and prevent undesired product inhibition (via product separation). When further coupling the enzymatic hydrolysis (performed in recirculating mode) with continuous feeding of water to the reactor, the yield and productivity were respectively enhanced by 62.7% and 22.1% when compared to the standard batch operation (i.e. run without membrane separation and substrate feeding). The continuous addition of the protein substrate (in addition to water feeding) enabled to further boost the peptides productivity.