Recovery of bioactive compounds, such as proteolytic enzymes, from waste streams is a means to both recuperate value and reduce environmental pollution. Previously optimized lab-scale parameters for the recovery of a stable crude protease fraction from Pacific whiting (Merluccius productus) surimi wash water were tested using pilot plant equipment. Pretreatment of surimi wash water with 60 degrees C heat, acidification to pH 6, and centrifugation doubled ultrafiltration membrane flux and significantly improved protease purity by reducing a majority of the 35-205 kDa proteins. Concentrated crude protease obtained from wash water contained predominantly cathepsin L activity. Enzyme purity was increased about 100-fold, and yield was approximately 80%. Stability (frozen and freeze-dried protease) was maintained for 9 weeks at -80 degrees C. Freeze-dried preparations were also stable for 9 weeks at 4 and -15 degrees C. Successful application of pilot plant conditions allows for sufficient production of protease for further investigations into their applicability.