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 degreesC 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 degreesC. Freeze-dried preparations were also stable for 9 weeks at 4 and -15 degreesC. Successful application of pilot plant conditions allows for sufficient production of protease for further investigations into their applicability.