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ABSTRACT

A proteinase from Pacific whiting surimi wash water (SWW) was recovered by ohmic heating, ultrafiltration, and freeze drying with overall yield of 0.83 g protein/L SWW and 78% recovery of activity. Ohmic heating conditions were optimized for the maximum recovery of the enzyme. Different applied voltages (50, 70, 90 V) showed no differences in efficiency for removing protein and retaining cathepsin Lactivity. Cathepsin L activity reached its maximum after ohmic heating to 55C whereas cathepsin B activity decreased constantly with increased temperature. A constant reduction in protein content was observed with the increase in temperatures from 45C to 60C and holding time up to 5 min. The highest retention of both total and specific activity of cathepsin L was obtained with the treatment at 55C for 3 min. Under these conditions, 193% activity was recovered from SWW although a large amount of the activity was lost by the subsequent steps of ultrafiltration and freeze drying.