Enzymatic Solubilization of Fish Protein Concentrate in Membrane Reactors

Insoluble fish protein concentrate (FPC) was solubilized by the proteolytic enzyme trypsin in batch, semi‐batch and continuous flow membrane raactors. Parametric studies were carried out on the batch system to determine the effects of temperature, pH, enzyme to substrate ratio, and initial substrate concentration on the kinetics of solubilization. The optimum conditions for the batch process were 50°C and pH 9. Product inhibition was found to be significant. At 40°C, pH 9, an initial substrate concentration of 50 mg/cm 3 , and a trypsin to substrate ratio of 0.001 (w/w), 61 per cent of the initial substrate was solubilized within one hour. In the semi‐batch experiments, the effects of temperature, pH, enzyme to substrate ratio, and prewashing of substrate were investigated. The optimum operating conditions for an initial substrate concentration of 50 mg/cm 3 were 50°C and pH 8.8 with a trypsin to substrate ratio of 0.002 (w/w). After 4 hr of operation under the conditions stated above, 85% of the total amount of initial solid was dissolved. 62% of the initial nitrogen content appeared in the permeate.