Effect of season and fishing ground on the activity of cathepsin B and collagenase in by-products from cod species

Cathepsin B and collagenase are important enzymes in the quality-deteriorating processes of fish products. Fish by-products are the left-overs after preparation of the main product and are highly perishable fractions of the fish. They do, however, contain high-quality protein with a potential for utilization. This study characterizes the activity of cathepsins B and collagenase in by-products from five species of cod caught in different fishing grounds and in different seasons. Mean maximum cathepsin B activity was measured at 35 °C in the viscera and the liver, and 50 °C in cut off, while collagenase showed mean maximum activity at 20 °C in cut off, 35 °C in liver and 50 °C in viscera. Species, season and fishing ground significantly affected activity of cathepsin B and collagenase in cut off samples, while viscera samples were not significantly affected. Cathepsin B was more heat stable than collagenase in all three fractions. Both cathepsin B and collagenase from cut off were less heat stable than the corresponding enzymes from the other two fractions.