Modori reaction in blue grenadier and Alaska pollock frozen surimi and myosin degradation behavior upon addition of protease inhibitors

The changes in protein degradation behavior in fish surimi upon addition of different protease inhibitors were examined, with the aim of identifying the proteases involved in the modori reaction in different species and grades of fish and at different temperatures.

The modori reactions at 40, 50, and 60°C in four frozen surimi samples: grades FA and KA blue grenadier and grades SA and RA Alaska pollock were investigated. In the grade FA blue grenadier surimi, the modori reaction primarily involved metalloproteases at 40°C, serine proteases and cysteine proteases at 50°C, and cysteine proteases at 60°C. The reaction in the grade KA blue grenadier surimi involved multiple proteases at 40°C, and metalloproteases and cysteine proteases at 50 and 60°C. In the Alaska pollock surimi, multiple proteases were suggested to be equally involved in the modori reaction at 40, 50, and 60°C in both grades SA and RA samples.