Effects of Suwari Suppression and Enzyme Inhibitors on Water Holding Capacity of Alaska Pollock (Theragra chalcogramma) Surimi Gel and Its Improvement by Modified Grinding Method

The processes before heating in surimi gel production, such as grinding and molding, are performed below 10 °C to prevent unintentional protein gelation (suwari or setting) catalyzed by endogenous transglutaminase. Adding transglutaminase and protease inhibitors contributes to obtaining surimi gel with superior breaking properties after suwari suppression. However, the impact of suwari suppression and enzyme inhibitors on the water holding capacity (WHC) of surimi gel remains unclear. This study investigated changes in the WHC of surimi gel during long-term suwari suppression by adding enzyme inhibitors at 25 °C and clarified its mechanism. The expressible drip of samples with EGTA, a transglutaminase inhibitor, increased with heating time at 25 °C to 12.3% owing to proteolysis. The use of N-ethylmaleimide and E-64, cysteine protease inhibitors, further increased the expressible drip of samples (18.9–19.4%) because of protein conformational changes which were observed by DSC analysis and salt solubility measurement. However, this increase was inhibited by a modified grinding method where NaCl was mixed with surimi before adding enzyme inhibitors. This modified method prevented the reduction in protein salt solubility due to protein conformational changes, thereby maintaining WHC in surimi gel with suwari suppression.