Long-term suppression of suwari phenomenon for improvement in the manufacturing process of surimi gel product

Surimi gelation at < 40 °C is termed "suwari". Unintentional suwari during the blending and shaping processes (before heating) in the manufacturing of surimi gel products causes serious challenges, because of imperfect molding and clogging in machines. To solve them, effects of transglutaminase and protease inhibitors on suwari gelation properties of Alaska pollock surimi were investigated at 25 °C. Furthermore, thermal gelation properties of surimi after the suwari suppression were studied for preparing gel products with superior physical properties. A 1.0 g/100 g N-ethylmaleimide (NEM) or ethylene glycol tetraacetic acid (EGTA) significantly suppressed suwari at 25 °C for 24 h. The surimi gel with 1.0 g/100 g NEM exhibited superior breaking properties, whereas those of the gel with 1.0 g/100 g EGTA deteriorated upon suwari suppression followed by heating at 90 °C. Adding 10 μmol/L cysteine protease inhibitors, such as NEM or E−64, suppressed the peptide generation in surimi at 25 °C (1.7–2.5 μg/mL) compared to that in the control sample (12.2 μg/mL). Therefore, the inhibition of both transglutaminase and cysteine protease activities was essential for prolonged suppression of the suwari phenomenon and obtaining the heat-induced surimi gel with superior physical properties after the long-term suwari suppression.