Properties of surimi gel as influenced by fish gelatin and microbial transglutaminase

• Addition of fish gelatin in surimi lowered gel strength of surimi gel.
• MTGase could improve gel property of surimi containing gelatin.
• Addition of gelatin and MTGase at proper levels yielded the acceptable surimi gel.

Gel properties of threadfin bream (Nemipterus bleekeri) surimi added with fish gelatin at different levels (0–20% protein substitution) in combination with microbial transglutaminase (MTGase) at various concentrations (0–1.2 units g−1 surimi) were studied. Breaking force and deformation of surimi gel decreased when the levels of fish gelatin increased (p<0.05). When MTGase was incorporated, the increases in breaking force and deformation were obtained in surimi gel added with 0–15% fish gelatin. Nevertheless, the addition of MTGase at higher levels led to the decrease in both breaking force and deformation of surimi gel containing 20% fish gelatin (p<0.05). Addition of fish gelatin could lower the expressible moisture content of surimi gel. Band intensity of myosin heavy chain (MHC) and actin of surimi gel decreased when fish gelatin levels increased, mainly due to dilution effect. The coarser and irregular gel structure was obtained when fish gelatin was added. The addition of 1.2 units MTGase g−1 surimi decreased MHC in surimi gel containing fish gelatin slightly.