Effects of microbial transglutaminase on gel formation of frozen-stored longtail southern cod (Patagonotothen ramsayi) mince

The effects of addition of microbial transglutaminase (MTGase) on gel forming properties of frozen stored longtail southern cod mince (LSCM) were investigated at different incubation temperatures (35 °C, 40 °C, 45 °C, 50 °C). The results showed that frozen stored LSCM had poor gel-forming ability. With MTGase addition, the gel-forming ability of the LSCM was significantly improved, with the best performance obtained at 35 °C heating for 2 h. MTGase promoted myosin cross-linking, which led to an increase in gel strength. Circular dichroism analysis revealed that the myosin rod went through unfolding in two phases, at 30 °C and 38.5 °C, respectively. At 35 °C, myosin rod was only partially unfolded, with 40% helical structures remained which appeared to play critical roles in promoting intermolecular cross-linking. According to the scanning electron micrographs, the higher connectivity and lower porosity was correlated to the higher gel strength. This study showed that the effect of MTGase could be synergistically combined with proper selection of incubation temperature and time to improve gelation properties of fish mince products. •Microbial transglutaminase improves the gel properties of the frozen fish mince.•The partial unfolding of myosin rod play an important role in gel formation.•Myosin rod structure on the transglutaminase-induced gelation to improve the process.