Purification and characterisation of transglutaminase from four fish species: Effect of added transglutaminase on the viscoelastic behaviour of fish mince

The transglutaminase (TGase) enzyme from four different fish species, namely bigeye snapper, Indian oil sardine, tilapia and common carp have been isolated and characterised. The specific activity of the enzyme was higher in tilapia followed by oil sardine, common carp and bigeye snapper. The molecular weight of pure TGase was found to be in the range of 73–95 kD for four different fish species. The temperature optima for maximum activity of TGase varied amongst four species studied. The effect of activator (calcium chloride) and inhibitors (ethylenediaminetetraacetic acid (EDTA), ammonium chloride and free lysine–hydrochloride) at different concentrations on the TGase enzyme activity have been evaluated. The addition of isolated TGase to fish mince from Cynoglossus sp. was attempted in order to evaluate the setting and gelling ability. The setting and gelling ability of fish mince in presence of TGase improved considerably as revealed by small strain and large strain test.