Effects of Monovalent Cations on Cross-linking of Myosin in Suwari Gels from Walleye Pollack.

Abstract

Salted pastes prepared from walleye pollack surimi by the addition of one of NaCl, KCl, and NH4Cl were incubated at 25°C to produce suwari gel and then cooked at 90°C for 20 min (cooked gel). It was found that the suwari and cooked gels having strong firmness were produced by the addition of NaCl to above 0.2M with a concomitant formation of cross-linked myosin polymers. The suwari and cooked gels containing KCl in the range of 0.1-0.8M were markedly lower in gel strength and in a degree of myosin cross-linking. The setting of the surimi paste containing KCl was not linked to the final cooked gel strength. The experiment using a fluorescent probe, monodansylcadaverine, for monitoring the TGase action during the setting demonstrated that the action on myosin heavy chains occurred significantly in the presence of NaCl, but not in KCl. Since the activity of crude TGase prepared from the surimi was not affected by the addition of KCl as well as NaCl when the acetylated casein was used as a protein substrate, it seems that reactive sites on myosin molecules will not be accessible to TGase in the presence of KCl. Surimi paste containing NH4Cl did not form suwari gel nor TGase-mediated myosin polymers.