A study was made to clarify the polymerization and degradation profile of myofibrillar proteins in the salt-ground
meats during heat-induced gelation process of Pacific whiting frozen surimi and the effects of bovine plasma protein on it.
Frozen surimi was thawed and ground with 2.5％ NaCl in the presence and absence of bovine plasma powder (0.5～10.
0%). The salt-ground meats preheated at a fixed temperature in the range of 20 to 60゜C for 2～34 hours were subjected to
subsequent heating at 90゜C for 20 minutes.The subunit composition of myofibrillar proteins in the gels was analyzed using
SDS-polyacrylamide gel electrophoresis. When the salt-ground meats were preheated at 30～40゜C, myosin heavy chain
(HC)in the gels slightly decreased with the production of its polymer, while at 50゜C and over, HC was degraded to the
unidentified components with lower molecular weight,namely X1 and X2,which were postulated to be limited degradation
products of HC.The subsequent heating at 90゜C markedly increased the production of X1 and X2 with the decrease in HC
and its polymer in the preheated gel.Bovine plasma powder suppressed the polymerization and degradation of HC during
the heating process of salt-ground meats, and the suppressive effects was concentration dependent of the plasma powder
added.
Considering the gelation profile of the Pacific whiting frozen surimi introduced in our previous paper (Kato et. al.,
2003), bovine plasma protein was presumed to reinforce the gelation of myofibrillar proteins in the salt-ground meat
through the inhibition of the production of the X1 and X2 from HC as well as the heat-induced gelation of bovine plasma
protein itself at higher temperature.