Characteristic gel formation of mixed salt-ground meat from Pacific whiting [Merluccius productus] and walleye pollack [Theragra chalcogramma] and effect of bovine plasma powder added

Characteristic heat-induced gel formation of the mixed frozen surimi from different fish species was investigated in connection with further addition of bovine plasma powder. Frozen surimis of Pacific whiting, walleye pollack and their mixture of various weight ratio were separately ground with 2.5% NaCl or with 2.5% NaCl plus 3% bovine plasma powder. The salt-ground meat was preheated at 30 deg C or 50 deg C for several hours and subsequently heated at 90 deg C for 20 minutes to prepare the preheated gel and the two-step heated gel. The changes in breaking strength (BS), breaking strain (bs), and gel stiffness (GS=BS/bs) of both the heated gels measured as a function of the preheating time. The results obtained were as follows; (1) The BS and the bs of the salt-ground meats from mixed frozen surimi were increased with the progress of preheating at 30 deg C, but markedly degraded by a subsequently heating at 90 deg C for 20 min. Such degradations of the BS also with the bs took place without concerning to the content of Pacific whiting frozen surimi in the mixture. (2) When the mixed frozen surimi was ground with 2.5% NaCl plus 3% plasma powder, the heat-induced gel formation of the salt-ground meat was largely reinforced. The BS and the bs of the two-step heated gel reached to much higher values with the increase in content of walleye pollack frozen surimi in the mixture. (3) There were linear relations between the BS and the GS of both the heated gels formed from the mixed frozen surimi and bovine plasma powder through the preheating at 30 deg C. On the other hand, the BS and the GS of both the heated gels formed from the same material through the preheating at 50 deg C remained in lower, closed values. These results manifested that the salt-ground meat from the mixed frozen surimi from two fish species with bovine plasma powder developed the setting-gel formation, that is the 30 deg C-preheating-time dependent and the following 90 deg C-heating caused additional large increases in the BS value with a slight degradation of the bs value.