Abstract: The effects of heat treatment temperature (100, 110, and 120 ℃) and duration (15, 30, and 60 min) on the gel properties of proteins extracted from silver carp muscle using isoelectric solubilization precipitation (ISP) and those recovered from surimi wash water including gel strength, water-holding capacity, color, chemical interactions and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) pattern were analyzed and compared. The results showed that that ISP protein gels had weaker breaking force and higher deformation degree than did washed protein gels. The highest gel strength for washed protein gels and ISP protein gels were found under thermal treatments at 110 and 100 ℃, respectively. With increasing treatment time, breaking force and deformation degree decreased for the two protein gels. The water-holding capacity of ISP protein gels was not significantly affected by the treatments, while that of washed protein gels was decreased with increasing heating time. The water-holding capacity, L* value and whiteness of washed protein gels were higher than those of ISP protein gels. With the increase in treatment duration, L* value and whiteness of washed protein gels significantly decreased, while those of ISP protein gels showed an opposite trend. The concentrations of ionic and hydrogen bonds increased first and decreased later, while the concentration of hydrophobic interaction and total sulfydryl group showed a decline trend during the thermal treatment process. With raising temperature and time, the myosin heavy chain (MHC) bands disappeared and the band intensities of actin and myosin light chain gradually decreased in the SDS-PAGE patterns for both protein gels.

Key words: isoelectric solubilization precipitation, surimi gel, high temperature, gel properties