Characteristic Properties of Heated Gels Formed from Frozen Surimi in Terms of Protein Solubility in Various Solvents and Effect of Addition of Albumen Powder on Gel-formation

Salt (3% NaCl)-ground meats composed of frozen surimi of arabesque greenling (AG) or walleye pollack (WP), both with/without the addition of 3% albumen powder (Al) were heated at 90t for 30 min, both with/without preheating at 25t for different periods. The heated gels were solubilized in various solvents by stirring for 48 hours. Protein solubility was determined and discussed in relation to the rheological properties of the heated gels. (1) Large amounts of protein in the unset gels (directly heated gels from AG/WP and two-step heated gels from AG, both with/without Al) were solubilized in a solvent containing 0.6 M NaCl + 8.0 M urea + 2% mercaptoethanol (2) The protein solubility of the set gels (two-step heated gel from WP, both with/without Al) in solvents containing 0.6M NaCl + 1.5 M urea, 0.6M NaCl + 8.0 M urea, and 0.6M NaCl+ 8.0 M urea + 2 % mercaptoethanol decreased greatly and insoluble proteins accumulated in the gel structure with the progress of preheating. (3) The rate of protein solubility suggested that hydrophobic interaction was strongly related to the rheological properties of the unset gels (and S-S bonding was slightly associated with the addition of Al), whereas a more intensive bonding/interaction was predominantly involved in that of the set gels.