Structural changes in natural actomyosin and surimi from ling cod (Ophiodon elongatus) during-frozen storage in the absence or presence of cryoprotectants

Surimi and natural actomyosin (NAM) from ling cod (Ophiodon elongatus) were subjected to frozen storage in the absence or presence of cryoprotectants (sorbitol, sucrose, lactitol, and Litesse, either individually or in combin ation). Effects of frozen storage were studied for NAM frozen at -10 degree sC for 10 days and for surimi after eight freeze-thaw cycles. A commercial blend cryoprotectant (4% sucrose and 4% sorbitol), individual cryoprotectan ts at 8%, and optimal blends at 4, 5.5, 6, and 8%, were effective in mainta ining the gel strength of surimi and NAM gels. Surimi or NAM frozen in the absence of cryoprotectants or with only 4% individual cryoprotectants, show ed increased percent a-helical content by Raman analysis. Increased disulfi de content was also observed in the treatment without cryoprotectants by th e Raman SS stretching band and by chemical determination. Tyrosine residues were in a buried environment before and after freezing for all treatments, and surface hydrophobicity measured by 1-anilinonaphthalene-8-sulfonate de creased after frozen storage in the absence of cryoprotectants.