The effect of frozen storage on the chemical and gel-forming properties of threadfin bream, bigeye snapper, lizardfish and croaker at
218 8C for up to 6 months was investigated. Muscle proteins underwent denaturation as indicated by a continuous decrease in Ca2þ-ATPase
and solubility in 0.6 M KCl throughout the storage ðP , 0:05Þ: Lizardfish produced higher formaldehyde, compared to other species, leading
to a higher protein aggregation as shown by the considerable loss in solubility. Lipid oxidation during frozen storage occurred to different
extent, depending upon the species. Both breaking force and deformation of surimi gels, produced from frozen fish decreased continuously
with the increasing time of frozen storage ðP , 0:05Þ: Expressible moisture increased, whereas whiteness decreased with the extended
storage ðP , 0:05Þ: The decline in gel-forming ability was associated with the decrease in Ca2þ-ATPase and mainly with formaldehyde
formation. Microstructural study revealed that poor surimi gel matrix was caused by the frozen storage.
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