Abstract
Differences in gel-forming ability of two species of bigeye snapper, P. tayenus and P. macracantus are associated with the differences in some intrinsic properties of muscle. Superior gel-forming ability of P. tayenus to P. macracanthus is attributable to higher thermal stability, higher rate of aggregation via the formation of both hydrophobic interaction and disulfide bonding. In addition, the differences in both extent and molecular properties of endogenous muscle transglutaminase and proteinases between two fish species may be responsible for the differences in gel-forming ability of surimi due to gel setting and gel weakening. Corresponding to the optimum temperatures of crude muscle transglutaminases, P. tayenus and P. macracanthus surimi exhibited optimal setting temperature at 40 and 25°C, respectively. Higher activity of both sarcoplasmic and myofibril-associated proteinases active at elevated temperature of P. macracanthus muscle can lead to higher extent of protein degradation during storage and gel softening during thermal gelation. Deterioration rate of P. tayenus muscle during iced-storage is much slower than P. macracanthus muscle. As a consequence, breaking force of surimi produced from the P. tayenus decrease at a slower rate, compared to that obtained from the P. macracanthus Pretreatment of fish before storage by deheading and evisceration can improve storage stability of fish and slow down the loss of surimi gel quality.
