Contribution of sarcoplasmic proteins to myofibrillar proteins gelation

Surimi, a refined protein extract, is produced by solubilizing myofibrillar proteins during the comminuting and salting stages of manufacturing. The resulting paste gels on heating to produce kamaboko or a range of analog shellfish such as crab claw, filament sticks, fish mushroom, and so on. The myosin molecule is the major myofibrillar protein in gelation. It is believed that washing steps during the traditional surimi process play an important role in enhancing the gel properties of the resultant kamaboko by removing water-soluble (sarcoplasmic, Sp-P) proteins. By contrast, some researchers claim that retaining Sp-P or adding it into the surimi gel network not only does not interfere with the action of myofibrillar proteins during the sol-gel transition step but also improves the gel characteristics of the resultant kamaboko. It seems that retention of Sp-P or their addition into raw surimi does enhance the textural properties of kamaboko gel perhaps by functioning as a proteinase inhibitor, particularly against trypsin and trypsin-like proteinases but this depends on the type of applied surimi process. Among different types of Sp-P, it has been claimed that some proteins such as endogenous transglutaminase (TGase) play a more important role than other Sp-P in bond formation, by catalyzing the cross-linking of myosin heavy chain (MHC) molecules during low-temperature setting of surimi, resulting a more elastic kamaboko gel.