Gelation Characteristics of Surimi Gel from Silver Carp (Hypophthalmichthys molitrix) by Application of Acid-Alkali Processes

Textural characteristics of silver carp surimi gel prepared from acid- and alkali-produced protein isolates were investigated and compared to the surimi gels derived by conventional methods. The acid-aided method showed the most efficiency to recover proteins (86.2%) in comparison to the alkaline-aided (79.8%) and conventional (76.7%) methods. In the washing of fish mince, every step resulted in reduction of sarcoplasmic protein, and consequently the myofibrillar fraction became more concentrated, as shown by the protein patterns in wash water. Some myofibrillar proteins (mainly actin and myosin) were removed along with sarcoplasmic proteins during washing, reducing yield efficiency during the conventional method of making surimi. During the pH shifting process, myosin heavy chain (MHC) was degraded during low (2.5) pH solubilization, whereas there was only a minimal loss of MHC by either hydrolysis or proteolysis during alkaline solubilization. The breaking force and breaking distance of surimi gel prepared in the pH-shifting processes were significantly (p < 0.05) greater than those of surimi gel made by conventional methods, as were expressible moisture, cohesiveness, and springiness. In conclusion, the pH-shifting technique can be considered as an efficient alternative process in recovery of greater quantities of functional protein from silver carp fillet.