This study examined the effect of adding common carp sarcoplasmic proteins (Sp-P) on the gel characteristics of threadfin bream surimi and kamaboko while maintaining constant moisture and myofibrillar levels. Based on the temperature sweep test, which is involved in heating of surimi gel from 10 to 80• C to monitor the viscoelastic properties, at temperature range of 40 to 50 • C, the decrease level (depth of valley) in storage modulus (G ) thermograph was in proportion to the concentration of added Sp-P. Storage modulus (G ) showed greater elasticity after adding Sp-P compared with the control without Sp-P. Furthermore, the breaking force and distance and consequently gel strength of the resultant kamaboko were improved significantly (P > 0.05). Thus, added Sp-P did not interfere with myofibrillar proteins during sol-gel transition phase but associated with textural quality enhancement of resultant kamaboko; however, addition of Sp-P from the dark muscle of the carp decreased the whiteness of the resultant surimi. Furthermore, according to the SEM micrographs, the gel strength could not be associated with either the number of polygonal structures/mm 2 or the area of the polygonal structures in the kamaboko gel microstructure.

No abstract

The demand for surimi and kamaboko is increasing in the world at the same time as the supply of the fish traditionally used has declined. In an effort to increase the range and hence supply of fish used, factors increasing the quality of surimi and kamaboko from common carp were investigated. The best surimi and kamaboko characteristics were produced by a modified conventional method (MCM) rather than traditional method (TM), alkaline-aided method (AAM), and pH modified method (PMM). MCM processing used centrifugation instead of decanting and filtering to optimize dewatering and remove the sarcoplasmic proteins (Sp-P). The temperature sweep test, at the end of sol-gel transition stage (at 75 degrees C), showed significantly (P < 0.05) greater G' for the kamaboko from MCM than that from other methods tested. Furthermore, the greatest and the least gel strengths were obtained with MCM and TM kamaboko, respectively. The protein recovery was about 67%, 74%, 87%, and 92% for TM, AAM, MCM, and PMM, respectively. TM and MCM resulted in the removal of Sp-P as determined by SDS-PAGE. The superiority of MCM kamaboko gel characteristics was supported by scanning electron micrographs (SEM) of the gel, which showed a significantly (P < 0.05) greater number of polygonal structures than for the TM kamaboko, which had the fewest and largest polygonal structures. The pH-shifting methods improved the textural quality of the resultant kamaboko compared with TM. However, a simple modification (centrifugation compared with decanting) by MCM in the surimi process can further improve the quality of the surimi and kamaboko gels. Furthermore, because it removed Sp-P and still preserved gel strength, it suggests that Sp-P are not required for gel strength.

No abstract

The preferred colour for surimi is white, but surimi prepared from light fillets of common carp (Cyprinus carpio) is slightly pink. Hydrogen peroxide (H 2 O 2 ; 1-3% v ⁄ v) with and without sodium tri-polyphosphate (STP; 1-2% w ⁄ v) was added to a sodium carbonate bath (pH 7.0-11.5) resulting in a final pH range of 4.4-10.1 which was injected into carp fillets. After soaking and tumbling for 30 min at 4-10°C, the fillets were evaluated for colour and water holding capacity (WHC). Fillets tumbled with treatment solution with different pH levels (7.0-11.5), but with no H 2 O 2 or STP added, had improved colour with significantly (P < 0.05) higher L* compared with untreated fillets as the control. However, the colour improvement [(L* and colour deviation (DE)] was not significantly different (P > 0.05) within the pH levels (7.0-11.5) trialled. With increasing H 2 O 2 levels (1-3%), fillets became lighter and DE increased significantly (P < 0.05), especially with a 3% H 2 O 2 treatment at pH of 10.5 (adjusted pH before H 2 O 2 addition, actual pH after H 2 O 2 addition was 8.2). The whiteness (L*)3b*) of kamaboko produced from treated (3% H 2 O 2 , pH 10.5) common carp light fillets was not significantly different to that of kamaboko from Alaska pollock and threadfin bream. Treatments combining H 2 O 2 (3%) with STP (1-2%) significantly reduced the L* value obtained in comparison with fillets treated with only H 2 O 2 (3%). Similarly, fillets treated with STP (1%) alone, resulting in lower L* values, irrespective of treatment pH (7.0-11.5). WHC, an indicator of the quality of the fillet texture, increased from 816 g ⁄ kg at pH 7.0 without STP to 841 g ⁄ kg at pH 11.5 with 1% STP. Treatment with H 2 O 2 (without STP) decreased the WHC of the fillets.