Rheological Characteristics and Microstructure of Common Carp (Cyprinus carpio) Surimi and Kamaboko Gel

Common carp is cheap and prolific in Australian waters and is regarded as an aquatic environmental pest. In order to add value to this fish species, surimi and kamaboko was prepared from common carp and its rheological and microstructure characteristics were compared with those produced from Alaska pollock and threadfin bream. Temperature sweep tests were run under 100-Pa stress and 0.1-Hz frequency, obtained from linear viscoelastic ranges of all tested fish gels. Storage modulus (G′) thermographs of all samples consisted of two positive peaks and a plateau zone in between. The sol-gel transition was completed at about 53 and 61 °C for these Alaska pollock and threadfin bream gels, respectively, whereas it was recorded at about 69 °C for common carp gel. At these temperatures, G′ of Alaska pollock gel was recorded at 330 kPa, which was 71% and 88% greater than that from threadfin bream and common carp gels, respectively. Furthermore, Alaska pollock and threadfin bream gels had greater gel strength than the gel prepared from common carp surimi. Textural quality could be associated with cross-linking in the gel network. From scanning electron microscopy studies, the microstructure of Alaska pollock gel matrix had about 15,450 polygonal structures per square millimeter with an average area of about 9 μm². For threadfin bream and common carp gels, the polygonal structures were larger and 12% and 39% fewer, respectively, than those of Alaska pollock gel. However, these results cannot be only attributed to the species variation among tested fish as some other factors such as harvest location, physiological state, handling and processing method, etc. were not considered in this study.