Study on the effect of Konjac hydrocolloid on physicochemical and textural properties of surimi produced from Talang Queenfish (Scomberoides commersonnianus) and Lizardfish (Saurida tumbil)

Every year during marine fishing, some species that are caught are not suitable for human consumption and they are known as surplus fishing or low consumption, which is an important factor in wasting these rich resources. Therefore, it is necessary to set arrangements to use such species for human consumption, including the production of surimi. The surimi industry mainly uses Alaska pollock fish as the main source for surimi production. However, due to the increase in the world’s population and partly the depletion of the fish stocks, followed by a reduction in the surimi production of Allaska Pollock fish (due to restrictive fishing laws), the need to use new species is considered urgent. In this regard, additives such as gums can be used to reform and improve the properties of surimi. Therefore, in this study, the possibility of producing surimi paste and gel from Lizardfish and Talang Queenfish was investigated and the effect of Konjac on the physicochemical properties of the product produced from these two types of fish was evaluated.

In this study, Talang Queenfish and Lizardfish with approximate weight of 225.9±33.6 and 275.9±24.4 g and average size of 15.1±2.4 and 17.3± 2.6 cm, respectively, were purchased freshly from the fish market. After preparing surimi paste from both types of fish, Konjac gum in concentrations of 0.25, 0.50 and 0.75 % (w/w) was added directly to the surimi paste. Then to prepare surimi gel, first, the samples were placed in a water bath at 25 ° C for 3 hours for setting and then cooked at 90 ° C for 20 minutes. After that, the prepared gels were cooled in iced water immediately. The produced paste and gel were evaluated in terms of chemical composition, water holding capacity and color factors. Texture and sensory characteristic were assessed on the produced gels of both types of fish and compared with the control sample (without gum).

According to the results, the yield of Lizardfish was 28% and Talang Queenfish was 22%. It seems that the larger size of Lizardfish has been effective in its higher yield than Talang Queenfish. Based on the results, the percentage of ash, protein and fat in the treatments did not change significantly compared to the control sample. Also, there was no significant difference between the two types of fish in the amount of mentioned factors (p>0.05). As the contraction level of Konjac gum increased, the amount of moisture and water holding capacity of the paste samples of both fish increased significantly, which is due to the absorption and binding of water by the Konjac hydrocolloid. The lightness level (L*) of the surimi paste and gel of both types of fish increased significantly with the addition of Konjac, which is related to the increase in water content in the samples. The lightness of the surimi paste and gel of Lizardfish was higher than that of Talang Queenfish, which is due to the presence of more pigments in the Talang Queenfish meat. Control Sample and treatment of 0.25% of Talang Queenfish surimi paste showed more yellowness and redness than Lizardfish, but in the resulting gel, their values were reduced, indicating that the formation of gel structure by Konjac gum and binding to the proteins covered the yellowness and redness of the samples. By increasing the concentration of Konjac in surimi gel of both fish the parameters of texture (firmness, cohesiveness, adhesiveness, springiness, chewiness) breaking force and deformation increased significantly compared to the control sample. Also, the results showed that the surimi gel from Lizardfish has higher firmness, cohesiveness and strength than Talang Queenfish. Sensory evaluations showed that the panelists assigned the highest score for the surimi gel from Lizardfish to the 0.5% treatment and for the Talang Queenfish to the 0.75% treatment of Konjac. Based on the findings of the present study, it was found that surimi gel from Talang Queenfish has a lower quality than Lizardfish, but with the addition of Konjac gum, its properties can be improved.