The main purpose of this study was to explore the effects of different bleeding methods on the bleeding effect and fish quality of silver carp. Silver carp is one of the important farmed fish species in China, with efficient filter feeding and a rapid growth rate. The bleeding treatment of silver carp is a key factor affecting its fish quality and freshness. Different bleeding methods will lead to different bleeding effects and fish meat quality. In this study, four bleeding methods were used to treat silver carp, namely head knocking (control group), gill cutting, spine breaking, and tail cutting. This study evaluated the bloodletting effect and fish quality of silver carp after bleeding. The evaluation indicators of the bloodletting effect include operation time, color, hemoglobin (Hb) content, myoglobin (Mb), and metmyoglobin (met-Mb) content. The evaluation indicators of fish quality include thiobarbituric acid (TBA), volatile basic nitrogen (TVB-N), pH, and centrifugal water loss rate under 4°C storage conditions. The results show that compared with the control group and other bleeding methods, the operation of silver carp with tail cutting and bleeding is more convenient and faster, and the bleeding time is the shortest; in terms of color, the silver carp meat with tail cutting and bleeding has significantly higher brightness (L), yellow color degree (b) and whiteness, indicating that its color is brighter; in terms of blood components, the content of Hb and Mb in the meat of silver carp with cut tail and bleeding is the lowest, indicating that its bleeding effect is the best; in terms of fish quality, the cutback and tail cut silver carp have the lowest content. Bleeding silver carp can reduce the growth rate of TBA and centrifugal water loss rate, indicating that it has strong antioxidant and water retention capacity; different bleeding methods have little effect on TVB-N of silver carp, indicating that it has no spoilage degree of fish meat. Significant difference: the pH value of silver carp meat with tail cutting and bleeding is more convenient and faster, and the bleeding time is the shortest; in terms of color, the silver carp meat with tail cutting and bleeding has significantly higher brightness (L), yellow color degree (b) and whiteness, indicating that its color is brighter; in terms of blood components, the content of Hb and Mb in the meat of silver carp with cut tail and bleeding is the lowest, indicating that its bleeding effect is the best; in terms of fish quality, the cut back and tail cut silver carp have the lowest content. Bleeding silver carp can reduce the growth rate of TBA and centrifugal water loss rate, indicating that it has strong antioxidant and water retention capacity; different bleeding methods have little effect on TVB-N of silver carp, indicating that it has no spoilage degree of fish meat. Significant difference: the pH value of silver carp meat with a broken spine and tail cut and bleeding was higher, indicating that the freshness of the fish meat was higher. This study shows that according to the bleeding effect and fish quality indicators, silver carp with tail cuts and blood bleeding have better bleeding effects and improved fish quality, which provides a theoretical basis for mechanical bleeding of silver carp in the future.
To investigate the effects of different bloodletting methods on the bloodletting effect and fish quality of bighead carp, bighead carp were bloodleted by four operation methods, namely, knocking the head to stun (control group), cutting the gills, breaking the spine and cutting the tail, and the effect of bloodletting was evaluated by the indexes of operation time, color, hemoglobin (Hb) content, myoglobin (Mb) and myoglobin with high iron (met-Mb) content; the quality of fish meat was evaluated by thiobarbituric acid (TBA), volatile salt base nitrogen (TVB-N), pH and centrifugal loss rate under the storage condition at 4°C. The quality of fish was evaluated by thiobarbituric acid (TBA), volatile salt base nitrogen (TVB-N), pH, and centrifugal loss rate under 4°C storage condition. The results showed that, compared with other bloodletting methods, tail-cutting bloodletting was easier to operate, and the values of brightness (L), yellowness (b), and whiteness were significantly increased, and the contents of Hb and Mb were low; the growth rate of TBA and centrifugal loss rate could be slowed down by spine-breaking and tail-cutting bloodletting; the different bloodletting methods did not have a great effect on the TVB-N of fish; and the pH of the fish was higher in the spine-breaking and tail-cutting bloodletting, compared with the other experimental groups. The study showed that, based on the bleeding effect and fish quality indexes, the bighead carp with tail-cutting bloodletting treatment obtained better bleeding effects and improved fish quality, which can provide a theoretical basis for future mechanical bloodletting of bighead carp.
