Comprehensive Analysis of Physiological, Biochemical and Flavor Characteristics Changes in Crucian carp (<em>Carassius auratus</em>) under Different Concentrations of Eugenol

Abstract

Eugenol is a widely used fishery anaesthetic. This study investigated the effects of various concentrations of eugenol on blood physiological and biochemical indexes, and muscle flavor, in crucian carp (Carassius auratus). To determine the appropriate concentration of eugenol anesthetic for use in crucian carp transportation and production operations, we evaluated seven anaesthesia groups of 20, 30, 40, 50, 60, 70 and 80 mg/L and one control group (without eugenol) to determine the effects on blood physiological and biochemical indexes, and muscle flavor. The red blood cells and platelets of crucian carp decreased significantly (P&lt;0.05) with eugenol treatment. With increasing eugenol concentration, the white blood cells and hemoglobin did not change significantly, whereas lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase increased significantly (P&lt;0.05). The content of phosphorus, magnesium and sodium increased after anaesthesia, whereas the content of potassium decreased with increasing eugenol concentration. After anaesthesia, the content of albumin and total protein in the serum decreased with increasing eugenol concentration (P&lt;0.05); triglyceride first increased and subsequently decreased (P&lt;0.05); blood glucose content first increased and then decreased (P&lt;0.05); and no significant difference was observed in total cholesterol content (P&gt;0.05). No significant difference was observed in muscle glycogen and liver glycogen content after eugenol anaesthesia (P&gt;0.05). The eugenol-based anaesthesia test did not indicate major liver histomorphological effects, but the very small number of gill sheet edema cases observed requires further study. Analysis of electronic nose data indicated that eugenol treatment affected the flavor of the fish. The anaesthesia concentration of 20&ndash;80 mg/L had little effect on the physiology and biochemistry of crucian carp, thus providing a reference for the application of eugenol in crucian carp transportation and experimental research.