Oxytetracycline residues in tissues of kuruma prawn (Penaeus japonicus) and the effect of cooking procedures on the residues

研究了日本对虾（Penaeus japonicus, 22.9±4.9g）组织中土霉素残留量的时间过程。对虾饲养在盐度为22 ~ 23‰的循环人工海水池中。水温调到25℃。将土霉素与饲料混合，并通过导管口服给虾。土霉素剂量为50 mg/kg体重。每次取4只对虾，取组织标本。高效液相色谱法测定土霉素的含量。血淋巴肌和甲壳中土霉素的回收率分别为91.7%、87.5%和87.3%。甲壳血淋巴≥肌肉依次可见高浓度土霉素。血淋巴和肌肉的消除半衰期分别为44.7和46.8小时。血淋巴和肌肉的消除时间分别为9.9和9.3 d。然而，由于土霉素残留在壳组织中，无法计算壳的消除半衰期和消除时间，直到20天才能识别出消除期。结果表明，土霉素在对虾的壳组织中有蓄积。通过通常的烹饪方法（煮沸、烘烤和油炸），肌肉中的土霉素残留量减少到50-70%，而壳中的土霉素残留量仅减少到20-30%。这些结果证实土霉素在壳组织中比在肌肉中更热稳定。

The time course of oxytetracycline tissue residues were studied in the kuruma prawn (Penaeus japonicus, 22.9±4.9g). The prawns were kept in tanks with recirculated artificial seawater at a salinity of 22-23‰. The water temperature was adjusted to 25℃. Oxytetracycline was mixed with the diet and orally administered through a catheter to the prawn. The dose of oxytetracycline was 50 mg/kg body weight. At each sample time four prawns were sacrificed and tissues were sampled. Oxytetracycline levels were determined by high-performance liquid chromatography. The recoveries of oxytetracycline from hemolymph muscle and shell were 91.7, 87.5 and 87.3%, respectively. High concentration of oxytetracycline was observed in the order of shell>hemolymph ≧muscle. The elimination half-lives of hemolymph and muscle were 44.7 and 46.8 hours, respectively. The elimination times of hemolymph and muscle were calculated 9.9 and 9.3 days, respectively. However, the elimination half-lives and elimination time of shell could not be calculated because oxytetracycline residues persisted in shell tissues, and the elimination phase could not be recognized until 20 days. It shows that oxytetracycline accumulates in the shell tissues of prawn. Residual oxytetracycline was reduced to 50-70% in muscle by the usual methods of cooking (boiling, baking and frying), whereas reduced levels in shell were only 20-30%. These results confirm that oxytetracycline is more heat stable in shell tissue than in muscle.