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

研究了土霉素在日本对虾(22.9±4.9g)体内组织残留的时间过程。这些对虾被饲养在盐度为22-23‰的循环人工海水水箱中。水温调至25℃。将土霉素混合到饲料中，并通过导管口服给对虾。土霉素剂量为50 mg/kg体重。在每个采样时间，四只对虾被宰杀，并对组织进行采样。用高效液相色谱法测定土霉素的浓度。土霉素在血淋巴肌肉和甲壳中的回收率分别为91.7%、87.5%和87.3%。土霉素浓度较高的顺序为贝氏血淋巴≧肌。血淋巴和肌肉的消除半衰期分别为44.7h和46.8h。计算血淋巴和肌肉的消除时间分别为9.9天和9.3天。然而，由于土霉素残留存在于壳体组织中，因此无法计算壳体的消除半衰期和消除时间，而且直到20d才能识别消除相。这表明土霉素在对虾的壳组织中积累。通常的烹饪方法(煮沸、烘焙和油炸)可将肌肉中土霉素残留量降低到50-70%，而贝壳中的残留量仅为20%-30%。这些结果证实了土霉素在壳组织中的热稳定性比在肌肉中更稳定。

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.