罗非鱼不同养殖系统对产出效果及异味物质含量的影响

Variations in output and the off-flavor compounds geosmin and 2-methylisoborneol in different tilapia cultivation systems

对鱼菜共生系统、底排污系统、底排污+鱼菜共生3种养殖系统的水质变化和罗非鱼产出效果进行了分析,并利用微波蒸馏-吹扫捕集-气相色谱质谱联用技术检测了各系统水体中和罗非鱼肌肉中异味物质的含量变化。经过12周的养殖实验,对终重、生物量、特定生长率、饵料系数、增重率等指标进行测量比较,结果发现,罗非鱼的产出效果从优到差依次为:鱼菜共生组、底排污+鱼菜共生组、底排污组、对照组;底排污+鱼菜共生系统水体中溶解氧在各时期均最高,其亚硝氮、氨氮含量在各时期均最低;底排污或鱼菜共生系统均能有效降低养殖水体中异味物质2-MIB和GSM含量;对照组罗非鱼肌肉中异味物质含量最高,2-MIB和GSM分别达到(0.67±0.02)μg/kg和(0.870±0.018)μg/kg,而底排污+鱼菜共生组罗非鱼肌肉中异味物质含量在各时期最低,2-MIB和GSM分别为(0.31±0.02)μg/kg和(0.53±0.042)μg/kg。结果表明,在罗非鱼精养池塘中,可通过底排污和鱼菜共生结合,降低水体中和罗非鱼体内异味物质的累积,提高其经济价值。

This study compared the effects of four different tilapia cultivation systems （a tilapia-water spinach in- tegrated system, a sewage discharging system, a sewage discharging and tilapia-water spinach integrated system, and a tilapia monoculture system as a control） on the variations in water quality, tilapia production, and off-flavor contents in water and tilapia in June, July, and August 2016. Using gas chromatography and mass spectrometry （GC-MS） based on microwave-assisted distillation followed by purge-and-trap, the off-flavor compounds geosmin （GSM） and 2-methylisoborneol （2-MIB） were determined in water and tilapia tissue. The results showed that production in the tilapia-water spinach integrated system was the highest among the systems examined （P〈0.05）. The contents of ammonia nitrogen and nitrite in the sewage discharging and tilapia-water spinach integrated system were significantly lower compared with the control group [（0.67±0.02） μg/kg and （0.870±0.018） μg/kg]. In addition, the concentrations of 2-MIB and GSM in the muscle of tilapia in the sewage discharging and tilapia-water spinach integrated system [（0.31±0.02） μg/kg and （0.53：e0.042） μg/kg] were significantly lower than those in the control group [（0.67±0.02）μg/kg and （0.870±0.018） μg/kg, respectively]. These results indicate that the sewage discharging and tilapia-water spinach integrated system reduced the accumulation of off-flavor compounds in water and tilapia muscle in an intensive tilapia farming system.