清水池塘吊水饥饿处理对大口黑鲈品质的提升效果

为了研究吊水饥饿处理对土塘养殖大口黑鲈（Micropterus salmoides）鱼肉品质的提升效果，本研究在种植苦草(Vallisneria spiralis)的清水池塘中，比较了不同暂养时间下（0、1、4、7、10、13、16 d），鱼肉的营养成分、质构特性和土腥味物质的变化情况。结果发现，暂养不同时间后：（1）大口黑鲈鱼肉的水分含量显著下降至74.90±2.40%（第7 d），灰分含量显著上升，达到1.27±0.17%（第7 d）；总糖含量先下降，后恢复至初始含量水平0.49±0.03 g/100 g（第13 d）。（2）鱼肉中不饱和脂肪酸新增加3种（C20:3n3、C20:4n3、C22:4n6），总脂肪酸达到23种（第10 d）；游离氨基酸有16种，氨基酸滋味活性值（taste active value，TAV）随着暂养时间延长有显著变化（P<0.05），其中具有鲜味的谷氨酸TAV>1（第4 d），呈苦味的组氨酸TAV<1（第16 d）。（3）暂养10 d后，鱼肉硬度和咀嚼性显著增加（P<0.05）。（4）鱼肉中土腥味物质2-MIB和GSM含量分别由开始的0.42±0.01 μg/Kg和0.54±0.06 μg/Kg下降到0.33±0.05 μg/Kg、0.35±0.06 μg/Kg（第16 d）。本研究表明清水池塘暂养处理能显著改善大口黑鲈的鱼肉品质，综合提升效果和经济效益，暂养时间为10 d较好。

Effect of temporary rearing treatment in clear water pond on the quality improvement of largemouth bass (Micropterus salmoides)

Off-flavor problem commonly exists in traditional aquaculture systems, and it has been reported that a temporary rearing model with clean water could remove the off-flavor in fish effectively. In order to study the effect of temporary rearing on off-flavor depuration and fish quality improvement of largemouth bass (Micropterus salmoides), we have cultured fish in pond with Vallisneria spiralis for different time (0, 1, 4, 7, 10, 13, 16 d). The results showed that: (1) The concentration of 2-methylisoborneol (2-MIB) and Geosmin (GSM) decreased from 0.42±0.01 ug/kg and 0.54±0.06 ug/kg to 0.33±0.05 ug/kg and 0.35±0.06 ug/kg, respectively (10^th day). (2) Moisture of fish muscle was decreased significantly to 74.90±2.40% (7^th day), and ash content was increased significantly to 1.27±0.17% (7^th day). The total sugar content firstly decreased and then recovered to the initial level of 0.49±0.03 g/100 g (13^rd day). (3) Three kinds of unsaturated fatty acids (C20:3N3, C20:4N3 and C22:4N6) were increased, and 23 kinds of total fatty acids were detected in fish (10^th day); there were 16 kinds of free amino acids, and the taste active values (TAV) of amino acids were significantly different through the extension of rearing time (P<0.05), including glutamate (TAV>1) with umami taste and histidine (TAV<1) with bitter taste. (4) After 10 days of temporary rearing, the hardness and chewiness of fish were significantly increased. In conclusion, the temporary rearing in clear water pond planted Vallisneria spiralis could significantly depurate off-flavor and improve the quality of largemouth bass, and a 10-days temporary rearing is benefit for both quality and economic.