循环水净化养殖过程中大口黑鲈生长及肌肉品质变化

Changes in Growth and Muscle Quality of Largemouth Bass(Micropterus salmoides)Reared in Recirculating Aquaculture System

为了探究循环水净化养殖对大口黑鲈形体指标、质构特性、营养成分及土腥味物质的影响,采用质构仪测定鱼肉硬度、弹性、咀嚼性等指标;采用常规生化方法、氨基酸自动分析仪、气相色谱检测鱼肉水分、灰分、粗蛋白、粗脂肪、脂肪酸、氨基酸等成分;采用气相色谱-质谱联用仪结合电子舌对鱼肉的土腥味物质和滋味进行分析。结果显示:鱼体肝体比随着净养时间的延长显著降低;相较于净养前,净养后20d内鱼肉硬度、内聚性、咀嚼性、弹性、胶黏性和黏附性均提高;净养过程中,鱼肉中的粗脂肪含量先上升后下降,水分含量则与之相反,并且净养后15d内鱼肉中粗蛋白、灰分、呈味氨基酸、必需氨基酸、单不饱和脂肪酸含量均提高,其中在5d和15d时脂肪酸中的二十碳五烯酸甲酯和二十二碳六烯酸甲酯之和、ω-3族脂肪酸含量显著升高;鱼肉中水溶性蛋白和非蛋白氮含量均显著升高;随着净养时间延长,肌肉滋味差异增大,土腥味物质含量降低,且从15d开始低于感官阈值。综合考虑净养后大口黑鲈形体指标、肌肉质构、营养成分和土腥味物质各项指标后,建议净养时间为15d。

In order to investigate the effect of a recirculating aquaculture system on the body indexes,texture,nutrient composition and earthy odor substances of largemouth bass(Micropterus salmoides),this study determined texture characteristics of fish meat such as hardness,springiness and chewiness,and used conventional biochemical methods,an amino acid automatic analyzer,and gas chromatography(GC)to detect the contents of moisture,ash,crude protein,crude fat,fatty acids,and amino acids.Meanwhile,gas chromatography-mass spectrometry(GC-MS)and electronic tongue were used to analyze the earthy odor substances and taste of fish meat.The results showed that the ratio of liver to body mass decreased significantly with rearing time;after rearing for up to 20 days,the hardness,cohesiveness,chewiness,springiness,adhesiveness and gumminess of fish meat were improved compared with those before rearing.The crude fat content initially increased and then decreased with rearing time,while the moisture content showed an opposite trend.The contents of protein,ash,flavor amino acids,essential amino acids,and monounsaturated fatty acids in fish meat increased after 15 days of rearing.The contents of sum of eicosapentaenoic acid methyl ester,docosahexaenoic acid methyl ester andω-3 fatty acids significantly increased after 5 and 15 days.In addition,the contents of water-soluble protein and non-protein nitrogen in fish meat also increased significantly;with increasing rearing time,fish meat showed an increase in flavor differences,and the content of earthy odor substances decreased,which was below the sensory threshold from day 15 onward.Taking into account the body indexes,nutrient composition and earthy odor substances of largemouth bass muscle,a rearing period of 15 days in the recirculating water system is recommended.