不同系统对养殖水体和罗非鱼肌肉异味物质含量的影响

发布时间：2018-08-19 11:25

【摘要】：我国的罗非鱼养殖生产以静水、不排污的池塘养殖为主,鱼类的活动、摄食、排泄都在同一池塘中进行。由于养殖环境和自身生活习性等原因,罗非鱼体内易积累较强的土腥味而不被消费者接受,从而阻碍了罗非鱼养殖和加工的进一步发展。水体中大多数土腥味问题由蓝藻造成的,尤其是在富营养化养殖池塘中。养殖生物粪便和残饵排入水体中,导致水中营养物浓度增大,这为产生异味的蓝藻生长提供条件。所以控制池塘养分供应成为关键。底排污技术可以排除池底的残饵粪便,从源头降低水中营养浓度。水生植物常用于吸收池塘中的无机营养盐,从而限制浮游植物的生长。因此,本论文于2015年通过在广东和海南实地采样初步判断不同系统对罗非鱼肌肉异味物质含量的影响,然后于2016年通过模拟化养殖,运用底排污和“鱼菜共生”技术的整合验证分析其对罗非鱼养殖的水质、产出效果及土腥味物质含量的影响,以探究不同养殖系统对降低罗非鱼肉中异味物质含量的可行性,从而为优化罗非鱼的养殖模式提供科学依据。主要研究结果如下:1.采用微波蒸馏-吹扫捕集-气相色谱-质谱联用方法分析罗非鱼肉中主要的土腥味物质——土臭素(geosmin,GSM)和二甲基异莰醇(2-methylisoborneol,2-MIB),优化了测定其含量的微波蒸馏功率、微波蒸馏时间以及吹扫捕集条件等参数。结果发现:在微波功率560W(仪器额定功率的70%)、微波时间5min、分流比3:1、吹扫时间11min、吹扫温度75℃、含盐量20%条件下,土臭素和2-甲基异莰醇的检测限分别达到了2.89ng/L和2.28ng/L,均在0.05-20μg/L范围内呈较好的线性关系,相关系数r分别为0.9980和0.9985,回收率在81-112%之间,RSD范围在1.8%-12.9%。说明该方法具有较高的精确度。2.为初步判断不同罗非鱼养殖系统下水体和罗非鱼肌肉中异味物质含量的变化,本研究于2015年5月、6月和7月,对我国广东茂名和海南文昌地区4家有底部排污和“鱼菜共生”养殖系统的罗非鱼进行现场采样,结果发现:与对照相比,广东茂名地区和海南文昌地区不同养殖系统会对水体和罗非鱼肌肉中异味物质含量造成影响,配备底排污系统和鱼菜共生系统的池塘异味含量显著低于对照组(P0.05)。3.为了验证不同罗非鱼养殖系统下水体和罗非鱼肌肉中异味物质含量变化,本研究于2016年6月、7月和8月期间,对不同养殖系统的水质变化、罗非鱼产出效果及养殖水体和罗非鱼肌肉异味物质含量变化比较研究。结果发现:对照组、鱼菜共生系统、底排污系统、底排污-鱼菜共生系统四种养殖系统下,以鱼菜共生系统、底排污-鱼菜共生系统罗非鱼产量最高,分别为4.31±0.13kg/m3和4.14±0.09kg/m3,显著高于对照组以及底排污系统(P0.05)。底排污-鱼菜共生双系统对水体的水质情况改善良好,氨氮和亚硝酸含量都在较低的水平(分别为0.64±0.06mg/L和0.086±0.005mg/L),而底排污系统与鱼菜共生系统单独对水质并无明显改变(P0.05)。而养殖系统的不同对水体内的异味物质含量造成影响,配备底排污系统或者鱼菜共生系统的池塘水体异味物质含量明显低于对照组(P0.05)。此外,养殖系统的不同影响了罗非鱼鱼肉中异味物质的含量,且底排污-鱼菜共生双系统作用更明显:对照组罗非鱼肌肉中2-MIB和GSM最高达到0.67±0.022μg/kg和0.87±0.018μg/kg,达到了人体感官阈值水平;而双系统罗非鱼肌肉中2-MIB和GSM最高为0.31±0.02μg/kg和0.53±0.042μg/kg,在各时期均低于另外三组的异味物质含量。
[Abstract]:Tilapia culture and production in China are mainly carried out in still water and non-polluted ponds. Fish activities, feeding and excretion are all carried out in the same pond. Most of the foul smells in the water are caused by cyanobacteria, especially in eutrophic ponds. The nutrient concentration in the water increases when the manure and bait of cultured organisms are discharged into the pond, which provides the conditions for the growth of odorous cyanobacteria. Therefore, controlling nutrient supply in the pond is the key. Bottom drainage technology can eliminate the bottom of the pond. Aquatic plants are often used to absorb inorganic nutrients in ponds, thereby limiting the growth of phytoplankton. Therefore, in this paper, the effects of different systems on muscle odor content of tilapia were preliminarily determined by field sampling in Guangdong and Hainan in 2015, and then simulated in 2016. In order to explore the feasibility of different culture systems to reduce the content of odor substances in Tilapia meat and provide scientific basis for optimizing tilapia culture mode, the effects of bottom sewage and fish-vegetable symbiosis on Tilapia aquaculture water quality, yield and the content of odor substances were analyzed. The results are as follows: 1. Microwave distillation-purge-trap-gas chromatography-mass spectrometry was used to analyze the main odor compounds in tilapia meat, including Geosmin (GSM) and dimethylisoborneol (2-MIB). The power of microwave distillation, time of microwave distillation and purge-trap conditions were optimized. The results showed that under the conditions of 560 W microwave power (70% of the rated power of the instrument), 5 min microwave time, 3:1 shunt ratio, 11 min sweeping time, 75 C sweeping temperature and 20% salt content, the detection limits of soil odor and 2-methylisocamptol reached 2.89ng/L and 2.28ng/L respectively, and the correlation coefficients were 0.05-20 ng/L, respectively. 9980 and 0.9985, with recoveries ranging from 81% to 112% and RSD ranging from 1.8% to 12.9%. This method has high accuracy. 2. In order to preliminarily determine the variation of odor content in water and muscle of tilapia under different tilapia culture systems, the bottom discharges were made in May, June and July, 2015 in Maoming, Guangdong Province and Wenchang, Hainan Province. The results showed that different culture systems in Maoming, Guangdong and Wenchang, Hainan, affected the content of odor substances in water and muscle of tilapia, and the content of odor in ponds equipped with bottom sewage system and fish-vegetable symbiosis system was significantly lower than that in control. In order to verify the changes of odor substances in water and muscle of tilapia under different tilapia culture systems, the water quality changes, tilapia production effects, and the contents of odor substances in cultured water and muscle of tilapia were compared between June, July and August, 2016. The yield of tilapia in fish-vegetable symbiosis system, bottom sewage system and bottom sewage-fish-vegetable symbiosis system was the highest, which were 4.31 (+ 0.13kg/m3) and 4.14 (+ 0.09kg/m3) respectively, significantly higher than that in the control group and bottom sewage system (P 0.05). The yield of tilapia in bottom sewage-fish-vegetable symbiosis system and bottom sewage-fish-vegetable symbiosis system was the highest. The ammonia nitrogen and nitrite contents were low (0.64 The content of odor substances in the pond water of the living system was significantly lower than that of the control group (P 0.05). In addition, the different culture systems affected the content of odor substances in the meat of tilapia, and the effect of the bottom sewage-fish-vegetable symbiosis system was more obvious. The highest level of 2-MIB and GSM in the muscle of tilapia in the control group was 0.67+0.022 ug/kg and 0.87+0.018 ug/kg, reaching human level. The highest levels of 2-MIB and GSM in the muscle of two-system tilapia were 0.31 (+ 0.02) and 0.53 (+ 0.042) ug/kg, which were lower than those of the other three groups at all stages.
【学位授予单位】：上海海洋大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S965.125;TS254.1

【参考文献】