【作者】 张瑞霞；

【导师】 熊善柏；

【作者基本信息】 华中农业大学 ， 食品科学， 2008， 硕士

【摘要】 因消费习惯和加工保鲜业发展滞后等原因,我国90%以上的淡水鱼以鲜活形式上市销售,保活运输就成为水产品由养殖基地到销售市场的关键问题。保活运输过程中,各种环境因子都会对鱼体造成胁迫而使鱼体产生应激反应,导致鱼体生理生化的变化,从而影响鱼体的肌肉品质。本试验以鲫鱼为试验材料,在确定了鲫鱼低温处理、MS-222处理和电麻低温相结合的最佳保活条件的基础上,研究低温处理、化学处理及电麻-低温处理对鲫鱼生化特性及肉质的影响。主要研究内容和结果如下:1.研究了低温处理对鲫鱼生化特性及肉质的影响。从20.0℃缓慢降温至3.5℃、6.5℃、9.5℃。在3.5℃、6.5℃、9.5℃和20.0℃4种水温下,鲫鱼的氨氮排泄量随温度升高和暂养时间延长而增大,且20.0℃的氨氮排泄量显著高于其它3种水温的。在4种水温下暂养5d后,鲫鱼的存活率分别为85.0%、100%、94.7%和75.0%,在6.5℃水温下暂养保活效果最好。暂养5d后,对照组(20℃)鲫鱼血液的乳酸脱氢酶、谷草转氨酶、血糖和皮质醇均比试验前高,而低温试验组的鲫鱼均比试验前低。低温处理对鱼肉的弹性、粘附性和粗蛋白含量无影响,而对鱼肉的持水力、回弹性、pH值以及可溶性蛋白含量、粗脂肪含量有显著影响。所以,低温处理对鲫鱼的存活率、生化特性和肉质有明显影响,选择适当的水温(6.5℃)有利于其保活贮运。2.研究了MS-222处理对鲫鱼品质及生化特性的影响。MS-222的浓度、水温以及鱼水比对鱼体血液中的皮质醇、血糖、乳酸脱氢酶和谷草转氨酶有极显著或显著影响。对照组的皮质醇和血糖的含量及乳酸脱氢酶、谷草转氨酶的活性均高于试验前;麻醉组的谷草转氨酶的活性较试验前高,但皮质醇和血糖的含量及乳酸脱氢酶活性的变化不一。MS-222浓度、水温及鱼水比对鱼肉pH值、持水力、粗脂肪含量、粗蛋白含量、可溶性蛋白含量及白度、硬度和粘附性有显著或极显著影响。MS-222浓度为30mg/L,水温为15℃,鱼水比为1:6时,鲫鱼存活率最高,应激反应较弱,肉质较好。3.研究了电麻处理对鲫鱼生化特性及肉质的影响。电麻电压、电麻时间对鱼体皮质醇、血糖、乳酸脱氢酶、谷草转氨酶均有极显著的影响。电麻后,应激反应造成皮质醇、血糖含量和乳酸脱氢酶、谷草转氨酶活性均比电麻前升高。电麻组鲫鱼肉的pH值显著低于未电麻组的,电麻电压或电麻时间对鲫鱼肉的持水力、粗蛋白含量、pH值、可溶性蛋白含量、粗脂肪含量、白度、硬度及回弹性都有极显著或显著影响,对弹性和粘附性没有影响。20V电击6min鱼体应激反应较小,血液生化指标变化较小,营养成分保留相对较高。4.研究了电麻-低温处理对鲫鱼品质及生化特性的影响。采用不同电压或不同时间电麻后直接置于6.5℃暂养5d,电麻组的的皮质醇、血糖、乳酸脱氢酶及谷草转氨酶都低于对照组,电麻后代谢产物氨氮的排泄量明显降低,在后期氨氮量随电压的增大及电麻时间的延长而增加。不同电压或不同时间的电麻对持水力、粗蛋白含量、pH值、可溶性蛋白含量、粗脂肪含量、白度、硬度、弹性、粘附性和回弹性都有极显著或显著影响。20V的电压电击6min并直接置于6.5℃水中暂养5d,鲫鱼存活率最高(91.5%),比对照组高10%,其肌肉的粗蛋白含量、可溶性蛋白含量、粗脂肪含量、弹性、回弹性明显高于未电麻组。更多还原

【Abstract】 There are 90%freshwater fish that are sold lively in China due to some reasons, such as consumption habit,backward development of processing and preservation industry.Transportation of live fish is the key problem which should be solved during transferring aquatic products from farms to markets.Stress responses of fishes are caused by environmental factors,which results in physiologic and biochemical changes of fishes, and finally affected the meat quality.The effects of low-temperature treatment,chemical treatment,treatment combined electrical stunning with low temperature on biochemical indices and meat quality of crucian were investigated,based on the study on the optimum of low-temperature treatment,chemical treatment,treatment combined electrical stunning with low temperature.The results were as follows:1.The effects of low-temperature treatment on biochemical characteristic and meat quality were studied.The results showed that the ammonia-N excretion increased with increasing temperature,and was significantly higher at 20.0℃than three other temperatures(3.5,6.5 and 9.5℃).The survival rates of crucian after holding 5 days were 85.0%,100.0%,94.7%and 75.0%at 3.5,6.5,9.5 and 20.0℃respectively.The optimum temperature for keeping alive was 6.5℃.The contents of LDH,AST,glucose and cortical in the experiment groups(3.5,6.5 and 9.5℃) decreased after holding 5 days, whereas those at 20℃increased.The low-temperature treatment had no significant effects on meat elasticity and the content of crude protein,but had significant effects on water-holding capacity,cohesiveness,resilience,pH value,the contents of soluble protein and fat.The low-temperature treatment had significant effects on survival rate, biochemical characteristic and meat quality,so optimal temperature was 6.5℃for keeping alive during transportation.2.The effects of chemical treatment on biochemical characteristic and meat quality were studied.The effects of MS-222 anesthetic concentration,water temperature and fish density on cortical,glucose,LDH and AST were significant or extremely significant. Cortical,glucose,LDH and AST of the control group were higher than original level. AST of the anesthesia group were significantly higher than original level,but cortical, glucose and LDH of the anesthesia group showed the different trends.The effects of MS-222 anesthetic concentration,water temperature and fish density on pH value, holding-water capability,crude fat,crude protein,soluble protein,whiteness and hardness were significant or extremely significant.When crucian carp was holded at 30mg/L,MS-222 at 15℃with 1:6 fish-water ratio,its survival rate was the highest with lower stress degree and better meat quality.3.The effects of electrical stunning on biochemical characteristics and meat quality were studied.The effects of voltage and time of electrical stunning on cortical,glucose, LDH and AST were extremely significant.Cortical,glucose,LDH and AST increased after electrical stunning,which were caused by stress response.The pH value of the electrical stunning group was significantly lower than that of the control group.Voltage and time of electrical stunning significantly influnced holding-water capability,crude protein,pH value,soluble protein,crude fat,whiteness,hardness and resilience,but had no visible effects on elasticity and adhesiveness.When crucian carp was stunned at 20V for 6min,the stress response was less,with higher retention of nutrition.4.The effects of electrical stunning and low-temperature treatment on biochemical characteristic and meat quality were studied.Crucian carp were directly reared at 6.5℃after stunning with different voltages and time.Cortical,glucose,LDH and AST of the electrical stunning group were lower than those of the control group.The ammonia-N excretion remarkably decreased after electrical stunning.Additionally the ammonia-N excretion increased with increasing voltage and time in the later period.Voltage and time of electrical stunning significantly crude protein,pH value,soluble protein,crude fat, whiteness,hardness,elasticity,adhesiveness and resilience.When crucian carp was stunned at 20V for 4rain or 6min,its survival rate after holding 5 days at 6.5℃were the highest(91.5%),which was 10%higher than that of the control group,meanwhile,its holding-water capability,crude protein,soluble protein,crude fat,elasticity and resilience were higher than that of the control group.更多还原