无水保活条件下团头鲂生理应激及鱼肉品质的变化

为探讨无水保活对团头鲂生理应激和肌肉品质的影响,该文研究了团头鲂无水保活所需的较佳条件,测定了未处理(对照)、无水和恢复3种状态下团头鲂的血液生化以及鱼肉成分、持水力、新鲜度、质构和游离氨基酸等品质指标。结果表明:团头鲂无水保活的较佳生活水温为(14.8±0.2)℃(冬季),以2℃/h降至休眠温度2℃,充氧包装后在2℃无水保活14 h,在当季暂养水温中((14.8±0.2)℃)恢复24 h后存活率为100%;无水保活14 h后,血液中皮质醇和乳酸浓度、谷草转氨酶和谷丙转氨酶活力显著高于未处理(对照)(P0.05),血糖浓度和碱性磷酸酶活性明显低于未处理值(P0.05),当季暂养水温恢复24 h后,基本都恢复至未处理组值,但谷草转氨酶仍明显高于未处理组值(P0.05);低温无水环境对团头鲂鱼肉中蛋白质和脂肪含量、新鲜度和持水力无影响,但鱼肉的硬度和咀嚼性明显下降(P0.05),鱼肉游离氨基酸中丝氨酸(Ser)、谷氨酸(Glu)、甘氨酸(Gly)、缬氨酸(Val)和精氨酸(Arg)等含量显著升高(P0.05),异亮氨酸(Ile)、亮氨酸(Leu)、酪氨酸(Tyr)和苯丙氨酸(Phe)在无水保活过程中无明显变化,当季暂养水温恢复后却显著高于未处理组水平(P0.05)。因此,团头鲂无水保活中产生的应激反应在恢复24 h后基本消除,且无水保活对鱼肉的食用品质影响较小。该研究结果为无水保活在淡水鱼活鱼运输中的应用提供参考。

Change of physiological stress and flesh quality of Megalobrama amblycephala during suitable waterless keep alive conditions

Currently circulation mode of freshwater fish was water transport. Commercial cost and several transportation procedures, including catch, temporary culture, transport shake, loading, unloading and distribution, induced harmful stress in fish, caused injury and even death. Related research showed the loss cost accounted for about 10% of the total cost in China, which was 20 times that in developed countries. Therefore, waterless keep alive transport of freshwater fish was more and more taken seriously. Hibernated temperature, packing method, survival time and survival rate of four seasons fish live in waterless environment were researched in order to investigate the effects of physiological stress and flesh quality of Megalobrama amblycephala during suitable waterless keep alive condition.Fish were examined at different time points: living in normal temperature (control), waterlessly keeping alive for 14 h (waterless) and then recovering in normal temperature for 24 h (recover). Blood biochemical items including cortisol (COR), glucose (GLU) and lactic acid (LAC) concentration, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activity were determinated and flesh quality indicators such as water holding capacity, total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), texture and free amino acids were studied. The results showed: suitable living temperature of Megalobrama amblycephalafor waterless keep alive was (14.8±0.2)℃(at winter), and then dropped (2℃/h) living temperature to 2℃ (hibernated temperature). The hibernated fish were packaged in moist wood-shavings but without added water by plastic bag (120 cm×90 cm) and oxygen-rich atmosphere (80% O2), finally plastic bag was sealed and placed at 2℃ for 14h, survival rate reached 100% after (14.8±0.2)℃ (normal temperature)recovery 24 h. Blood COR and LAC concentration, AST and ALT activity of fish keep alive 14h in waterless were significantly higher than normal level (control) (P<0.05), while blood GLU concentration and ALP activity were significantly lower than normal level (P<0.05). After recovery 24 h, most blood biochemical values returned to normal level, except for blood AST activity was still significantly higher than normal value. Protein and fat content, TVB-N, TBA and the water holding capacity of fish flesh were not influenced in low temperature waterless environment, but the fish flesh hardness and chewiness were significantly decreased (P<0.05). Free amino acids Ser, Glu, Gly, Val and Arg of fish flesh at waterless were significantly higher than normal value (P<0.05), concentrations of Ile, Leu, Tyr, Phe at waterless were not significantly change with normal , however, after recovery 24 h, them were significantly higher than normal (P<0.05). In conclusion, the stress induced by the cold and waterless condition in fish can be eliminated 24 h after recovery, and the changes of fish tasting quality are not significant. The results provide a reference for the application of waterlessly keeping alive in transportation of live freshwater fish.