为探索养殖鱼类冷鲜品的源头“锁鲜”机制及可行性，以养殖红鳍东方鲀为研究对象，离水后分2个阶段进行品质解读，屠宰及死后处置环节为品质易逝期(QDP)，冷藏流通过程为后品质易逝期(P-QDP)，探讨易逝期冷却处置对后易逝期的延迟效应。健康活体离水后立即进行人道致死排血，随即置于−1 °C冰海水中冷却20 min，再经沥水、分割及漂洗等加工处理，产品与碎冰一并装箱进入冰藏；对照组除了不做冷却处置，其他处理条件相同。以僵直指数、pH、乳酸、ATP关联化合物及K值等为指标，对鱼体死后生化代谢变化进行跟踪分析；同时，跟踪肌肉显微结构变化，对肌肉品质进行对照分析。结果显示，①易逝期冷却处置可使鱼体温度在20 min内由10.9 °C迅速降至2.7 °C；由于河鲀加工特殊的强漂洗处置，导致加工后约1 h鱼体温度明显回升至8.5 °C；进入冰藏后12 h左右，2组鱼体温度均下降至0.5 °C左右。②从肌肉显微结构可以明显观察到易逝期冷却处置对后易逝期品质的延迟效应。无论处理组还是对照组，随着冰藏期的延长，均可观察到肌肉细胞逐渐瓦解。值得关注的是，处理组与对照组形成鲜明对比，0 d时，与处理组相比，对照组的细胞结构已显现崩解迹象；冰藏期间，肌原纤维间隙增大，肌质网结构肿胀，肌小节存在不平行排列等现象均比处理组明显；特别是在第4天时，对照组的肌小节碎片化严重，且Z线和I带中断，细胞结构模糊，整体破坏程度比处理组严重。③各项分析结果表明，传统的生化指标分析未能敏锐地检测到2组差异。2组生化代谢速率趋同，僵直进程较为相似，僵直状态均能持续4~5 d，乳酸、pH、核苷酸代谢速率几乎同步，K值相差较小，贮藏至8 d均为15%左右。研究表明，离水后鱼肉存在一个品质易逝期，且对后易逝期的鲜品品质有延迟效应。在易逝期对鱼体进行冷却处置，可延缓肌肉细胞结构瓦解，对鱼肉品质具有明显的“锁鲜”效果，这对提升我国水产品品质，从根本上改善国产水产品品质形象具有重要的参考价值。
Market demand for farmed fish products is growing rapidly, However, not all aquaculture sectors produce the premium quality at end of the market. To produce farmed seafood with consistent optimum quality, solutions of stress minimizing and deterioration delaying are worth studying. To explore mechanism and feasibility of “lock in freshness” of farmed fish chilled products, farmed Takifugu rubripes was taken as raw material. The experiment was performed in two post mortem stages, including a quality determination period (QDP) corresponding to on-site handling and post quality determination period (P-QDP) corresponding to the ice storage. The delayed effect of the QDP chilling treatment on the P-QDP was investigated. On-site handling was carried out using humane slaughter followed by instant bleeding in –1 °C sea water with 20 minutes, gutted and rinsed fish were individually wrapped and stored with flake ice surrounded. Meanwhile, the Control group as chilling-free was compared to the Treatment group with chilling at the QDP. The chilled T. rubripes postmortem biochemical metabolism was measured by rigor index, pH, lactic acid content, ATP and ATP-related compounds and K-Value. Meanwhile, the quality was analyzed by muscle ultrastructural changes in two treatments. Treatment temperature after chilling in quality determination period dropped rapidly from 10.9 to 2.7 °C in 20 minutes, which has a significant effect of chilling. Treatment temperature was increased dramatically from 2.7 to 8.5 °C in 1 hour because of the special strengthening body washing process of T. rubripes after being processed. And the fish temperature was reduced to 0.5 °C after 12 h iced storage. The delayed effect of the QDP chilling treatment on the P-QDP can be clearly observed by the muscle ultrastructure. Regardless of the Treatment or the Control, in subsequent chilling storage, muscle tissue degraded gradually. Notable, distinct difference can be observed between the Treatment and the Control. The phenomenon of cell structure degraded of the Control occurred compared with the Treatment on day 0. And intermyofibrillar spaces increased. Sarcomeres were non-parallel and swollen sarcoplasmic reticulum was obvious. Especially on day 4, sarcomeres were altered significantly, mainly at the Z-line and I-band level disruptions. Structure was obscured and destroyed more significantly than the Treatment. But the results showed that traditional biochemical indicators could not be detected for sensitive difference of the two treatments. The Treatment biochemical metabolism rate kept pace with the Control, which the rigor mortis progression was similar and rigor state was maintained 4-5 days. Lactate acid, pH, nucleotide metabolism rate and K-value had no significant difference, and K-value was 15% in 8th day chilling storage. There was a quality determination period after fish was captured, which had the delayed effect of chilled fish quality in the post quality determination period. The degradation of muscle cell could be prolonged by QDP-chilling, which had significant effect of “lock in freshness” on quality of chilled fish. In this way, the image of seafood quality of domestic fisheries could be improved fundamentally, providing significant practical value in China.