National Research Council of Canada. NRC Institute for Marine Biosciences
neutral red assay; stress response; post-harvest condition
The neutral red assay (NRA) was evaluated and used as a biochemical indicator of stress response in cultured mussels that were subjected to various post-harvest processing and storage conditions. The NRA, which measures retention time of neutral red dye in the hemocyte organelle, the lysosome, can be correlated to the condition of mussels under various circumstances. Shelf life also provides an index of mussel condition and quality. The objectives of this study were to evaluate mussel stress response in relation to post-harvest conditions of (1) handling, (2) processing, and (3) storage practices. Neutral red retention was altered in mussels that underwent washing and declumping compared to unprocessed mussels. However, the process of debyssing substantially decreased neutral red retention in mussels. Mussels held under chilled or iced storage conditions displayed decreased neutral red retention compared to those held under wet storage. The results demonstrated that NRA was a useful index of physiological stress response in mussels subjected to conditions under various culture practices. The implications of this study for growers are that the practice of reimmersion of mussels for 24 h, especially after debyssing, and storage of mussels in water or on ice can reduce stress response and provide a better quality product with longer shelf life.