Development of an indirect α-actinin-based immunoassay for the evaluation of protein breakdown and quality loss in fish species subjected to different chilling methods

alpha-Actinin release from the myofibrillar protein fraction to the sarcoplasm can be considered as an accurate proteolysis index in seafood muscle. The main objective of the present study was to develop a specific enzyme-linked immunosorbent assay (ELISA), based on the use of a monoclonal antibody against a-actinin to evaluate the degree of proteolysis in two different chilled fish species - European hake (Merluccius merluccius) and turbot (Psetta maxima) - kept under two different storage systems: flake ice and slurry ice. Comparison with sensory assessment, K-value and sarcoplasmic protein profiles was carried out. A different degree of proteolysis could be observed in both fish species; thus, the immunoassay was shown to be useful in monitoring the protein degradation events in hake muscle especially under flake ice storage. In the case of turbot, as very low proteolysis development could be obtained, the assay was not suitable for assessing quality changes. A different break point of imummoassay values for each fish species is suggested.