From texture to structure: The key role of caspase-3 on grass carp myofibrillar protein during postmortem storage

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The integrity of myofibrillar proteins during the initial post-mortem storage phase critically determines the shelf-life of fish, profoundly affecting consumer acceptance and market value. This research investigates the degradation of grass carp muscle texture and structure triggered by caspase-3-induced apoptosis, a key factor influencing early storage quality deterioration. By inhibiting endogenous caspase-3, the study tracks changes in apoptosis levels, muscle texture, microstructural integrity, protein organizational structure, and amino acid profiles. Apoptosis was found to peak between 48 and 72h post-mortem, during which caspase-3 activity led to significant muscle softening. This softening is attributed to disruptions in crucial structural components such as the Z-line and M-line, culminating in extensive degradation of myofibrillar proteins. Furthermore, protein structure modeling demonstrated that caspase-3 cleavage at ASP187 critically destabilizes the α-helix structure, underlining the enzyme's pivotal role in the early post-mortem softening of fish muscle. These insights provide a foundational understanding of the biochemical processes that underpin early quality loss in stored fish, offering potential targets for interventions aimed at enhancing fish storage outcomes and extending shelf life in the aquaculture industry.