Profound changes of mitochondria during postmortem condition used as freshness indicator in grass carp (Ctenopharyngodon idella) muscle

Flesh quality changes during postmortem condition are involved with apoptosis initiation. Therefore, flesh quality evaluation based on the alteration of apoptosis process is quite important. Mitochondria, the regulation place of apoptosis, undergo profound changes in fish muscle during postmortem. Thus, this study aimed to investigate whether mitochondrial related parameters during apoptosis process constitutes a putative early fish freshness marker. Mitochondrial profound impairments during postmortem at 4 °C for 5 days demonstrated that the structural changes [double layer membranes and cristae, volume, swelling, membrane potential (ΔΨm), MPTP opening and membrane fluidity] and dysfunctional changes [energy deficiency and disharmony of Ca2+ homeostasis] were occurred during postmortem alteration for energy deficiency and the oxidation by ROS accumulation. Study also investigated energy metabolism related products, TVB-N, lipid and protein oxidation. Compared with the insignificantly increased traditional freshness indicators (except K value) at the initial stage (day 1), the most sensitive parameters based on mitochondrial impairment were [mitochondrial swelling, depolarization of ΔΨm, and membrane fluidity]. Therefore, these above parameters might be considered as suitable and early indicators for freshness evaluation.