Mitochondrial activity as an indicator of fish freshness

Abstract

The current methods used to routinely assess freshness in the fishing industry reflect more a state of spoilage than a state of freshness. Mitochondria, the seat of cellular respiration, undergo profound changes in post mortem tissues. The objective of this study was to demonstrate that mitochondrial activity constitutes a putative early fish freshness marker. The structure of gilthead sea bream (Sparus aurata) muscle tissue was evaluated over time by transmission electron microscopy. Respiration was assessed in mitochondria isolated from sea bream fillets using oxygraphy. Membrane potential (ΔΨ_m) was determined by fluorescence (Rhodamine 123). Mitochondrial activity of fillets stored at +4 °C was studied for 6 days. Changes in mitochondrial cristae structure appeared from Day 3 highlighting the presence of dense granules. ΔΨ_m and mitochondrial activity were significantly disrupted in sea bream fillets after 96 h of storage at +4 °C. Mitochondrial activity constituted a reliable and early indicator of fish freshness.

Keywords: 4-Morpholinepropanesulfonic acid (PubChem CID: 70807); Acetonitrile (PubChem CID: 6342); Adenosine 5′-diphosphate (PubChem CID: 128882); Carbonyl cyanide 3-chlorophenylhydrazone (PubChem CID: 2603); Carboxyatractyloside (PubChem CID: 20055804); Cytochrome c (PubChem CID 16057918); Dimethyl sulfoxide (PubChem CID: 679); Ethylene-bis(oxyethylenenitrilo)tetraacetic acid (PubChem CID: 6207); Fish freshness; Gilthead sea bream (Sparus aurata); Glutamate (PubChem CID: 33032); Glutaraldehyde (PubChem CID: 3485); Magnesium chloride (PubChem CID: 5360315); Malate (PubChem CID: 525); Mitochondrial membrane potential (ΔΨm); Mitochondrial respiration; Osmium tetroxide (PubChem CID: 30318); Potassium chloride (PubChem CID: 4873); Potassium dihydrogen phosphate (PubChem CID: 516951); Rhodamine 123 (PubChem CID: 9929799); Sodium cacodylate (PubChem CID: 2724247); Succinate (PubChem CID 160419); Sucrose (PubChem CID: 5988); Tris (hydroxymethyl)aminomethane (PubChem CID: 6503); Uranyl acetate (PubChem CID: 10915).