ATP and Creatine Phosphate Breakdown in Spiked Plaice Muscle during Storage, and Activities of Some Enzymes Involved

Estimating Postmortem Interval by Bioluminescent Determination of ATP Content in the Muscle of Olive Flounder ( Paralichthys olivaceus)

HIGHLIGHTS

ATP content was determined by a luminometer for PMI of sliced raw fish within 24 h. Comparison of RLU by luminometer and HPLC-based ATP content had a high correlation of r² = 0.96 to 0.98. 0.5 M phosphate buffer (pH 6.8) was selected as the optimal buffer for ATP extraction.

Post-mortem Changes in Farmed Spotted Babylon Snail (Babylonia areolata) During Iced Storage

Post-mortem changes in farmed spotted Babylon snail stored in ice for 7 days were evaluated using nucleotide degradation products, K-value, total volatile base nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), organic acid, free amino acids and biogenic amines. During a 7-day ice storage, K-value, TVB-N, TMA-N and organic acids contents increased with increasing storage time (p < 0.05). Changes in free amino acid, such as aspartic acid, serine, glutamic acid, glycine, arginine and proline were observed throughout the ice storage (p < 0.05), while total free amino acids were found to decrease significantly (p < 0.05). Biogenic amines found in snail muscle during ice storage were tyramine, putrescine, cadaverine, agmatine and histamine. Bacteria counts of snail muscle exceeded 7 log CFU/g, which was considered as the limit for acceptability after 7 days of iced storage. This result initiates the use of ice storage as a preliminary treatment for snails transported from farms.

Trends in Postmortem Aging in Fish: Understanding of Proteolysis and Disorganization of the Myofibrillar Structure

Postmortem tenderization is caused by enzymatic degradation of key structural proteins in myofibrils as well as in extracellular matrix, and of proteins involved in intermyofibrillar linkages and linkages between myofibrils and the sarcolemma. The function of these proteins is to maintain the structural integrity of myofibrils. Current data indicate that calpains and cathepsins may be responsible for degradation of these proteins. Other phenomena occurring in cells postmortem (pH drop, sarcoplasmic Ca2+ increase, osmotic pressure rise, oxidative processes) may act in synergy with proteases. Our understanding of the underlying mechanisms of muscle degradation should be improved for an accurate evaluation of the postmortem muscle changes and consequently of the fish quality.