Effects of pressurization and refrigerated storage on microstructure of fish muscle tissue

Fish muscle tissues were subjected to high hydrostatic pressures in the range of 1,000-3,000 atm and the tissues subsequently observed using transmission electron microscopy. Pressurization at 1,000 atm caused contraction of the sarcomere with the I-band thin filaments being lost while the A-band was unaffected. On pressurizing the tissues at 2,000 atm, the I-band region became more visible with breakdown of the thin filaments in this region as well as the Z-disks. There was gross disintegration of myofibrillar structure with collapse of A-band structure and T-tubular system on subjecting muscle tissue to 3,000 atm of pressure. However, there were no observable changes in myofibrillar structure beyond these initial changes during the subsequent 21 days of storage under refrigerated conditions (4-7C). The results provide the structural basis for pressure-induced changes in fish texture.