High-pressure/temperature treatment effect on the characteristics of octopus (Octopus vulgaris) arm muscle

Octopus muscle was pressurized at 200, 300 and 400 MPa for 15 min at 7 degr eesC and 40 degreesC: treatments at 400 MPa continuously for 15 min and in three 5 min pulses at 7 degreesC and 40 degreesC were also carried out. Tot al viable counts of Enterobacteriaceae, Staphylococcus aureus and lactic ba cteria, shear strength and autolytic activities were studied. High-pressure treatments reduced colony-forming units (cfu) for all groups tested, espec ially when applied in pulses at 40 degreesC, and caused a change of the pre dominant flora. Autolytic activity clearly decreased when pressure was over 200 MPa. When muscle is pressurized. shear strength increases although it is higher at lower pressures (200 MPa) than at higher pressure (400 MPa). W hen pressure was applied, morphological and ultrastructural changes were ob served, mainly in the variation of fibrillar compacting. destruction of the sarcomere pattern. ultrastructural alteration of the myofibrils and gradua l disappearance of the cell nucleus. The connective tissue was virtually un affected by pressure despite the temperature applied.