High pressure treatment effects on cod ( Gadus morhua) muscle

After treatment at pressures above 400 MPa, the oxidative stability of the lipids in cod ( Gadus morhua) muscle were markedly decreased as measured by the thiobarbituric acid (TBA) number. This was thought to be due to the release of metal catalysts from complexes, since addition of EDTA effectively inhibited the increased rates of oxidation. As judged by differential scanning calorimetry and electrophoresis this effect did not appear to be related to denaturation of the major proteins in meat, since myosin was denatured at 100–200 MPa and actin and most of the sarcoplasmic proteins at 300 MPa. A few water soluble proteins survived pressures of 800 MPa including several of the proteases, but there was a marked decrease in activity of the neutral proteases (pH optima 6.6) above 200 MPa. In contrast to heat-treatment, pressure was shown to lead to the formation of structures that were stabilised, at least to some extent, by hydrogen bonds and texture profile analysis (TPA) showed that the structures produced by heat and pressure treatments had very different textures.