High pressure effects on lipid oxidation in minced pork

Washed muscle fibres and minced pork were subjected to high pressure treatment at 800 MPa for 20 min at 20 °C prior to storage at 4 °C. In both cases, high pressure treated samples oxidised more rapidly than the controls, as measured by 2-thiobarbituric (TBA) number. The rate of lipid oxidation of the high pressure treated samples was similar to that induced by heat (80 °C for 15 min). No significant increased rate of oxidation was observed in minced meat samples treated at 300 MPa but above this pressure the rate increased with intensity. Minced meat samples pressure treated in air had higher initial TBA numbers than those treated in nitrogen, but upon storage both oxidised more rapidly than untreated samples. Differential scanning calorimetry, reflectance spectrophotometry and electrophoresis showed that treatment above 300-400 MPa caused marked denaturation of the myofibrillar and sarcoplasmic proteins and conversion of reduced myoglobin/oxymyoglobin to the denatured ferric form. The possible role of these reactions in catalysing lipid oxidation is discussed.