Effect of varying high-pressure treatment conditions on acceleration of ripening of cheddar cheese

The effects of high-pressure (HP) treatment conditions on proteolysis in Cheddar cheese ripening were investigated by response surface analysis. A second-order central composite rotatable design (CCRD) was used to study the influences of pressure and processing time in the range 70–400 MPa and 3.5–81.5 h, respectively, at 25 °C. Separate control samples were maintained for equivalent times at 25 or 8 °C at atmospheric pressure. Urea-PAGE analysis indicated that breakdown of αs1-casein, and concomitant production of αs1-I-casein (f 24–199), was increased by treatment at 100 MPa for 70 h at 25 °C. Accumulation of αs1-I-casein did not increase at >225 MPa and, at 350–400 MPa, decreased accumulation of αs1-I-casein was observed. Response surface models indicated that treatment at pressures