Kinetic analysis of Escherichia coli inactivation by high hydrostatic pressure in broth and foods

High hydrostatic pressure (HHP) inactivation kinetics of Escherichia coli in broth, milk, peach juice and orange juice were evaluated at a pressure range from 300 to 700 MPa. E coli inactivation followed first-order reaction kinetics. Decimal reduction times (D value) for E coli were 3.94 and 1.35 at 400 and 600 MPa, respectively, in broth. D values were 3.19 and 1.66 min for aerobic bacteria (AB) and E. coli, respectively, in milk at 600 MPa and 0.83 and 0.68 min, respectively, in orange juice. The k values were 0.7219 and 1.3904 min(-1) for AB and E coli, respectively, at 600 MPa in milk. The pressure dependence of the bacteria inactivation rates can be described by DeltaV* and by a "pressure z value". HHP treatment is suitable for inactivation of AB and E coli. Analysis of z values indicated that sensitivity of bacteria to pressure changes was different among tested media. (C) 2003 Elsevier Ltd. All rights reserved.