FIG. 1.

Linear regressions of the loss of CFU during isothermal heating at 55°C (data for AR6) (a) and a temperature scan from 5°C to different temperatures at a heating rate of 10°C/min (b). Circles and dotted line, data for AR6; triangles and solid line, data for DR4. The lines are least-squares regression lines. The reciprocal of the slope in panel a gives the D value (mean values are shown in Table 1). In panel b the slopes and intercepts (means ± standard errors) are as follows: for AR6, 0.365 ± 0.0442°C⁻¹ and −20.54 ± 2.515, respectively; and for DR4, 0.354 ± 0.0358°C⁻¹ and −20.246 ± 2.039, respectively. The corresponding D₅₅ and z values calculated from these slopes and intercepts using equation 1 are as follows: for AR6, 2.5 min and 6.3°C, respectively; and for DR4, 3.4 min and 6.5°C, respectively.