TABLE 3.

Heat (56°C)-survival-parameter estimates for late-stationary-phase (48-h) L. monocytogenes cells incubated at 37°C for 15 or 45 min in TPB at pH 7.3, 10.0, or 12.0

Treatment time (min)	TPB pH (±0.1)a	Eqn.b	(1 − f) least heat-sensitive fraction	β2 − least heat-sensitive fraction (min−1)	β1 − most heat-sensitive fraction (min−1)	β (min−1)	Pseudo r2c	Logistic D value (min)d
15	7.3	1				0.572 ± 0.025	0.979	5.14
	10.0	1				0.491 ± 0.007	0.998	5.99
	12.0	2	0.2	0.179 ± 0.007	0.542 ± 0.084		0.990	16.42
45	7.3	1				0.533 ± 0.028	0.968	5.52
	10.0	1				0.433 ± 0.011	0.993	6.79
	12.0	2	0.1	0.576 ± 0.021	1.850 ± 0.198		0.996	5.10

^aThe pH of TPB was adjusted using 1.0 N NaOH. 

^bParameter estimates were obtained by fitting survival data to the appropriate logistic equation (Eqn.) by nonlinear regression. 

^cCalculated as 1 − (residual sum of squares/corrected total). 

^dCalculated as D = 2.94/β for equation 1 or D = (ln19)/β₂ for equation 2.