TABLE 4.

Heat (56°C)-survival-parameter estimates for L. monocytogenes cells previously incubated at 37°C for 45 min and then held at 4°C for 48 or 144 h in TPB at pH 7.3, 10.0, or 11.0

Storage time (h)	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
48	7.3	1				0.739 ± 0.022	0.989	3.98
	10.0	1				0.473 ± 0.006	0.997	6.22
	11.0	2	0.0001	0.263 ± 0.034	4.170 ± 0.573		0.961	11.20
144	7.3	1				0.795 ± 0.040	0.968	3.70
	10.0	1				0.547 ± 0.021	0.981	5.37
	11.0	2	0.005	0.343 ± 0.036	4.840 ± 0.774		0.974	8.57

^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.