Article Figures & Data
Figures
- FIG. 1.
Distributions of detection times estimated directly by optical density measurements in broth inoculated with ca. 1 cell/well and by transforming the log plate counts of detection times in three replicate experiments (R1 to R3).
- FIG. 2.
Distributions of lag times estimated from an unheated and heated dairy product stored at 4°C with a final load of ca. 1 cell per portion.
- FIG. 3.
Distributions of lag times estimated from unheated and heated liver paté stored at 15°C with a final load of ca. 1 cell per portion.
- FIG. 4.
Relationship between natural logarithms of the standard deviation and the mean value of the single-cell lag times estimated for the following groups: preheated cells grown in liver paté stored at 15°C and in a dairy product stored at 4°C, as presented in this paper (•) (a); previously stressed cells grown either in a Bioscreen instrument, as described previously (9 [□] and 14 [▪]), or in a flow chamber, as reported previously (6 [×] and 18 [+]) (b); and healthy cells grown in laboratory media as described previously (11 [▵] and 21 [▴]).
Tables
- TABLE 1.
Means, standard deviations, and P values associated with a χ2 test to compare the distributions of detection times measured by optical densities and estimated from bacterial plate counts in three replicate experiments
Replicate No. of cells/well Techniquea Mean (h) SD (h) P value 1 16 OD 39.14 1.435 0.8887 PC 37.63 0.8191 2 0.70 OD 45.27 1.828 0.4756 PC 41.69 1.811 3 0.88 OD 44.80 1.155 0.8466 PC 47.72 2.531 ↵ a OD, optical density measurement; PC, bacterial plate counts.
- TABLE 2.
Numbers of cells per portion able to grow in paté at 15°C and in a dairy dessert at 4°C in unheated control batches and after different heat treatments
Sample Temp/time (°C/min) No. of cells/portion Liver paté (13-g portions) Unheated 2.4 55/25 0.84 62/1.35 0.64 65/0.33 1.0 Dairy dessert (5-ml portions) Unheated 0.73 55/45 0.60 62/2 4
