Table 4.
Confirmation experiments of the mathematical equation describing the concentration of the attached to SS coupons population (Log10 CFU/cm2) of the four-strain L. monocytogenes cocktail as a function of time and temperature. Measured and predicted values of sessile populations (Log10 CFU/cm2) for each individual experiment, together with the bias and accuracy factors of the model, are also shown. The 5th experiment was the one executed under conditions (i.e., 54 h at 30.6 °C) predicted to result in the maximum sessile population (5.65 ± 0.40 Log10 CFU/cm2).
| Experiment | Independent Factors a | Response b | ||
|---|---|---|---|---|
| Incubation Time (h) (Χ1) |
Incubation Temperature (°C) (Χ2) |
Attached Population (Log10 CFU/cm2) | ||
| Measured | Predicted | |||
| 1 | 36 (−0.5) | 26 (0.5) | 5.39 ± 0.14 | 5.05 ± 0.40 |
| 2 | 60 (0.5) | 26 (0.5) | 5.40 ± 0.09 | 5.52 ± 0.40 |
| 3 | 66 (0.75) | 11 (−0.75) | 2.96 ± 0.37 | 3.22 ± 0.40 |
| 4 | 66 (0.75) | 29 (0.75) | 5.58 ± 0.05 | 5.55 ± 0.40 |
| 5 (max) | 54 (0.25) | 30.6 (0.89) | 5.46 ± 0.31 | 5.65 ± 0.40 |
| Factors | ||||
| Bias | 1.01 | |||
| Accuracy | 1.04 | |||
a Codes values are shown in parentheses. b Values are means ± standard deviations.