Table 1.
Microorganism | PUV-treatment [time (s)/distance (cm)] | Viable cell population (log RLU mL−1) | |||
---|---|---|---|---|---|
Lettuce | LDPE | ||||
24 h | 48 h | 24 h | 48 h | ||
E. coli O157:H7 | Control (no PUV) | 4.50 ± 0.34 A | 4.40 ± 0.29 A | 4.53 ± 0.35 A | 4.04 ± 0.30 A |
10 s—4.5 cm | 1.97 ± 0.22 C | 2.35 ± 0.27 B | 0.99 ± 0.17 B | 1.34 ± 0.23 B | |
20 s—4.5 cm | 1.22 ± 0.20 C | 1.74 ± 0.24 C | 0.62 ± 0.15 C | 1.20 ± 0.20 B | |
10 s—8.8 cm | 2.61 ± 0.31 B | 2.65 ± 0.29 B | 1.23 ± 0.24 B | 1.65 ± 0.24 B | |
20 s—8.8 cm | 1.62 ± 0.25 C | 2.04 ± 0.26 B | 0.90 ± 0.16 B | 1.38 ± 0.13 B | |
L. monocytogenes | Control (no PUV) | 4.80 ± 0.35 A | 4.70 ± 0.46 A | 4.96 ± 0.32 A | 4.71 ± 0.36 A |
10 s—4.5 cm | 3.39 ± 0.24 B | 3.78 ± 0.37 B | 1.17 ± 0.22 C | 2.15 ± 0.31 B | |
20 s—4.5 cm | 2.53 ± 0.22 C | 2.88 ± 0.33 B | 1.15 ± 0.20 C | 1.88 ± 0.33 C | |
10 s—8.8 cm | 3.90 ± 0.30 AB | 4.10 ± 0.40 A | 2.20 ± 0.32 B | 2.80 ± 0.41 B | |
20 s—8.8 cm | 2.83 ± 0.27 B | 3.19 ± 0.36 B | 1.67 ± 0.25 C | 2.11 ± 0.36 B |
PUV-light treatment was performed under four different exposure conditions, i.e., different times (in s) and distances (in cm). Each treatment was replicated twice and assays were performed in triplicate. Values (mean ± SE) are given for each surface (lettuce or LDPE) and each incubation time (24 or 48 h post-inoculation), and different letters denote significant differences (P < 0.05).