Table 2.
Microbiological characteristics of organic and conventional lettuce samples.
| Log (CFU/g) | |||||||
|---|---|---|---|---|---|---|---|
| Production Mode |
Sample | Enterobacteria | Total Counts | Lactic Acid Bacteria | Pseudomonas Spp. | Molds | Yeasts |
| Conventional | Conv1 | 6.5 | 8.0 | 3.4 | 7.7 | 4.3 | 6.0 |
| Conv2 | 4.3 | 8.3 | 4.2 | 7.4 | 4.6 | 7.2 | |
| Conv3 | 7.1 | 7.8 | 3.4 | 1 | 4.5 | 5.3 | |
| Conv4 | 4.9 | 8.0 | 3.2 | 6.4 | 4.8 | 5.6 | |
| Conv5 | 5.1 | 8.3 | 7.3 | 7.3 | 5.2 | 5.9 | |
| Conv6 | 7.0 | 8.9 | 3.9 | 7.4 | 5.1 | 5.5 | |
| Conv7 | 4.9 | 8.5 | * | 7.0 | 4.4 | 7.1 | |
| Conv8 | 6.4 | 9.2 | 4.2 | 7.1 | 4.2 | 6.4 | |
| Conv9 | 6.0 | 9.2 | 4.0 | 6.6 | 5.4 | 7.0 | |
| Conv10 | 6.8 | 7.8 | 1.0 | 6.1 | 4.9 | 5.8 | |
| Average ± SD | 5.9 ± 1.0 | b 8.4 ± 0.54 | 3.8 ± 1.6 | 6.4 ± 2.0 | 4.7 ± 0.41 | 6.2 ± 0.7 | |
| Organic | Org1 | 4.7 | 7.8 | 3.4 | 7.6 | 3.4 | 4.3 |
| Org2 | <1 | 7.2 | 3.5 | 3.7 | 4.6 | 5.2 | |
| Org3 | 6.4 | 7.5 | 2.7 | 7.5 | 5.4 | 6.1 | |
| Org4 | 3.0 | 7.4 | 1.0 | 7.2 | 4.9 | 9.2 | |
| Org5 | 4.1 | 6.1 | 1.0 | 6.0 | 2.2 | 4.5 | |
| a Org6 | 7.5 | 8.9 | 3.3 | 7.3 | 5.5 | 6.3 | |
| a Org7 | 4.3 | 7.4 | 3.6 | 6.6 | 5.0 | 5.6 | |
| a Org8 | 6.7 | 7.4 | 3.3 | 6.9 | 5.3 | 6.3 | |
| Org9 | 6.1 | 8.0 | * | 7.4 | 4.5 | 6.7 | |
| Org10 | 6.9 | 8.1 | 1.0 | 6.8 | 5.4 | 6.4 | |
| Average ± SD | 5.2 ± 1.5 | b 7.6 ± 0.72 | 2.5 ± 1.2 | 6.7 ± 1.2 | 4.6 ± 1.1 | 6.1 ± 1.4 | |
a Purchased in farmers’markets; *: not determined; SD: standard deviation; b average values for the total counts on organic and conventional lettuce samples were significantly different (p < 0.05). For all the samples, the counts of L. monocytogenes and E. coli were below the detection limit of the enumeration technique (1.0 × 101 CFU/g). Salmonella spp. and L. monocytogenes were not detected in any sample.