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Table 4 Effect of washing methods on the reduction of faecal coliform and helminth eggs levels of lettuce irrigated with polluted water (n = 10 for each method)

From: Microbiological quality of lettuce (Lactuca sativa) irrigated with wastewater in Addis Ababa, Ethiopia and effect of green salads washing methods

Indicator organisms Washing methods
T0 T1 T2 T3 T4
Faecal coliform (log10 MPN 100 g−1) 4.23x (0.71)a 3.43 (0.77)b 3.35 (0.61)b 2.54 (0.51)c 2.58 (0.43)c
Helminth eggs (eggs 100 g−1) 2.2y (1.93) 0.8 (1.14) 0.6 (0.70) 1.0 (1.33) 0.6 (0.97)
Actual egg count (range) 0–6 0–3 0–2 0–4 0–3
  1. (T0): Control (unwashed) (T1) Potable tap water washing and rinsing (2 min); (T2): Potable tap water washing - rinsing (2 min) followed by dipping in 40 ppm salt solution (1 min); (T3): Potable tap water washing - rinsing (2 min) followed by dipping in 15 000 ppm vinegar solution (1 min); and (T4): Potable tap water washing - rinsing (2 min) followed by dipping in a combined 40 ppm salt and 15 000 ppm vinegar solution (1 min)
  2. xActual mean faecal coliform level
  3. yActual mean egg count
  4. Figures in parenthesis represent standard deviation
  5. Values in the same row with different letters differ significantly (P < 0.05); range of detected helminth eggs too narrow for normal distribution, homogeneity, and statistically significant differences