Composite Versus Single Sampling of Spent Irrigation Water to Assess the Microbiological Status of Sprouting Mung Bean Beds Journal of

Composite versus single sampling of spent irrigation water to assess the microbiological status of sprouting mung bean beds
Journal of the Science of Food and Agriculture
Volume 88, Issue 9, Date: July 2008, Pages: 1549-1553
Rachel McEgan 1, Susan Lee 2, Bengt Schumacher 3, Keith Warriner 1 *

1Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
2Laboratory Services Division, 95 Stone Road West, Guelph, Ontario, N1H 8J7, Canada
3Ontario Ministry of Agriculture and Food, Midhurst, Ontario L0L 1X0, Canada


BACKGROUND: Spent irrigation water testing has been recommended in sprouted seed production to detect the presence of pathogens. However, because of the heterogeneous distribution of contamination within batches of sprouted seed, taking single samples of spent irrigation water may return false-negative results. The following evaluated whether spent irrigation water collected from multiple points provided a more representative assessment of the microbiological status of the sprouting mung bean bed compared to when single samples were taken.

RESULTS: Generic Escherichia coli or Aeromonas was recovered in one and 10 of the 160 sprout samples taken from 32 sprouting mung bean batches, respectively. Composite spent irrigation water samples tested positive for generic E. coli on 19 occasions compared to 12 when single samples were taken. Mesophilic Aeromonas was detected in 13 composite spent irrigation water samples which compared to eight single samples. The prevalence of either target bacterium in composite spent irrigation water samples was not significantly (P > 0.05) different compared to when a single sample was collected.

CONCLUSIONS: Sampling spent irrigation water from multiple points under sprouting mung bean beds does not significantly increase the probability of detecting contamination, if present. The findings of the study should be considered when devising sampling plans for spent irrigation water testing in bean sprout production.