Use of spent irrigation water for microbiological analysis of alfalfa sprouts

Numerous outbreaks of foodborne illness have been linked to the consumption of raw sprouts. Sprout producers have been advised by the Food and Drug Ad ministration to include microbiological testing of spent irrigation water d uring production as part of an overall strategy to enhance the safety of sp routs. Alfalfa sprouts and irrigation water were analyzed to show the feasi bility of using irrigation water for monitoring the microbiological safety of sprouts. Sprouts and water were produced and harvested from both commerc ial-scale (rotary drum) and consumer-scale (glass jars) equipment. Rapid in creases of aerobic mesophiles occurred during the first 24 h of sprouting, with maximum levels achieved after 48 to 72 h. The counts in irrigation wat er were on average within approximately 1 log of their respective counts in the sprouts. Similar results were obtained for analysis of Escherichia col i O157:H7 in irrigation water and sprouts grown from artificially inoculate d seeds. Testing of spent irrigation water indicated the contamination stat us of alfalfa sprouts grown from seeds associated with outbreaks of Salmone lla infection.