How do sprouts become contaminated?
Public health scientists believe that the seeds used for sprouting are the most likely source of contamination. Salmonella or E. coli bacteria can lodge in tiny seed cracks and are difficult to eliminate. These bacteria can multiply during sprouting in warm, humid conditions. Poor hygienic practices in the storage of seeds and in the production of sprouts have also been the cause of past sprout-related outbreaks. Most sprouts such as alfalfa sprouts can only be eaten raw, which means they are not exposed to temperatures high enough to kill bacteria that may be present. Some sprouts, such as mung bean sprouts, can also be eaten cooked. Recently, in 2005, an outbreak of salmonellosis in Ontario was linked to the consumption of raw and lightly-cooked mung bean sprouts, such as found in some stir-fries.