Urbana, Ill. – Just recently sprouts were linked to a massive and tragic E. coli outbreak in Europe.
But now scientists at the University of Illinois have found that the key to keeping sprouts free of foodborne pathogens lies in industry’s attention to cleaning the seeds.
The researchers conducted a study using new technology to assess and compare the safety of radish, broccoli and alfalfa sprouts.
The research has been published in the Journal of Food Science.
Once the seeds have germinated, says Hao Feng, an associate professor of food and bioprocess engineering, it’s too late.
“Sprouts are extremely complex structures with a forest-like root system that conceals microorganisms. Just a few E. coli cells can grow to a substantial population during germination and sprouting and it’s very difficult to get rid of them all,” says Feng.
In his experiments, Feng used both the Food and Drug Administration’s recommended dose of chlorine to kill microorganisms and a new sanitizer that was a combination of surfactant and organic acid.
Feng used some sophisticated technology to also determine the seeds’ surface structure. This allowed him to calculate each seed’s surface roughness.
E. coli could be eliminated on the alfalfa seeds because of their relatively smooth surface, but broccoli and radish seeds have rough surfaces. Their texture renders these rougher seeds more susceptible to the attachment of pathogens and makes these microorganisms very difficult to remove, says Feng.
Low doses of irradiation can be successfully used on broccoli and radish seeds, but that treatment runs the risk of losing sprouts’ quality and nutritional value.
And sprouts do have immense nutritional value. Broccoli sprouts have been linked to cancer prevention; radish sprouts have lots of vitamins A and C, notes Feng.
He also found that better results were achieved with broccoli sprouts when the sanitizer is used on small batches rather than large ones.
Feng says sprouts are carefully tested for the presence of pathogens and entire batches are thrown out when any positive result is detected.
He does suggest some ways these sprouts could be more safely incorporated into consumers’ diets.
Cooking them can kill pathogens but some of the sprouts’ nutritional punch is lost.
Using sprouts in dishes that use natural antimicrobials, such as vinegar, garlic, green onion, and spices, can inhibit the growth of E. coli, even kill pathogens, but there is still some risk involved, says Feng.
Feng says ultimately the research demonstrates the importance of eliminating all pathogens on seeds before sprouting.
“The food industry must maintain very strict control in the sprout production process, focusing on the cleanliness of seeds and expending money and effort on prevention. Then consumers can be assured that these nutritious food products are safe to eat,” Feng said.