U.S – Researchers from the University of Illinois Urbana-Champaign have uncovered intriguing insights into the susceptibility of different leafy greens to E. coli contamination, shedding light on why some vegetables are more prone to bacterial growth than others, even under refrigeration.
Leafy green vegetables, including lettuce, spinach, kale, and collards, are renowned for their nutritional benefits but have also been associated with foodborne illness outbreaks, particularly involving E. coli.
Seeking to unravel the factors influencing E. coli contamination, the research team conducted a comprehensive study examining the susceptibility of five leafy greens: romaine lettuce, green-leaf lettuce, spinach, kale, and collards.
Lead author Mengyi Dong highlighted the motivation behind the study, stating, “We wanted to learn more about the susceptibility of different leafy greens.”
The team infected whole leaves from each vegetable with E. coli O157:H7 and monitored bacterial growth under varying storage temperatures.
The findings revealed that susceptibility to E. coli contamination is influenced by a combination of temperature and leaf surface properties.
While refrigeration at 4°C significantly reduced E. coli growth on lettuce, waxy greens like kale and collard exhibited the opposite trend, with slower growth at warmer temperatures but enhanced survival under refrigeration.
Moreover, the study emphasized the role of leaf surface properties such as roughness and natural wax coating in modulating bacterial attachment and growth.
“Rinsing lettuce does help, but doesn’t remove all the bacteria because of their tight attachment to the leaf,” Dong explained.
Antimicrobial properties of kale, collard juice
Interestingly, the researchers discovered that spinach, kale, and collard juice displayed antimicrobial properties against E. coli, offering protection against bacterial contamination.
Leveraging this discovery, the team isolated juice from kale and collards and applied it to lettuce leaves, demonstrating its potential as a natural antimicrobial agent for controlling foodborne pathogens.
Co-author Pratik Banerjee highlighted the broader implications of the research, emphasizing the importance of embracing best practices in the food industry and supply chain to mitigate foodborne illness risks.
He highlighted the collaborative efforts within the research community and federal agencies to address food safety concerns, ensuring the overall safety of the U.S. food supply.
The study’s findings pave the way for potential applications in food safety practices, including the development of antimicrobial sprays or coatings to control foodborne pathogen contaminations at both pre-harvest and post-harvest stages.
In harnessing the natural properties of leafy greens, researchers aim to enhance food safety measures and mitigate the risk of bacterial contamination in fresh produce, ensuring consumer health and well-being.
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