Refrigeration Ideas for Reducing E. Coli Contamination in Lettuce


Refrigeration Tips for Lowering E. Coli Contamination in Lettuce

A current research investigates the elements influencing E. coli contamination on 5 distinct leafy greens: romaine lettuce, green-leaf lettuce, spinach, kale, and collards.

“We’re seeing lots of outbreaks on lettuce, however not a lot on kale and different brassica greens. We needed to be taught extra concerning the susceptibility of various leafy greens,” mentioned lead creator Mengyi Dong, now a postdoctoral analysis affiliate at Duke College. Dong carried out the analysis as a doctoral pupil within the Division of Meals Science and Human Vitamin (FSHN), a part of the Faculty of Agricultural, Shopper and Environmental Sciences (ACES) on the U. of I.

Affect of Temperature and Leaf Floor Properties on E. coli Susceptibility in 5 Greens

The researchers contaminated entire leaves from every of the 5 greens with E. coli O157:H7 and noticed what occurred after storage at 4° C (39° F), 20° C (68° F), and 37° C (98.6° F). General, they discovered that susceptibility was decided by a mix of temperature and leaf floor properties reminiscent of roughness and the pure wax coating.

“At room temperature or greater, E. coli grows very quick on lettuce, but when lettuce is refrigerated at 4° C (39° F), we see a pointy decline within the E. coli inhabitants. Nonetheless, for waxy greens like kale and collard, we get the other outcomes. On these greens, E. coli grows slower beneath hotter temperatures, however whether it is already current, it could survive longer beneath refrigeration.”

Rinsing lettuce does assist, Dong mentioned, however doesn’t take away all of the micro organism due to their tight attachment to the leaf.

Did You Know?

Leafy inexperienced greens function important suppliers of dietary fiber and vitamins, but they’ll host dangerous pathogens. Lettuce, specifically, has ceaselessly been linked to outbreaks of foodborne sickness all through america.

The researchers additionally inoculated minimize leaves with E. coli O157:H7 to match the intact floor of an entire leaf to the broken floor of a minimize leaf.

“Complete leaves and freshly minimize leaves current totally different conditions. When the leaf is minimize, it releases vegetable juice, which comprises vitamins that stimulate bacterial progress,” Dong defined. Nonetheless, the researchers discovered that spinach, kale, and collard juice really exhibited antimicrobial properties that shield towards E. coli.


To additional discover these findings, they remoted juice (lysate) from kale and collards and utilized the liquid to lettuce leaves, discovering that it may be used as a pure antimicrobial agent. The potential functions may embrace antimicrobial spray or coating to manage foodborne pathogen contaminations at each pre-harvest and post-harvest levels, the researchers mentioned.

“We are able to’t fully keep away from pathogens in meals. Greens are grown in soil, not in a sterile setting, and they are going to be uncovered to micro organism,” mentioned co-author Pratik Banerjee, affiliate professor in FSHN and Illinois Extension specialist.


“It’s a fancy downside to resolve, however we will embrace greatest practices within the meals trade and meals provide chain. There’s lots of curiosity from the analysis neighborhood and federal businesses to handle these points, and the USDA imposes excessive requirements for meals manufacturing, so total the U.S. meals provide is kind of secure.”

Banerjee and Dong emphasize they don’t need to discourage folks from consuming contemporary fruit and greens; they’re a part of a nutritious diet. Simply observe meals security pointers, wash your lettuce completely, retailer it within the fridge, and take note of any meals security remembers in your space, they conclude.




Leave a Reply

Your email address will not be published. Required fields are marked *