A recent investigation by the University of Illinois Urbana-Champaign delves into the factors influencing E. coli contamination across various leafy greens, including romaine and green-leaf lettuce, spinach, kale, and collards. Mengyi Dong, the study's lead author, highlights the frequent outbreaks associated with lettuce compared to the lower susceptibility of brassica vegetables like kale and collards. Conducted within the university's Department of Food Science and Human Nutrition, the research involved exposing whole leaves to E. coli O157:H7 and analyzing the effects of different storage temperatures.
The study reveals that temperature and leaf surface characteristics, such as roughness and wax coating, play crucial roles in bacterial growth. Lettuce showed a rapid increase in E. coli at room or higher temperatures, but refrigeration significantly reduced bacterial presence. Conversely, kale and collards exhibited slower E. coli growth at warmer temperatures and greater survival rates when refrigerated. Notably, these vegetables' natural resistance to E. coli is enhanced by their typical cooking process, unlike the raw consumption of lettuce.
Source: aces.illinois.edu
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