Study: Refrigeration effective in preventing E. coli on lettuce, not kale and collards
lettuce from E. coli contamination, but not kale and collards — types of saag — a new research has found. Seeing outbreaks on lettuce but not on kale and other brassica vegetables like broccoli, cabbage, cauliflower, collard greens and others, researchers analysed the tendencies of leafy greens to get infected with E. coli, or Escherichia coli, a bacterium species found in lower intestines of humans. While generally harmless, some of its strains are occasionally responsible for food contaminations and can cause food poisoning.
The researchers at the University of Illinois at Urbana-Champaign, US, infected whole leaves from five leafy greens — romaine lettuce, green-leaf lettuce, spinach, kale, and collards — with E. coli (serotype O157:H7) and observed what happened after storing them under these temperatures — 4 degrees Celsius (refrigeration), 20 degrees Celsius (room temperature) and 37 degrees Celsius (normal body temperature).
Overall, a combination of both temperature and leaf surface properties such as roughness and the natural wax coating were found to govern susceptibility to the bacterial contamination, the researchers found.
«At room temperature or higher, E. coli grows very fast on lettuce, but if lettuce is refrigerated at 4 degrees Celsius, we see a sharp decline in the E. coli population. However, for waxy greens like kale and collard, we get the opposite results.
»On these vegetables, E. coli grows slower under warmer temperatures, but if it is already present, it can survive longer under
