The time is ripe for Salmonella
4 May 2012
The ripeness of fruit could determine how food poisoning bacteria grow on them, according to research presented by Imperial researchers at the Society for General Microbiology’s spring conference in Dublin on 26 March. Their work could lead to new strategies to improve food safety, bringing many health and economic benefits.
A wide range of fresh produce has been linked to outbreaks of Escherichia coli and Salmonella enterica, including melons, jalapeño and serrano peppers, basil, lettuce, horseradish, sprouts and tomatoes.
The researchers, led by Professor Gad Frankel (Life Sciences), are looking at how these bacterial pathogens latch onto fruits and vegetables and establish themselves in the first place. They have discovered that strains of Salmonella behave differently when attached to ripe and unripe tomatoes.
“Bacteria that attach to ripe tomatoes produce an extensive network of filaments, which is not seen when they attach to the surface of unripe tomatoes. This could affect how they are maintained on the surface,” explained Professor Frankel. “We are not completely sure yet why this happens; it might be due to the surface properties of the tomatoes or alternatively the expression of ripening hormones.”
Although fresh fruits and vegetables are recognised as important vehicles that transmit harmful bacteria, they are still important components of a healthy and balanced diet.
“By and large, raw fruits and vegetables are safe to eat and provide numerous health benefits. By working out the reasons behind sporadic outbreaks of infections, we can control these better and help maintain consumer confidence. By improving food safety we would also see important economic and health benefits,” Professor Frankel said.
— Simon Levey, Communications and Development