Dangerous bacteria may still lurk in unreachable parts of fruit and veg even after a thorough dousing.

Washing your fruit and vegetables before you eat them is recommended to remove potential pathogens such as E.coli and Salmonella, but new research indicates that this may not be enough as some bacteria can survive the water.

Researchers from Purdue University, US, looked at E.coli in mung bean sprouts and Salmonella in peanut seedlings after contaminating them before planting. What they found surprised them – the pathogens had worked their way into the tissues of the plants, even the tissue responsible for transporting nutrients.

Although researchers have tried to assess this possibility before, it has proven difficult as slicing open a plant could transfer pathogens from the outside to the inside making it impossible to say whether the bacteria were actually inside the plant. This new study worked around this problem by freezing the location of the bacteria within the plant tissues before cutting the samples.

Wash your fruit and veg

So what can you do to prevent yourself coming into contact with these bacteria? Cook your fruit and veg. While the inner tissues may still contain the pathogens, boiling or steaming produce to 74 degrees Celsius (165 degrees F) will kill the bacteria making them safe to eat.

Eating fresh fruit, however, presents bigger problems as heating it to high temperatures will kill certain vitamins, such as C, for example.

So what should you do? “I’d recommend that people take sensible precautions and wash their fruit thoroughly, and then just enjoy them,” says registered nutritionist Dr Carina Norris. “Although there is a chance that you could be taking in germs, the likelihood of becoming ill is very small. I’d hate to see people avoiding fruit because they’re worried about illness – the good fruit can do for your health far outweighs any tiny potential danger.”