Study Finds Salmonella in Ready-to-Eat Salads

A UK study has found that ready-to-eat bagged salads can be an ideal breeding ground for harmful Salmonella bacteria.
December 2, 2016

You might think that Salmonella is a bacteria only found in potentially hazardous foods, like meat and poultry. In fact, incorrect cooking of these foods is the most common cause of Salmonella poisoning. 

However, a UK study has found that ready-to-eat bagged salads can also be an ideal breeding ground for the harmful bacteria.

Pre-prepared salads are becoming more and more popular with supermarket sales on the increase, so the University of Leicester’s findings that they can potentially pose severe health risks, are serious cause for concern.

If salad leaves have direct contact with fertiliser, pests or animals in the field, if they are not properly washed, or come into contact with dirty water, they can become contaminated with Salmonella.

The study, published in the journal Applied and Environmental Microbiology, used salad juices in water to mimic the ready-to-eat salad bag environment and found that the movement of individual Salmonella enterica bacteria more than doubled. 

In fact, the increase in movement also facilitated rapid growth of the bacteria; refrigerated, 100 Salmonella bacteria multiplied to around 100,000 in just five days.

Because salad is usually grown in open fields, it can become contaminated through contact with insects, bird faeces and manure.

While this form of contamination is rare, it is essential to ensure good food hygiene and washing practices are performed to prevent a Salmonella outbreak.

The Food Safety Information Council recommends always washing salad leaves before consumption, even if they have come from a ready-to-eat pre-washed salad bag. 

Stuart Hilditch, CEO of the Australian Institute of Food Safety, said: “This study highlights just how important it is to keep our food handling staff trained in food safety to ensure that the prevention of food-borne illness outbreaks is always front of mind.”

The symptoms of Salmonellosis usually present themselves within 12 to 36 hours, but they could start as soon as 6 hours after consuming contaminated food, or may take up to 72 hours to present themselves.

The most common symptoms of Salmonellosis include:

  • Diarrhoea
  • Vomiting and Nausea
  • Fever
  • Headache
  • Stomach Cramps

To find out more about Salmonella and Salmonellosis, read our article Everything You Need to Know About Salmonella.