Salmonella Update: Bagged salad at risk according to new study

Published: 21 Nov 2016

Following the recent E.coli outbreak involving rocket leaves, a study conducted by Leicester scientists have uncovered that bagged salad carry's a high risk of the growth of food poisoning bacteria, including Salmonella.

The study uncovered that the moist environment combined with nutrients leaching out of chopped leaves created the perfect breeding ground for bacteria. Research showed that the bacteria could even thrive in refrigerated conditions, people are advised to eat bagged salad on the day they buy it.

Bags are often kept moist to help keep the salad crisp and fresh, and the plants have often been chopped into individual leaves for convenience. The study showed sugars, proteins and minerals escaped from the cut leaves into the water in the bag.

The study, published in Applied and Environmental Microbiology, showed that an initial contamination of 100 Salmonella bacteria would increase to 100,000 within five days.

Under the circumstances, the following advice has been reported on the BBC website:

  1. Don’t keep bagged lettuce beyond their 'Use By' date
  2. Eat the bagged lettuce on the date of purchase
  3. Avoid lots of mushed leaves and if it's inflated then don't use it.

Dr Freestone told the BBC News website: "Juices that naturally leach from the leaves have the potential to increase the growth of any pathogen that might be present and establish them so strongly that washing wouldn't be enough to eradicate them."

As previously reported earlier in the year an E.coli outbreak associated with mixed salad leaves resulted in a total of 161 cases of E.coli infections with more than 60 cases requiring hospital treatment and 2 fatalities.

How can you reduce the risk of getting infected with E.coli?

  1. Personal hygiene – practice good hand washing procedures, especially after visiting the toilet, after touching animals, handling raw meats etc.
  2. Ensure that the wash hand basin is equipped with antibacterial hand soap, a supply of both hot and cold running water and a means to dry hands.
  3. Thorough cleaning of fruit and vegetables is critical to ensure that any loose soil and germs are removed.
  4. A good segregation system needs to be put in place to ensure that raw and cooked/ready to eat food items are stored separately.
  5. Ensure that food items, especially meat, are thoroughly cooked.

In light of the current and ongoing investigations, CSC are advising the following control measure be put in place to limit exposure to E.coli O157:

  1. Ensure that all food handlers practice good personal hygiene practices with specific focus placed on hand washing practices.
  2. All vegetables, including salad leaves, intended to be eaten raw should be thoroughly washed. The use of chlorine wash can also be used.
  3. Alternatively, the use of mixed salad leaves (including rocket leaves) must be removed from the menu until the investigation into the E.coli O157 has been concluded with the source identified.

If you require any additional support regarding the prevention of E.coli O157, please do not hesitate to contact us