Salad bags are 'breeding ground for salmonella'

Breeding ground: Ready-chopped bags of salad can increase risk of salmonella
Stephen Kelly/PA
Saphora Smith18 November 2016

Bags of prepared salad offer an optimal breeding ground for salmonella bugs, a study has found.

Damaged leaves in the bags can leak juice which boosts the growth of the food poisoning bug by up to 2,400-fold.

The juice, which attaches itself to plastic bag surfaces, can also make the bacteria more infectious than other forms of the bug.

Experts warned consumers to avoid ready-cut salad if possible, to rinse bagged salad thoroughly, and not to let it get warm.

They cautioned that salmonella attaches itself to the salad leaves so strongly that even vigorous washing would not remove all the bacteria.

Dr Primrose Freestone, from the University of Leicester's Department of Infection, Immunity and Inflammation, said: "This strongly emphasises the need for salad leaf growers to maintain high food safety standards as even a few salmonella cells in a salad bag at the time of purchase could become many thousands by the time a bag of salad leaves reaches its use by date, even if kept refrigerated.

"Even small traces of juices released from damaged leaves can make the pathogen grow better and become more able to cause disease."

She added: "We found that once opened, the bacteria naturally present on the leaves also grew much faster even when kept cold in the fridge."

Each year more than 500,000 cases of food poisoning are recorded in the UK, according to a recent report from the Food Standards Agency.

While poultry meat was the most common source of infection, some 48,000 cases were linked to fresh non-meat produce including vegetables, fruits, nuts and sprouting seeds.

For most people salmonella is just unpleasant but it can be deadly for the old, young and those with weak immune systems such as cancer patients.

The scientists did not measure levels of salmonella in bought salad but investigated the way the bacteria grew on damaged leaves and attached itself to plastic bag surfaces.

Cos, baby green oak, and red romaine lettuce, spinach, and red chard obtained from commercially available bag mixes were all used in the tests.

During the study plastic bags were cut into 2cm long sections and tested to see how well salmonella formed clinging "biofilms" on their surfaces.

According to their findings it only took two-hundredths of a teaspoon of juice to raise the threat of infection.

Create a FREE account to continue reading

eros

Registration is a free and easy way to support our journalism.

Join our community where you can: comment on stories; sign up to newsletters; enter competitions and access content on our app.

Your email address

Must be at least 6 characters, include an upper and lower case character and a number

You must be at least 18 years old to create an account

* Required fields

Already have an account? SIGN IN

By clicking Create Account you confirm that your data has been entered correctly and you have read and agree to our Terms of use , Cookie policy and Privacy policy .

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged in

MORE ABOUT