Fresh produce an emerging food safety challenge

A Lincoln expert is reminding the public to put their fruit and veges in the fridge and wash them to avoid food poisoning.

Professor of Toxicology, Ravi Gooneratne, says contamination of fresh produce is emerging as a major food safety challenge.

Generally, processed ready-to-eat and cold-stored meat and dairy products are considered high-risk foods for L. monocytogenes bacterial infections that cause human illness in the form of listeriosis.

However, recently, several listeriosis outbreaks have been linked to fresh produce contamination around the world. Additionally, studies have detected L. monocytogenes in fresh produce samples and even in some minimally processed vegetables.

Professor Gooneratne says the greatest risk is when fresh vegetables and fruits are consumed without being washed.

It is also important to store vegetables under a controlled low temperature that increases shelf-life and inhibits bacterial growth.

Professor Gooneratne has co-authored a recent paper and an article in science journal Food in collaboration with Dr Malik Hussain in Food Authority of New South Wales, Australia, on the threat.

He says the incidence of foodborne outbreaks caused by contaminated fresh fruits and vegetables has increased in recent years.

Most outbreaks have been reported in the USA, Europe, Canada, and to a lesser extent in Australia and New Zealand.

“These foodborne outbreaks are not only a burden on public health but also cause heavy economic loss to the food industry”.

He says several groups of microorganisms can colonize or contaminate fruits and vegetables at any point in the food supply chain. Pathogenic microorganisms such as E. coli, Salmonella, L. monocytogenes and norovirus are commonly associated with contaminated fresh produce.

Various types of fresh produce including cantaloupe, strawberries, mangos, leafy green vegetables, lettuce, salad mixes, sprouts, cabbage, cut celery and radishes are potential vehicles for transmission of pathogens.

The severity of listeriosis can range from mild gastroenteritis to severe disease conditions (septicaemia, encephalitis, meningitis, abortions and stillbirths) and can result in a high fatality rate in immune-compromised populations. Some people have a higher risk for developing listeriosis, such as the elderly.

The mortality rate can be 20%–30% for those who contract listeriosis.

Professor Gooneratne says innovative business opportunities and product diversity that appeal to the consumer may also increase food safety risks.

“Cut fruits and vegetables have a higher microbial risk profile than the ‘whole’ produce. Therefore, it is not surprising that delicatessen salads made up of the same vegetables can be more contaminated.”

“One of the problems associated with fresh produce is that, unlike tinned or packaged foods, there is a lack of information on the shelf-life and expiration dates,” he says.

There are also risks associated with fresh produce sold by street vendors.

Potatoes exposed directly to the sun can result in solanine production and consumption of foods containing solanine can result in nausea, vomiting, diarrhea, headache, dizziness, and fever. In more severe cases, hallucinations, paralysis and even death can result.

When exposed to rain and sun at over 20 degrees C, Salmonella, E. coli or L. monocytogenes will multiply to toxic levels in cauliflower.

He says consumption of fresh fruits and vegetables is important for a balanced diet and healthy life-style.

“It is important to understand the nature of fresh produce safety challenges, contamination sources, risks to the consumer, and approaches to eliminate or reduce the level of contaminants.

“Scientific understanding is rapidly evolving in this important area of food safety.”

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