LISTERIA outbreaks in Australia in recent years prompted the topic to be front and centre at last month’s 5th Annual Fresh Produce Safety Conference in Sydney.
Under the theme of “Food Safety: It’s Your Responsibility”, the conference brought together more than 150 food producers and manufacturers, packers, distributors and retailers, students and researchers.
Special guest speakers from across the globe delivered valuable insights to Australian producers.
Director of Food Safety, Lipman Family Farms (USA) Suresh DeCosta, said the role of food safety staff must go beyond compliance and “keeping the regulatory guys happy”.
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Mr DeCosta is also a technical committee member for the Centre for Produce Safety (USA).
At Lipman Family Farms, Mr DeCosta identified cleaning and sanitising as key issues.
Too often, he said, the job of sanitising equipment was performed as overtime by ordinary workers.
“For the job to be done properly, it needed dedicated staff, properly trained and paid a premium – a change that could only be achieved with the full co-operation of management,” he said.
At Lipmans, compliance with food safety training had been as low as 37 per cent. It’s now averaging 90pc.
“Staff should be consulted in making investments and improvements,” Mr DeCosta said.
“The food safety team need to feel they are partners.”
Listeria presents problems
THE number of deaths from the 2017 listeriosis outbreak in South Africa reached 216, making it the most lethal outbreak in history. The source was cured meats.
On a much smaller scale, Australia recently experienced lethal outbreaks traced to cheese and rockmelons.
While the number of recorded hospitalised cases in Australia is low – around 70 a year – Listeria continues to be a major problem for the food industry, and a priority theme for the Fresh Produce Safety Centre Australia and New Zealand.
Microbiologist Dr Robert Premier said there were 17 species of Listeria but most are harmless and only two are implicated in human infections.
The most dangerous is L. monocytogenes, yet even this has a virulent and non-virulent form.
Dr Premier identified three factors that made Listeria a key issue for fresh produce.
The first concerned the source of infections, for which Dr Premier said there were more questions than answers, particularly around spreading via sheep, cattle and humans.
Testing was another major factor. Rapid testing is prone to false positives, while the more rigorous Australian standard method test takes up to a week, a crucial delay during a crisis.
A third factor was the ability of Listeria to grow on the surface of fruit with inedible skins, such as rockmelons due to its natural unevenness and skin texture.
PROOF of the risk of Listeria in rockmelons came with the 2011 Colorado outbreak that resulted in 33 deaths and earlier this year in Australia which saw the deaths of seven people.
The industry, Dr Premier said, needed to better understand the potential for growth in all horticultural product lines.
While Listeria was often found in the routine testing of fresh produce – with the exception of rockmelons – it had not been linked to outbreaks in Australia.
While the differences between virulent and non-virulent strains of L. monocytogenes are still not fully understood, what has been learnt from recent outbreaks is the fresh produce and meat industries require collaboration to solve this problem.
Dr Craig Shadbolt from the NSW Department of Primary Industries said that while listeriosis was a notifiable disease, its long incubation (typically two to four weeks but up to 70 days) made it very difficult to identify the food or environmental source.
The use of whole genome sequencing, however, had been a game-changer in outbreak surveillance and detection.
The fresh produce industry needs to learn from past outbreaks to instil and adopt improved food safety practices to prevent future fatalities from listeriosis.
Dr Shadbolt highlighted the need for better understanding of the importance of washing and sanitising.
Mixing fungicide and chemical sanitiser Dr Shadbolt said, had the potential of one cancelling out the other.
The investigation into the 2018 rockmelon Listeria outbreak found that the packing house in the Griffith was hygienic and well run.
In Griffith, environmental factors were thought to have been responsible, with heavy rain and dust storms likely to have boosted the bacterial load before harvest and compromised the effectiveness of washing systems.
Extra washing to cope with soil loading and higher sanitiser concentration may help mitigate such factors in future.
“The fresh produce industry needs to learn from past outbreaks to instil and adopt improved food safety practices to prevent future fatalities from listeriosis,” Mr Shadbolt said.