Killing Salmonella in Seconds

The new weapon to prevent food poisoning outbreaks

Eating raw cookie dough off the spoon is a cherished childhood memory for many but the stomach ache that possibly followed may not be remembered as fondly.

Salmonella is one of the most common forms of bacterial food poisoning in the United States and eating foods such as raw or undercooked eggs, meat and sometimes even fruits and vegetables can lead to infection or serious illness.

According to the Centers for Disease Control and Prevention, late last year more than 400 people across 44 states in the US were infected with Salmonella linked to contaminated cantaloupes. That outbreak claimed six lives. Officials also believe the number of people who fell ill was likely to be much higher than reported, as some people may not have sought medical treatment.

While that outbreak is now over, Salmonella continues to be a common health issue worldwide, causing nasty symptoms such as diarrhoea, fever and stomach pains that usually start between 12 to 36 hours after exposure and last up to a week.

“Vulnerable people such as young children, the elderly, pregnant women and people with weakened immune systems are most at risk of severe consequences and could even die of food-borne illnesses,” said Dr Katharina Richter, a Future Making Fellow from the University of Adelaide’s Institute for Photonics and Advanced Sensing and the Adelaide Medical School.

Dr Richter is part of a team of University of Adelaide researchers who are developing a new weapon in the fight against Salmonella – transforming plasma-activated water into a food sanitiser that can then be applied to at-risk foods before they are sold to the consumer.

“The results of our prototype trials are really exciting and showed that our sanitiser destroyed Salmonella on chicken meat and eggs in under one minute,” said Dr Richter.

“We envisage that this sanitiser could be used as a spray or dip for at-risk foods such as eggs, meats, poultry and plant-based products during the manufacturing process, potentially providing a chemical-free alternative to current sanitisers and preventing disease.”

The researchers created the plasma-activated water in the lab by using a plasma generator. This produced a range of reactive oxygen and nitrogen species and ions that reduced the pH of the water, giving it antimicrobial properties.

Dr Andrea McWhorter, a food and veterinary microbiologist from the University of Adelaide’s School of Animal and Veterinary Science, is also involved in the development of this potential solution to a common health problem. Her research focuses on understanding how food-borne bacterial pathogens such as Salmonella and another common cause of gastroenteritis called Campylobacter, survive through the food supply chain, ultimately causing disease in humans.

“Raw poultry can often be contaminated with Campylobacter and Salmonella bacteria which can be easily spread to other surfaces. If we can kill them before they reach the consumer, we could significantly reduce the number of food poisoning cases, making food safer, improving public health and possibly even saving lives,” she said.

While food grade sanitisers are currently used to wash both chicken meat and eggs before they are sold to consumers, there is still potential for bacteria to develop resistance to certain types of sanitisers and cause illness in humans.

“Our plasma-activated water solution is eco-friendly and will provide a new, more sustainable form of defence against the superbugs. Crucially, it won’t change the smell or taste of the food because once the active ingredients have reacted, they are inactivated leaving behind only pure water,” said Dr Richter.

The eco-friendly nature of this promising sanitiser is an additional benefit, but it’s potential could be even greater with researchers exploring whether a version of the plasma activated water could be used as an effective wound cleanser for chronic wounds such as diabetic foot ulcers. The first clinical trials for this therapeutic application are expected to commence this year.

While the University of Adelaide’s plasma-activated water solution is certainly showing promise as a Salmonella slayer, it is not yet commercially available.

The World Health Organization advises all people to take precautions when preparing and eating food, including ensuring food is properly cooked and hot when served, washing hands thoroughly with soap, and making sure fruits and vegetables are washed well before eating, particularly if you’re planning on eating them raw.

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