Technology that allows vegetables to be cleaned with electricity-charged water before harvest is being trialled in South Australia.
The University of South Australia research could also help keep irrigation pipes clean and give growers the ability to irrigate with water previously deemed too poor to be used on vegetables.
Electrolysed Oxidising water techniques (EO) are used to sanitise water used on produce post-harvest to kill bacteria and extend shelf life but using it pre-harvest at large scale is a new concept.
The water is sanitised when it passes electrodes, which convert chloride salts already present or added to the water into chlorine.
The three-year project began in June and is being funded by Hort Innovation Australia. Growers in South Australia and New South Wales have been recruited for on-farm trials.
University of South Australia Chair in Environmental Science and Engineering Enzo Lombi said the technology was scalable and could be used to sanitise thousands of litres of water an hour – enough to service entire farms.
He said the technology would be most effective at treating leafy crops that are consumed fresh such as lettuce, spinach and parsley.
“The technology basically converts the chloride that may be already present in the water or can be added to the water into hypochlorous acid (chlorine), which is a very strong oxidising agent that kills off the micro-organisms,” Professor Lombi said.
Lombi said the research would mainly look at human pathogens like salmonella and ecoli but will also look out for any positive effects at eliminating crop diseases.
“With more and more demand for food safety now is the right time to test it out and it should be cheap enough so it is affordable for farmers,” he said.
The sanitised water would also help clean biofilms from irrigation pipes and allow farmers to access water sources not previously deemed suitable for irrigation because of high microbial content.
Lombi said the EO water was also certified organic and could play a significant role in organic farming.
“I’m sure there will also be some unexpected things we find along the way and the follow-up might be that we find that it is also useful as an alternative to pesticides in organic farming,” Prof Lombi said.
“We have a pretty heavy laboratory component where we can do some really detailed studies on whether it works for example to reduce the risk of pathogens growing on crops. In the second and third year we will continue with the lab studies while we also have on-farm trials at a least two locations.”
The vegetable industry is one of the Australia’s largest horticultural industries with an annual production of about 3.5 million tonnes and a value of $AU8.7 billion.
Hort Innovation chief executive John Lloyd said the effectiveness of EO water as an irrigation treatment had not yet been fully evaluated.
“This research will fill that knowledge gap and deliver some tangible outcomes that will benefit growers,” he said.
“It has the potential to unlock benefits such as the ability to easily treat irrigation water from a variety of sources, using a safe and proven method, and the potential effective removal of sludge and build up in irrigation pipes.”
Lloyd said Australia had some of the strictest food safety standards in the world.
“Growers want to build on these standards even further by investing in research to stamp out product recalls and maximise consumer confidence. An additional layer of food safety protection can only help achieve that.”