Researchers from the University of Sydney and the University of California, Davis, are collaborating on a project to reduce the risk of food poisoning outbreaks associated with raw produce.
Foods like salad crops and fruit are a surprisingly common cause of illness and diarrhea. Earlier this year 80 cases of food poisoning were linked to rockmelons grown in the Northern Territories. Another 43 people ended up in hospital after eating Australian-grown mung bean sprouts, and 140 people became sick after eating packaged salad greens. All three cases involved Salmonella poisoning.
In many cases, says Robyn McConchie, Professor of Horticulture and Pro-Dean in the Faculty of Agriculture and Environment, the contamination is caused by organic soil amendments – particularly chicken manure, which comes laden with Salmonella unless it is thoroughly composted.
“Salmonella is the second leading cause of food-borne illness in Australia,” says Professor McConchie. “If vegetable farmers store chicken manure next to their fields, the Salmonella can easily blow onto their crops or contaminate them via irrigation water.”
Working with Dr Trevor Suslow, an extension research specialist in the Department of Plant Sciences at UC Davis and a leading figure in food safety in the US, Professor McConchie and her team have been researching the remediation of soil contaminated by Salmonella. Funding has been provided by Australia’s Horticulture Innovation Ltd and the Center for Produce Safety in the US.
Their work has already produced valuable findings for farmers: that Salmonella dies off much more quickly in sandy soil than in clay loam; that high temperatures above 37⁰C cause a die-off of Salmonella in only 28 days; that solarisation using plastic covers is effective in eliminating Salmonella, but cover crops have little effect; and that the presence of manure in the soil promotes the survival of Salmonella.
“We are looking to make science-based recommendations for growers so they can make a quick return to safe crop production,” says Professor McConchie. “UC Davis has been a terrific partner in our research. This is an area for which they are internationally renowned.”
Dr Suslow is also one of the partner investigators in a food safety project being run by the Faculty of Agriculture and Environment with the help of a $2.2 million Australian Research Council Industrial Transformation Training Centre grant.
The research will take place over four years and will focus on nine areas identified as priorities by the fresh produce industry. It will provide opportunities for 13 PhD and three postdoctoral students, and will involve collaboration with the University-based Fresh Produce Safety Centre.