Research conducted in 2010 found that Listeria monocytogenes was not predominantly spread by water and chicken manure, two common farm inputs in Australian vegetable farming. It is however more prevalent in summer and in particular in Victoria.
Silage and baled hay produced high numbers of L. monocytogenes which are fed to and ingested by ruminants (cows, sheep, goats). This issue with this feed is that it passes through the animals usually without causing infection to them and becomes trapped within dust when the faeces become dry in hot weather.
The dust carrying the L. monocytogenes can then settle on and contaminate vegetables after being blown large distances by strong winds. Leafy vegetables (eg. curly parsley) can trap dust more effectively and show higher levels of detection than smooth leaf vegetables, such as cos lettuce.
A project recommendation is that intensive livestock operations (feedlots) and grazing cattle, sheep and goats should be kept as far from vegetable production as possible and particularly in the direction of prevailing summer winds.
There can be unintended additional contents, also known as physical contaminants and foreign objects, in fruit and vegetable purchases. Growers aim to eliminate these from the fresh produce sent to retailers and processors. Most retail and food service specifications have a zero tolerance for pests, dead or alive, or other physical contaminants. Consumers also have a low tolerance of additional contents.
Physical contaminants is a broad category that includes but is not limited to soil, stones, sticks, weeds, insects, frogs, glass, nails, plastic and rubber, pens, pins, paper clips and jewellery. Some are a social media novelty while others have genuine injury potential. Some come from the environment and others are from harvest, handling and packing. Some can result in withdrawals, recalls and negative media coverage.
A series of Q&A’s below address the topic of contamination of pests and objects.
Produce Retailer: Panelists at the Center for Produce Safety Symposium described better traceback as essential to containing foodborne illness outbreaks and urged companies to invest in that infrastructure. The somber and frank discussion, moderated by Produce Marketing Association CEO Cathy Burns, started with a review of the recent spate of E. coli outbreaks linked to romaine lettuce. Burns asked each member of the group to share his biggest takeaway from the romaine debacle.
Global Food Safety Resource: More than half of the secret to recovering from a pathogen-related product recall lies in being prepared before it even happens, according to Keith Warriner, a professor of food science at Canada’s University of Guelph. “Have a recall team that includes someone with decision-making authority,” he says, noting that, depending on the company, the team should also have staff from quality assurance, production, marketing and distribution.
Stuff.co.nz: New Zealanders were surprised to learn that those forces for good in human health – lettuce and carrots – were identified as a common link in the outbreak of Yersinia infections that made at least 220 people sick and sent 70 to hospital in 2014. [T]he source of the New Zealand outbreak was never proven, and this was mainly because of the difficulty of tracing all the ingredients of a mixed salad.
Queensland Country Life: Converting water-holding “dump tanks” to dry dumps has emerged as a common recommendation for rockmelon growers in order to prevent another listeria outbreak. Growers have also been advised on correct cleaning practices and encouraged to embrace automation to further avoid a repeat of the listeria outbreak which crippled the industry a year ago.
Food Safety News: Federal officials won’t say definitively that contaminated canal water was behind this year’s deadly E. coli outbreak linked to romaine lettuce, but they are saying they “found no evidence in support of alternative explanations.” Another point made clear in an outbreak investigation report released yesterday puts the FDA firmly on record when it comes to antiquated shipping and receiving recordkeeping used by many in the leafy greens industry.
ABC News: Given a choice, what do you use: a paper towel or an electric hand dryer? Or do you wipe your hands on your jeans and walk out the door? The paper-towel-vs-hand-dryer debate makes headlines whenever a study comes out in favour of one or the other. Look at who doles out the money for these studies, though, and you’ll see it’s usually the “winning” side. Still, universities and research institutions do (hopefully) conduct the research independently, even if they receive industry funding. So let’s take a look at what they say.
WebMD: A massive recall involving nearly 4 million pounds of salads, wraps, and other products has been traced to a common supplier of onions and other vegetables. McCain Foods, headquartered in Canada, announced that its fire-roasted, caramelized, or sauteed frozen vegetables and fruits made at its Colton, CA, facility may have been contaminated. The products were sold in Trader Joe’s, Whole Foods, Walmart, Kroger, and Target stores across the country.