Good Fruit Grower

July 2016

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Page 24 of 39 Good Fruit Grower JULY 2016 25 W hole genome sequencing has gone a long way toward helping scientists track foodborne illness back to the source. That's good for consumers who want assurances that food they eat is safe. At the same time, however, it's causing increasing concern for growers who realize that the technique could potentially implicate a region or any orchard or vineyard, including their own. Fruit growers have become especially anxious in light of three things: —The 2014 illness outbreak that was linked to apples. —The recent use of whole genome sequencing to track not only current disease outbreaks, but also past sporadic clinical cases to their sources as a means of identifying responsibility for low-level but chronic contamination. —The use of evidence gained from whole genome sequencing to initiate criminal investigations against those connected with illness-causing foods. Caramel apples A 2014 listeriosis outbreak tied tainted caramel apples to 34 hospitalizations and three deaths. Listeriosis is caused by infection with the pathogenic bacterium Listeria monocytogenes. This marked one of the first times that whole genome sequencing had been used to pursue a foodborne-illness outbreak to its origin. It led to a voluntary recall of Gala and Granny Smith apples, and it showed growers and packers that dangerous illnesses can take root in all kinds of fresh produce, including tree fruit. The question of who was to blame led to some tense moments, particularly since Listeria is a microorganism that exists just about anywhere in the great outdoors, said Kathleen Glass, distinguished scientist and associate director of the Food Research Institute at the University of Wisconsin–Madison. "Apple trees grow out in the open. An orchard is not a sterile environment, so you are going to have Listeria show up every once in a while." There is no evidence to determine whether apples may have initially been exposed to the bacterium in the orchard, but ample evidence that the specific L. monocytogenes causing illness and death was present in the packing facility. As a result, the responsibility for the caramel-apple outbreak fell mainly on the packers, she said. "Ultimately, it was the packer who got into trouble because they didn't have the next level of cleaning and sanitation that they should have had," Glass said. The manufacturers also shared the problem. She explained, "When it came to the manufacturers who made the caramel apples out of the contaminated apples, at least one used another sanitation step and assumed it worked, but nobody had a validated sanitation step." Validation is key, Glass noted. "This is where we're really behind the beam. Many packers and processors are doing things they think will be good, but they don't really have proof that they are." Growers may not have been singled out as contributing to this particular outbreak, but Glass said they should nevertheless be cognizant of Listeria and ways they can mitigate it. "This is an instance where apples, and produce in general, is just a really difficult type of food product, because we don't have a magic bullet yet to eliminate Listeria. All you can do is try to reduce the level of contaminants that are there." (See "Protect your customers, protect your orchard" on page 29.) Whole genome sequencing tracks pathogens, perhaps to your door. by Leslie Mertz Don't get caught with your plants down! Hot New Varieties Trees? 2018 2017 Apples * Cherries * Pears Call today to place your order! 503-538-2131 • FAX: 503-538-7616 • 800-421-4001 We've got you covered!

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