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Study shows link between unrefrigerated caramel apples and Listeria

Fall is in full swing and with it comes an abundance of tasty fall treats, one of such being caramel apples. Recent studies, however,  have revealed a potentially fatal health risk linked to consuming them unrefrigerated . Researchers at the University of Wisconsin-Madison’s Food Research Institute found that the sticks poked into caramel apples, if left at room temperature, may eventually harbor toxic levels of Listeria monocytogenes. 

Listeria infection is associated with headaches, fever, gastrointestinal symptoms, and in severe cases, death. The study’s findings may provide an explanation to an outbreak of Listeria linked to caramel apples  last year that killed seven people and left at least 35 more gravely ill.

Kathleen Glass, a researcher involved in the study, stated that “the outbreak took  producers, public health officials, and food safety experts by surprise” as apples themselves are typically too acidic for bacteria to thrive. Glass and her colleagues wondered if the sticks used to puncture the apples were somehow at fault. Would puncturing the apples release enough juice to cause the moisture that allows Listeria to grow?

This led to an experiment that involved placing strands of Listeria onto unsuspecting Granny Smith apples.  The apples were then dipped into hot caramel, half of them with sticks in, and the other half were without.

Glass and her team found that after exposure that the  caramel apples without sticks showed no signs of Listeria monocytogene growth, whereas refrigerated caramel apples punctured with sticks were subject to pathogen growth at a much slower rate. However, those that were left at room temperature with the sticks in experienced a significant increase in pathogen growth.

Glass also mentions that while the hot caramel might kill most of the surface bacteria, that there is still a risk of growth in regards to the strands of surviving bacteria that might have managed to escape unharmed.

“If someone ate those apples fresh, they probably would not get sick. But because caramel-dipped apples are typically set out at room temperature for multiple days, maybe up to two weeks, it is enough time for the bacteria to grow,” she explained in an article published by CBS News.

A statistic provided by the Centers for Disease Control and Management estimates that, in the United States alone, there are approximately 260 deaths annually caused by complications related to Listeria.

To avoid risk of infection, Glass recommends that caramel apples be eaten fresh or, alternatively, for consumers to pursue the treat only if it has been refrigerated. The obvious solution would be to simply remove the sticks prior to consumption, but that would be too messy, now wouldn’t it?



About Cindy Pereira

Cindy Pereira is a recent graduate of the Professional Writing program formerly offered at Grant MacEwan University in Edmonton, Canada. When she isn't dishing out the news, she can be found scrawling poetry, watching films, and drinking copious amounts of tea.