Consuming unrefrigerated caramel apples ups Listeria infection risk, according to new research published in the mBio journal.
Caramel apples, a popular treat and snack, particularly around holiday season, seem to fall out of grace. Last year, seven people died due to Listeria infected caramel-coated apples, while another 35 cases of infection were reported.
What makes these fruits so susceptible to the bacteria and its development? Typically, apples aren’t an inviting environment for the Listeria bacteria due to their high acidity levels. However, as the researchers observed, once they are coated in caramel and the juice is stirred by the sticks poked in the fruits, they become the nursing spot for the dangerous bacteria.
Kathleen Glass with the University of Wisconsin-Madison and author of the new study stated in relation to last year’s Listeria outbreak:
“The outbreak took producers, public health officials and food safety experts by surprise: caramel-coated apples are not a food on which Listeria monocytogenes should grow”.
This was the incentive for the new research which found that it is the released juice that provides the moist environment for the dangerous bacteria to grow. The experiment conducted by the researchers was fairly simple.
Picking a handful of Granny Smith apples, the researchers checked for Listeria monocytogenes at first. With none discovered, they then pierced the apples with the sticks used to handle the sticky caramel apples. Hot caramel was poured over them and left to harden. The caramel apples were then split in two batches. A third batch was covered in caramel, but the sticks were not introduced to produce the juice.
One was left at room temperature over a period of days, while the second was refrigerated. Meanwhile, both batches were checked for bacterial growth.
The experiment resulted in refrigerated caramel apples that had no sticks showing no signs of Listeria growth. The caramel apples batch that had been pierced and refrigerated showed slow growth of the bacteria.
Most importantly, the batch left at room temperature was found to contain significant traces of Listeria bacterial growth within just three days. In light of these findings, researchers warn that when choosing caramel apples it’s perhaps safer to ask if they’ve been refrigerated or not and look for those that don’t have the sticks already inserted.
If you’re preparing them at home, you know what you have to do. Listeria causes serious health conditions and symptoms, particularly with children and the elderly and people who have a weakened immune system.
According to the CDC, 1,600 U.S. residents are infected with Listeria yearly, while 260 die due to the infection.
Photo Credits: Flickr