Cornell researchers recommend modifications to the recipe for preparing bottles of powdered infant formula to ensure safety against rare foodborne bacteria that can be deadly for high-risk infants, thanks to a new study that analyzed the existing guidelines.
The findings, reported in a study published July 18 in the Journal of Food Protection, reveal how the current instructions for reconstituting powdered formula are ambiguous and can fail to protect against Cronobacter spp.
Cronobacter infections are of concern for high-risk infants, defined as babies under 2 months of age, preemies and those who are immunocompromised. When the bacteria contaminate powdered formulas, they can cause septicemia, meningitis and death. Cronobacter cases are rare, with an estimated 18 cases occurring annually in the U.S.
Previous studies have shown that water heated to 158 degrees Fahrenheit (70 Celsius) can kill Cronobacter. At the same time, if the water is too hot, it degrades nutrients in formula. The problem occurs when the instructions on package labels for formula preparation do not advise parents to measure the temperature. Such ambiguous preparation instructions can result in a wide range of actual temperatures used to reconstitute the powder.
"We assessed what instructions would help ensure caregivers following a series of preparation steps would use water that measured at least 158 degrees Fahrenheit," said Abigail Snyder, Ph.D. '17, associate professor of microbial food safety in the College of Agriculture and Life Sciences. Their results suggested using a thermometer to determine when the temperature of hot water in the bottle cools to 165 degrees Fahrenheit, before adding the powdered infant formula, and then waiting 1 minute before actively cooling the formula (such as, by placing a bottle under running water) helped ensure Cronobacter inactivation.
"It's important to protect our most vulnerable infants and this is an instance where caregivers have agency to make sure formula is safe," Snyder said. That's a problem, Snyder said, since current labels provide ambiguous guidelines.
Instructions don't specify when to check water temperature, if at all. For example, it's unclear whether to check temperatures before or after water is added to a bottle. "Some of the guidance just says boil and wait five minutes, which is not a temperature at all.," Snyder said. "All of these different practices change the thermal history of that water.."
The paper recognizes that caring for a newborn is difficult, and such preparation adds more work. "We're asking people to do this extra work but then the preparation protocols that are provided can result in practices that are insufficient to inactivate Cronobacter, despite all the additional effort," Snyder said. "That's the circumstance that we're trying to prevent."
Research reveals that the risk of Cronobacter infections drop after an infant reaches 8 weeks of age. So, the window of time in which caregivers must complete these extra steps is a relatively small period in a baby's life.
Maria Amalia Beary, a doctoral candidate in Snyder's lab, is the paper's first author. Co-authors include Sarah Daly, a postdoctoral research associate, and doctoral candidate Jakob Baker, both in Snyder's lab.
The study was supported in part by the U.S. Department of Agriculture.
