Assessing Hot Water Reconstitution Practices and Labeling of Powdered Infant Formula to Enhance Microbial Safety Involving Cronobacter spp

Cronobacter spp. contamination in powdered infant formula (PIF) can cause infections in high-risk infants. Public health guidelines for caregivers of high-risk infants advise reconstitution using water heated to at least 70°C (158°F) for microbial inactivation. This study evaluated changes to water temperature under different heating and cooling scenarios during formula preparation, aiming to identify which conditions best ensure a minimum treatment temperature of 158°F (70°C). Factors such as vessel type, lid usage, vessel removal from the heat source, and water volume were tested for their effects on heat retention. The popular “hot shot” method which uses a small volume of hot water followed by a larger volume of room temperature water was also evaluated. In many scenarios, water temperatures fell below 158°F (70°C) during the preparation steps prior to PIF reconstitution. The water temperature prior to transfer to the bottle, bottle material, capacity, and volume significantly impacted temperature ( p < 0.001). The temperature of formula immediately following shaking was as high as 179.5±1.6°F (81.9±0.9°C) and as low as 138.0±1.3°F (58.9±0.7°C), depending on the preparation conditions. Bottle material and capacity, water volume, and initial water temperature significantly impacted the temperature of PIF reconstitution treatments. Small volumes (2 fl. oz) of water in small glass bottles cooled the quickest. The hotshot method yielded reconstitution temperatures below 158°F (70°C). Measuring the temperature of hot water in the baby bottle and adding PIF when it cooled to 165°F (73.8°C) resulted in formula temperatures at or above 158°F (70°C) in almost all cases. Labels from PIF products available in the U.S. were reviewed and lacked detailed information about how caregivers of high-risk infants should use hot water to reconstitute PIF. The findings of this study can help shape guidelines that improve PIF reconstitution practices.