Time–temperature profiles of infant milk formula in hospitals and analysis of Enterobacter sakazakii growth

Abstract

The purpose of this study was to assess the temperature conditions in neonatal care units for the preparation and storage of infant milk formula (IMF) and infant feeding using bottles and continuous feeding syringes. Enterobacter sakazakii in IMF for feeding infants has been chosen as the subject of this study because of the high risk incurred by IMF manufacture without total microbial destruction and the high sensitivity and mortality rates of this population group. From IMF preparation till neonate feeding, time–temperature profiles of IMF samples were monitored and analysed. In order to show the health impact of this data, potential E. sakazakii growth was calculated. As IMF can be also contaminated with Salmonella, potential Salmonella growth was also calculated. However potential E. sakazakii growth data were only analysed because of E. sakazakii and Salmonella spp. data being close. The study of 25 neonatal care units in 15 hospitals showed that the final potential growth for bottles depended on different parameters: initial water temperature, room temperature where IMF was prepared, cold storage temperature and time, reheating temperature and time. One parameter was not usually enough to determine the final growth increment alone and a well-controlled and high performance stage could result in an incorrect food safety indication if the other stages are less effective. On the other hand, the final potential growth for the continuous feeding syringes depended mainly on the feeding period since the IMF was kept in a particularly high ambient air temperature (≈25 °C) in the infant’s bedroom. This stage would be controlled first (with a cold syringe cover for example); then, as for bottles, the other stages would be controlled to result in a correct food safety indication.