Thesis: Development and Evaluation of Methods and Equipment to Optimize Human Milk Quality for Preterm Infants
Donor human milk is the best alternative when mothers' own milk is not available for the preterm infant because it contains nutritional, bioactive, protective and developmental components that cannot be found in infant formula. However, to prevent the potential risk for the transmission of pathogens from donor mothers to preterm infants, the donor milk is required to pasteurize before it is fed to an infant.
Holder pasteurization is widely used in milk banks. Human milk is heated in a water bath and held at 62.5°C for 30 minutes. This treatment is capable of reducing common bacteria found in human milk including E. coli, S. epidermidis, E. cloacae, B. cereus and S. aureus by a factor of 10⁵. However, bioactive proteins are only partially preserved during this process. For example, 72% of sIgA, 22% of lactoferrin and 39% of lysozyme were retained after Holder pasteurization. Furthermore, the retention of bile salt stimulated lipase (BSSL) was less than 1%. BSSL is a very heat labile enzyme and depending on exposure time the inactivation starts at 45°C which is well below Holder pasteurization temperature. It is likely that the inactivation of BSSL through the Holder pasteurization process is, in part, responsible for the lower growth rates of preterm infants fed pasteurized donor human milk compared to preterm infants fed mothers’ own milk.
Pasteurization technologies other than thermal are emerging in the food industry to preserve the sensory, nutritional and functional properties of foods. Research indicates that alternative pasteurization methods applied to human milk could prevent excessive loss of bioactive components whilst maintaining the same reduction of bacteria viability as Holder pasteurization.
Why my research is important
The focus of this project will be to develop and evaluate new methods for the treatment of human milk for the use in the neonatal care. Some of the new technologies used in this project already exists in the dairy industry and will be adapted for the use with human milk. The research in dairy industry generally focuses on microbiological and sensory qualities such as flavour and texture characteristics rather than nutritional and immunological properties. However, little is known about the effects of such treatments on human milk and its important bioactive components. The project will investigate these effects on human milk and the possible dangerous side effects these technologies could have on human milk.