(I-345) Microfluidic UV-C Treatment of Human Milk to Inactivate Pathogens.

Introduction:: We explored how UV-C light could be used to inactivate pathogens in human milk. Human milk is typically treated using thermal pasteurization which leads to protein denaturation. UV-C light is a promising non-thermal alternative that preserves proteins and may improve infant nutrition. UV-C light is not commonly used to pasteurize or sterilize milk due to milk’s high opacity which limits UV-C light penetration beyond the surface layer. To overcome this limitation, we constructed a microfluidic device to direct the milk through a channel with a height of roughly 400 microns (Figure 1A-B) which would enable UV-C light to fully penetrate this thin fluid layer. We aimed to design a microfluidic process that would achieve a minimum of a 5-log reduction of neonatal pathogens after a single pass through this channel.

Materials and Methods:: Human milk inoculated with relevant neonatal pathogens (Enterococcus faecium, Staphylococcus aureus and Bacillus cereus spores) was pumped into the device using a series of increasing flow rates (2.25 - 9 mL/min). At each flow rate, milk samples were collected after UV-C treatment and bacterial survivors were analyzed using standard serial dilution and plate counting methods. Three replicates of each UV-C treatment (flow rate) were conducted for each bacterial target. The device was sterilized between each replicate.

Results, Conclusions, and Discussions:: Figure 1C displays microbial reduction as a function of milk flow rate. All flow rates achieved an average bacterial reduction of >5-log for all targeted neonatal pathogens, including B. cereus spores that were tested. In general, lower flow rates yielded higher log reductions due to the higher UV-C dosage due to increased channel residence time. These results indicate that UV-C light is effective at inactivating neonatal pathogens, including spores, in human milk when pumped through our microfluidic device. Future studies will examine the integrity of proteins in the milk treated with UV-C providing insight into whether this method could be used to manage infection risk while improving nutritional quality. Additional experimentation is underway to evaluate channel thickness and maximize flow rate to optimize device throughput.

Acknowledgements (Optional): : This study was funded by the National Institute of Health (grant no. 5R01HD106140).


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