Related Experiment Video
Updated: Jul 13, 2026

Individualized Reconstitution of Human Milk Microbiota: A Feasible Approach in Real-World Settings
Published on: February 7, 2025
Effect of environmental conditions on unpasteurized donor human milk
David J Rechtman1, Martin L Lee, H Berg
1Prolacta Bioscience, Inc., Monrovia, CA 91016, USA. drechtman@prolacta.com <drechtman@prolacta.com>
Abstract:
As a result of concerns over the transmission of infectious diseases by donor milk, as well as the possible loss of nutritional value of donor milk through exposure to a variety of environmental conditions, the practice in the United States has been to discard unpasteurized donor milk that has thawed or sat for several hours at room temperature or in the refrigerator rather than (re)freezing it. We undertook an experiment to measure the effects of ambient temperature conditions and refreezing on the bioburden and nutritional content of human milk. We conclude that unpasteurized human milk is robust and can be used after storage under certain conditions.
Related Concept Videos
Pasteurization and Food Preservation
Microbes in Food Production
Development of Human Microbiota
Principles of Food Preservation
Factors Influencing Microbial Growth: Temperature
Physical Methods for Controlling Microbial Growth: Temperature

