Bacteriostatic qualities of human milk

Area of Science:

• Microbiology
• Human Lactation
• Food Safety

Background:

• Working mothers often express human milk for infant feeding.
• Refrigeration is not always available for expressed milk storage at work.
• Concerns exist regarding bacterial growth in human milk at room temperature.

Purpose of the Study:

• To assess the bacteriostatic quality of human milk stored at room temperature.
• To determine safe storage durations for expressed human milk without refrigeration.

Main Methods:

• Quantitative cultures of human milk were performed at 0, 2, 4, 6, and 24 hours post-expression.
• Milk samples were collected from two groups: colostrum (less than 6 days postpartum) and mature milk (7-42 weeks postpartum).
• Milk was stored at ambient room temperature throughout the study.

Main Results:

• Bacterial counts (colony-forming units/mL) did not significantly increase in mature milk stored at room temperature for up to 6 hours.
• Bacterial counts did not significantly increase in colostrum stored at room temperature for up to 24 hours.
• No significant increase in bacterial contamination was observed within 6 hours for either milk type.

Conclusions:

• Expressed human milk can be safely stored at room temperature for up to 6 hours.
• Working mothers can confidently use expressed milk for their infants within a 6-hour window without refrigeration.
• This finding addresses a practical concern for breastfeeding mothers in the workforce.