CUP Undergraduate Research

Date of Award


Document Type



College of Theology, Arts, & Sciences


Math & Science

Degree Name

Biology, BA

First Advisor

Dr. Gary B. Hanson


The number of infants who are breastfed is on the rise, as is the number of women in the workforce. Many women who choose breastfeeding after returning to work, express milk during the day and store this milk for a future feeding. When infants do not finish a bottle of expressed breastmilk, doctors recommend unfinished portions be thrown away. This study examined bacterial levels in expressed, partially consumed breastmilk that was stored for 48 hours at 4-6° C. A portion of unconsumed milk was examined as a control. Samples were taken every 12 hours for bacterial analysis. Tests were performed to identify total colony counts, pathogenic Staphylococci, coliforms and ß-hemolytic Streptococci. This study showed no significant difference between bottles that were partially consumed and those that were not exposed to the baby's mouth for 5 out of 6 participants. All milk samples had colony counts in the acceptable range of < 105 colony forming units per milliliter (CFU/ml). Although this project provides evidence that it may be safe to refeed a child a bottle of breastmilk, due to the small sample size, further tests should be performed.

Included in

Biology Commons