Container type and bactericidal activity of human milk during refrigerated storage

Refrigeration of human milk has been recommended for its short-term storage. It has been shown that some nutritional, immunological, and bioactive properties and bactericidal activity of human milk can be altered during refrigeration. Pyrex bottles and polyethylene bags are 2 commonly used containers for human milk storage.

The aim of this study was to compare the association between storage container type on the bactericidal activity of human milk for different durations of refrigeration (fresh, and at 24 and 48 hours).

Forty-four samples of human milk were collected from 22 lactating mothers. Two samples of breast milk (approximately 10 mL each) were obtained by manual expression from each mother. One was collected directly into sterile Pyrex bottles and the other into polyethylene bags. One mL of human milk from each container was processed immediately after arrival to the laboratory. The remaining human milk was kept in the Pyrex and polyethylene containers at 4°C until analysis at 24 and 48 hours. The bactericidal activity of each sample was studied. A strain of Escherichia coli ATCC 25922 was used to determine the bactericidal effect of human milk.

Bactericidal activity was significantly reduced in milk samples stored in polyethylene bags compared to those stored in Pyrex bottles when milk samples were stored at 4°C for 24 and 48 hours (P < .05).

Short-term storage of human milk in Pyrex bottles is more appropriate than polyethylene bags for preserving its bactericidal activity against E coli.