Storage of breast milk: effect of temperature and storage duration on microbial growth

Abstract

OBJECTIVE: To study the effect of storage duration at varying temperature ranges, the pattern of microbial isolates and the quantity of colony-forming units (CFU) on expressed breast milk. DESIGN: Cross sectional study. SETTING: Bacteriology laboratory, University of Zimbabwe in Parirenyatwa Hospital, Harare. MAIN OUTCOME MEASURES: The temperature, storage duration and types of micro-organisms in freshly expressed breast milk. RESULTS: Freshly expressed human breast milk contained microbial non-pathogens of skin flora. There was no growth of organisms in stored breast milk after four hours, eight hours, 24 hours and 72 hours storage duration at temperature ranges 0 to 4 degrees C (freezing temperature), 4 to 10 degrees C (refrigerator temperature), 15 to 27 degrees C (room temperature) and 30 to 38 degrees C (high temperature) respectively. Growth was detected after the storage durations and organisms isolated were both pathogens and non-pathogens with low counts. Average colony counts was (CFU < 200). CONCLUSION: The study revealed that storage duration for expressed breast milk should not exceed 24 hours in refrigerator temperature (4 to 10 degrees C), eight hours at room temperature (15 to 27 degrees C) and four hours at high temperature (30 to 38 degrees C). Although freezing temperature (0 to 4 degrees C) seemed safest for breast milk storage, short-term storage in a freezer is not recommended due to likely the hazards of the thawing process.