What happens to bacteria when you freeze breast milk?

Quick Summary: Recent research suggests freezing breast milk for any length of time can impact the bacteria present in the milk — with less impact on the bacteria in short-term frozen milk when compared to long-term frozen milk.

What happens to bacteria when you freeze breast milk?

A small feasibility study by Shirin Moossavi et al. (2021) was amongst the first to use culture-enriched molecular profiling to study culturable bacteria in breast milk.

The research team included Dr Meghan Azad (who is featured in our Breast Milk course).

The researchers compared the differences in bacteria — comparing samples from fresh breast milk, breast milk frozen for a short time (2 weeks) and breast milk frozen for a long time (over 6 months).

{A bacterial culture is a method of multiplying bacteria by letting them reproduce in in a special media conducive to their growth. Bacterial cultures are used to determine the type and abundance of bacteria in the sample. }

The study:

8 samples of breast milk were collected from mothers of babies admitted to a neonatal intensive care unit (the Neonatal Intensive Care Unit (NICU), McMaster Children’s Hospital, McMaster University).

• Fresh samples were…