At-Home Pasteurization of Breast Milk (Flash-Heating Guide)

If you’re obtaining breast milk from another mom (through a sharing arrangement or purchase), safety is paramount. Unlike milk from certified milk banks (which is rigorously screened and pasteurized), informally shared milk carries some risk of viruses or bacteria. Pasteurizing breast milk at home is one way to reduce these risks. A proven method is called “flash-heating.” This simple technique was developed for low-resource settings to inactivate HIV in breast milk, and research shows it can kill HIV as well as common bacteria like E. coli and Staph while preserving most of the milk’s nutrients.

Flash-heating is essentially a quick, high-temperature pasteurization. Here’s how to do it step by step:

1. 1Wash hands and use clean equipment. Pour the thawed breast milk to be treated into a clean glass jar (e.g. a mason jar). Use a volume of milk that will allow the jar to be partially submerged on its side.
2. 2Place the jar upright in a small pot. Fill the pot with cold water so that the water level is about 2 finger-widths higher than the milk level in the jar (but be careful no water gets inside the jar of milk).
3. 3Put the pot on the stove and heat. Bring the water to a rolling boil. Important: Watch the jar – as soon as the water around it reaches a vigorous boil, remove the pot from heat.
4. 4Immediately take the jar of milk out of the hot water. Do not continue heating once the water boils – the milk has been flash-heated at this point.
5. 5Cool the milk quickly. Leave the jar uncovered on the counter for about 5 minutes to release initial heat, then place the jar in a basin of cold water (or an ice bath) to drop the temperature rapidly. Quick cooling helps prevent bacteria from growing again.
6. 6Once the milk is cooled, cap the jar with a clean lid and store it in the refrigerator. Use it within 24 hours, and do not refreeze flash-heated milk.

This flash-heating method is remarkably effective: studies found it inactivates HIV in breast milk and significantly reduces bacterial counts, all without needing special equipment. In fact, flash-heating brings the milk to a higher temperature for a shorter time than standard Holder pasteurization (used by milk banks), which better preserves breast milk’s anti-infective and nutritional properties. In other words, it makes the milk safer while keeping more of those beneficial antibodies and enzymes intact.

A few notes of caution: Home pasteurization is not 100% sterilization – it greatly reduces germs but may not eliminate absolutely all spores or pathogens. Still, it’s a huge improvement for safety. Always practice good hygiene and screen donors as much as possible (ask about health history, recent blood tests for HIV, hepatitis, etc.). Flash-heating is an added layer of protection if you’re feeding your baby milk from someone else.

Many moms use this method for informal milk sharing or if they are immunocompromised. It can also be useful if you want to pasteurize your own milk (for example, mothers with certain infections have done this to deactivate a virus in their milk).

For a demonstration, check out this Flash-Heat pasteurization video: YouTube: Flash Heating Breastmilk. It shows the process of heating the jar in water until boiling and explains the technique.

By using at-home pasteurization, you’re essentially performing a mini milk-bank process in your kitchen – making donor milk safer for your baby. It’s reassuring to know that such a simple 8-minute process can kill HIV, bacteria like E. coli, and other germs while keeping your precious milk’s nutrients largely intact.