Flash-heating vs Flash-pasteurizing

Flash-heating (FH)1 is a low-tech method of pasteurizing breastmilk that was developed for HIV postitive mothers in developing countries who had no safe nor affordable alternatives for feeding their infants. Please see ‘How can breastmilk be pasteurized at home?’ for information on how this is done.

Studies by a research team lead by Israel-Ballard,3 have shown that FH breastmilk inactivates HIV and 4 common bacteria

In ‘HIV and Infant Feeding,’ the WHO supports heat-treating milk of HIV positive moms for temporary feeding during an emergency and when no other safe options are available.2) In a 2008 training package, the CDC also states that “HIV is killed by heating the milk and ends the risk of transmitting HIV through breast milk.”

Flash-heating is not to be confused with flash-pasteurizing (FP), a commercial process. Both are forms of High Temperature Short Time (HTST) pasteurizing, but as per the La Trobe table #7, for flash-pasteurizing, “Special equipment [is –ed.] needed for this high temperature treatment.” FP involves heating breastmilk to exactly 72ºC/161.5ºF for 15 seconds. This process is one followed by the dairy industry, and is an officially accepted method of pasteurization.3

Flash-pasteurizing has been demonstrated to inactivate bacteria as well as certain important pathogenic viruses, specifically HIV, HTLV, HBV and HCV, and CMV.

While the temperature of breastmilk when flash-heating typically reaches 72ºC/161.5ºF,4this is not as accurate as with the FP process. In a home setting, the time and temperature are not easily controlled, nor are breastmilk and water volumes.

For instance, the temperature of breastmilk when using FH will greatly vary depending on altitude and atmospheric pressure. Water boils at 100ºC/212ºF at sea level, but the higher the altitude, the lower the boiling point of water.5 Using flash-heating at home, and removing the milk from the heat when the water boils will thus not always result on the milk attaining exactly 72ºC/161.5ºF, the safe temperature needed for that type of pasteurization. We do not know how heat-treating milk at 71ºC for instance affects the viral load, except for HIV (see below).

Another aspect is that, contrary to FP where the temperature is held for 15 seconds, the whole process of flash-heating takes about 5 minutes. Holding the milk at a precise temperature for a specific amount of time is not feasible in a home setting. Both temperature and time are important however when flash-pasteurizing.

While at-home flash-heating has been researched and is proven to deactivate HIV, its effectiveness on other viruses is theoretical. HIV is destroyed at low temperatures (57ºC/134.5ºF) and so boiling water anywhere for any time will result in milk that is hot enough to deactivate the virus. While the positive results of flash-heating might be comparable to those of flash-pasteurization, when it comes to the other viruses, more research is needed to address this directly. Eats on Feets™ is seeking sponsorship for this research.

Currently there is no clear evidence on whether heat-treating breastmilk should be used as a permanent solution.6

For more information on infant feeding and HIV, please see ‘Human Immunodeficiency Virus (HIV)’ and ‘HIV and the global context of infant feeding.’

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  1. The terms flash-heating and flash-pasteurizing are often used interchangeably. Flash-heating refers to the at-home method of pasteurizing as it demonstrated in the Kiersten Ballard-Israel studies. []
  2. Per ‘HIV and Infant Feeding’: “Laboratory evidence demonstrates that heat-treatment of expressed breast milk from HIV-infected mothers, if correctly done, inactivates HIV (42–44) […] Heat treatment of expressed breast milk from mothers known to be HIV-infected could be considered as a potential approach to safely providing breast milk to their exposed infants.” (See Grade profile 6, Annex 4. []
  3. Legal pasteurization is a combination of time and temperature as per the FDA milk ordinance item 16p Administrative procedures section 1. []
  4. Per ‘Flash-Heat Inactivation of HIV-1 in Human Milk’: “Flashheating typically reached temperatures greater than 56C for 6 minutes 15 seconds and peaked at 72.9C.” []
  5. Thermometers need to be calibrated when used at higher altitudes if one were to measure the temperature of the milk. []
  6. In ‘HIV and Infant Feeding the WHO states that HIV positive mothers may consider expressing and heat-treating breast milk as an temporary feeding strategy under the following circumstances: In special circumstances such as when the infant is born with low birth weight or is otherwise ill in the neonatal period and unable to breastfeed; When the mother is unwell and temporarily unable to breastfeed or has a temporary breast health problem such as mastitis; To assist mothers to stop breastfeeding; If antiretroviral drugs are temporarily not available. []

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