| | Percentage of Activity Remaining * |
| | Heat Treatment
(15 seconds) | Heat treatment
(30 minutes) | Refrigeration
(7 days) | Freezing
(3 months) |
| 72°C **
Flash
Pasteurisation | 62.5°C
"Holding method"
Pasteurisation | 56°C | 4°C | -15°C |
| Secretory IgA | 85 | 70 | 85 | 100 | 100 |
| IgM | | 0 | | | Decreased |
| IgG | | 70 | | 95 | Decreased |
| Lactoferrin (Iron-binding capacity) |
100 | 40 | 75 | | 100 |
| Complement C3 | | 0 | 0 | | 90 |
| Milk cells | 0 | 0 | 0 | | 10 |
| Lyzozyme | 100 | 75 | 100 | | 90 |
| Vitamin A | | 100 | 100 | | 100 *** |
| Lipases (generate antimicrobial lipids) | 3 | 0 | | 75 | 50 |
Other factors ****
(oligosaccharide, etc.) | 100 | 100 | 100 | 100 | 100 |
| Bacteriostatic activity (on added E. coli) |
| Some decrease | Some decrease | No decrease | Decreases
at 1 month, 66% present at 3 months. |
| Cytomegalovirus | Nil | Nil | Can be
some | Gone in a quarter of samples in 24 hours, all gone by 7 days | Gone in most samples after 24 hours, others decreased by 99% in 3 days. |
| Skin bacteria | 99% gone | Nil | Nil | Same | Decreased |
* Values indicated are maximum values
** Special equipment needed for this high temperature treatment
*** Minimum of 3 weeks
**** These survive over 80°C for >30 minutes, while other listed factors are totally destroyed
- HIV is destroyed by milk pasteurisation. HIV-1 is reduced ten-fold at 56°C for 121 seconds and
at 62.5°C for 10 seconds in liquid; hepatitis B is killed and hepatitis C almost eliminated in
serum at 60°C for 10 hours; parvovirus B19 (similar to TTV) is removed at 60°C for 3 hours or
30 minutes at 70°C in liquid.
- HTLV-1 (all cell-associated) is destroyed within 20 minutes at 56°C (or 10 minutes at 90°C),
or by freezing at -20°C for 12 hours. Cell associated HIV provirus DNA is destroyed by bringing
milk to the boil. Boiling milk destroys the immunoglubulins, lactoferrin, lysozyme and the milk's
bacteriostaic activity, but not the peptide beta defensin-1.
- Pretoria pasteurisation (J. Trop. Ped. 2000, 46: 219) has been devised
in an attempt to kill HIV, by standing milk (50-150ml) in a glass jar in 450ml of preboiled water.
The milk temperatures can remain between 56-62.5°C for 10-15 minutes. Similarly, single bottle
pasteurisers are available where basically boiling water is added to a thermos flask containing the
milk in a plastic bottle. A temperature of 58°C is reached in five minutes and held at 60°C
for 30 minutes. A solar-powered device can also pasteurise HIV-infected milk at 60°C for
30 minutes (J. Soc. Gynacol. Inv. 2000, 7: 366).
Rehandling of the pasteurised milk can recontaminate it.
- Mature milk stored at room temperature for up to 6 hours (27-32°C) does not normally have any
increase in bacterial counts. However, S. epidermidis may have proliferated in a warm
environment during collection and transport (see Table 5).
- Normally milk is not stored at 4°C for more than 48 hours and heat treated milk is stored frozen.
- Pasteurisation should kill all parasites which are rarely found in breast milk. Pasteurising human
milk with T. cruzi trypomastigotes inactivates the parasites.
- Reconstituted infant formula will rapidly grow V. cholerae, S. flexneri and
S. entertidis at 30°C but not if refrigerated.
- Very LBW babies are fed from milk banks with fresh frozen
unpasteurised milk from donors who are also CMV-IgG negative
- After pasteurisation, milk has been contaminated with Pseudomonas aeruginosa when bottles
(even with tight lids) were cooled in cold water containing the organism.
Also, 14 infants had symptomatic infection with four dying of P.
aeruginosa that contaminated milk from a pasteuriser and bottle
warmer during thawing of milk. Klebsiella pneumoniae has also
cross-contaminated pasteurised milk.
Based on a table in the Proceedings of Breast Feeding: The Natural Advantage
Conference. October, 1997. Sydney. © J.T. May and Nursing Mothers' Association of Australia.
November, 1997.
