Milk Bank FAQ: Why do we need to pasteurize the milk?

August 16, 2012. Posted in: Blog Posts,Milk

Image courtesy of the Mothers' Milk Bank in Denver

Many mothers wonder why the non-profit HMBANA human milk banks pasteurize their milk. Laraine Lockhart Borman, IBCLC, with the Mothers’ Milk Bank in Denver, explains…

The HMBANA Advisory Council, a panel of experts in areas of infectious disease, microbiology, neonatology, law, and other areas, determined  that because human milk has the potential to be an agent of infectious disease, pasteurization would be required of all member banks due to the extremely fragile health of the babies receiving this milk. The number one priority is the health and safety of the tiny preterm infants served.

With any type of storage or treatment of human milk, there is some loss of its original components. Mother’s milk that has been frozen and stored experiences a loss of vitamin A from exposure to light and vitamin C from exposure to freezing temperatures. Pasteurization is a very gentle, controlled heating process using special equipment that kills viruses and bacteria while still maintaining 95% of everything that was originally in the milk. While a few of the immune properties are lost, there are many more that survive the pasteurization process. In addition, some beneficial enzymes are actually activated by the pasteurization process. *

Bottom line is that mom’s own milk is best. When this is not available, pasteurized human milk, obtained from a certified milk bank, can be a lifesaving safe and healthy alternative that everyone can feel good about.

by Laraine Lockhart Borman, IBCLC, Mothers’ Milk Bank, Rocky Mountain Children’s Health Foundation, Denver, CO

Image courtesy of the Mothers' Milk Bank in Denver

From “Donor Human Milk for Preterm Infants” (Wight 2001):

The benefits and concerns regarding the use of human milk for preterm infants has been recently reviewed, with more factors, actions, and interactions being discovered frequently… Protective effects of human milk on infection rates have been observed with the use of both fresh and pasteurized milk… 
[note: see Heiman & Schanler 2006 for a recent review]

Pasteurization (56 or 62.5°C for 30 minutes) does affect some of the nutritional, immunologic and other components of human milk. Heat treatment at 56°C (133°F) or greater for 30 minutes reliably eliminates all functional white blood cells and bacteria, inactivates human immunodeficiency virus (HIV) and human T-lymphotropic virus, and decreases the titers of other viruses, but in one study did not eliminate cytomegalovirus (CMV). Holder pasteurization [62.5°C (144°F) for 30 minutes] reliably inactivates HIV and CMV, and will eliminate or significantly decrease the titers of most other viruses.

Immunologic factors are variously affected by heat treatment. With Holder pasteurization most of the secretory IgA, bifid growth factor, and lysozyme remain (0% to 30% destroyed), lipids are unaffected, but 57% of the lactoferrin, and 34% of the IgG are destroyed. The reader is referred to a more detailed recent review (Lawrence 1999).

In general, the nutritional components are altered somewhat, resulting in slightly slower growth when compared to infants fed unpasteurized raw human milk. Holder pasteurization does not appear to influence nitrogen absorption or retention in LBW infants. Most enzymes, growth factors, vitamins, and minerals are unchanged or minimally decreased. Heat treatment of donor milk appears to foster more rapid growth of intestinal epithelial cells by inactivating heat-labile inhibitory cytokines, allowing heat-stable epidermal growth factor to act. Freezing inactivates milk cells and most viruses, but does not appear to effect the nutritional or anti-infective quality of the milk. Microwaving clearly decreases the anti-infective properties of human milk; the higher the temperature, the greater the effect.

 

* Research: The effect of pasteurization on the anti-infective agents of human milk

Percent activity remaining after pasteurization at 62.5°C for 30 minutes (unless otherwise noted)

Cells 78% macrophages Gibbs 1977
No viable cells Liebhaber 1977
Immunoglobulins
IgA (total secretory) 39%
81% (56°C for 30 minutes)
Stephens 1980
67%
77% (62.5°C for 5 minutes)
90% (56°C for 30 minutes)
Wills 1982
67% Liebhaber 1977
67%
64% (72°C for 15 seconds)
Goldsmith 1983
78% Morgan 1986
80% Ford 1977
79% Gibbs 1977
84% Goldblum 1984
86% Raptopoulou-Gigi 1977
100% Evans 1978
150% (72°C for 15 seconds) Goldblum 1984
Some loss (stable if 56°C for 30 min) Welsh & May 1979
IgG 66% Evans 1978
86%
58% (72°C for 15 seconds)
Goldsmith 1983
IgM Substantial loss Liebhaber 1977
None Goldsmith 1983
None Ford 1977
Enzymes
Lactoperoxidase 53% Friend 1983
Lipase 45% Friend 1983
Protease 27% Friend 1983
Lysozyme 61% Friend 1983
64% Gibbs 1977
67%
96% (62.5°C for 5 min)
106% (56°C for 30 minutes)
Wills 1982
76% Evans 1978
105% Ford 1977
393% (72°C for 15 seconds) Goldblum 1984
Lactoferrin 27% Wills 1982
33% Welsh & May 1979
36% Goldsmith 1983
35% Ford 1977
43% Evans 1978
123% (72°C for 15 seconds) Goldblum 1984
56% Eyres 1978
Bile salt-stimulated lipase Lost Wardell 1984
Other
Non immunoglobulin Stable Laegreid 1986
C1 – C9 Destroyed Welsh & May 1979
L Bifidus growth factor Stable
Antimicrobial activity Stable (56°C for 30 minutes) Bullen 1972
Antiprotozoal activity Some stability Gillin 1983

 

See also:  Effect of heat treatment or storage on antimicrobial factors in human milk

References

Bullen JJ, Rogers HJ, Leigh L. Iron-binding proteins in milk and resistance to escherichia coli infection in infants. Brit. Med. J. 1972; i:69-75.

Evans TJ, Ryley HC, Neale LM, Dodge JA, Lewarne VM. Effect of storage and heat on antimicrobial proteins in human milk. Arch. Dis. Child. 1978; 53:239-241.

Eyres R, Elliot RB, Howie RN, Farmer K. Low temperature pasteurization of human milk. N. Z. Med. J. 1978; 87:134-135.

Ford JE, Law BA, Marshall VME, Reiter B. Influence of the heat treatment of human milk on some of its protective constituents. Pediatr. 1977; 90:29-35.

Friend BA, Shahani KM, Long CA, Agel EN. Evaluation of freeze-drying, pasteurization, high-temperature heating and storage on selected enzymes, B-vitamins and lipids of mature human milk. J. Food. Prot. 1983; 46:330-334.

Gibbs JH, Fisher C, Bhattacharya S, Goddard P, Baum JD. Drip breast milk: its composition, collection and pasteurization. Early Hum. Dev. 1977; 1:227-245.

Gillin FD, Reiner DS, Wang, C-S. Human milk kills parasitic intestinal protozoa. Science. 1983; 221:1290-1292.

Goldblum RM, Dill CW, Albrecht TB, Alford ES, Garza C, Goldman AS. Rapid high-temperature treatment of human milk. J. Pediatr. 1984; 104:380-385.

Goldsmith SJ, Dickson JS, Barnhart HM, Toledo RT, Eitenmiller RR. IgA, IgG, IgM and lactoferrin contents of human milk during early lactation and the effect of processing and storage. J. Food Prot. 1983; 46:4-7.

Heiman H, Schanler RJ. Benefits of maternal and donor human milk for premature infants. Early Hum Dev. 2006 Dec;82(12):781-7. Epub 2006 Oct 20.

Laegreid A, Kolsto Otnaess A-B, Orstavik I, Carlsen KH. Neutralizing activity in human milk fractions against respiratory syncytial virus. Acta Paediatr. Scand. 1986; 75:696-701.

Lawrence RA. Storage of human milk and the influence of procedures on immunological components of human milk. Acta Paediatr Suppl. 1999 Aug;88(430):14-8. (Review)

Liebhaber M, Lewiston NJ, Asquith MT, Olds-Arroyo L, Sunshine P.  Alterations of lymphocytes and of antibody content of human milk after processing. Pediatr. 1977; 91:897-900.

Morgan JN, Toledo RT, Eitenmiller RR, Barnhart NM, Maddox F. Thermal destruction of immunoglobulin A, lactoferrin, thiamin and folic acid in human milk. J. Food Sci. 1986; 51:348-351.

Raptopoulou-Gigi M, Marwick K, McClelland DBL. Antimicrobial proteins in sterilized human milk. Br. Med. J. 1977; 1:12-14.

Stephens S, Dolby JM, Montreuil J, Spik G. Differences in inhibition of the growth of commensal and enteropathogenic strains of escherichia coli by lactotransferrin and secretory immunoglobulin A isolated from human milk. Immunology. 1980; 41:597-603.

Wardell JM, Wright AJ, Bardsley WG, D’Souza SW. Bile salt-stimulated lipase and esterase activity in human milk after collection, storage and heating: Nutritional implications. Pediatr. Res. 1984;18:382-386.

Welsh JK, May JT. Anti-infective properties of breast milk. J Pediatr. 1979 Jan;94(1):1-9.

Wight NE. Donor human milk for preterm infants. J Perinatol. 2001 Jun;21(4):249-54.

Wills ME, Han VEM, Harris DA, Baum JD. Short-time low-temperature pasteurization of human milk. Early Hum. Dev. 1982; 7:71-80.

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