Alterations in the host defense properties of human milk following prolonged storage or pasteurization.
OBJECTIVE
Preterm infants are often fed pasteurized donor milk or mother's milk that has been stored frozen for up to 4 weeks. Our objectives were to assess the impact of pasteurization or prolonged storage at -20 degrees C on the immunologic components of human milk and the capability of the different forms of human milk to support bacterial proliferation.


METHODS
The concentrations and activities of major host defense proteins in the whey fractions of mother's milk stored for 4 weeks at -20 degrees C or pasteurized human donor milk were compared with freshly expressed human milk. Proliferation of bacteria incubated in the 3 forms of human milk was assessed.


RESULTS
Relative to freshly expressed human milk, the concentrations of lysozyme, lactoferrin, lactoperoxidase, and secretory immunoglobulin A were reduced 50% to 82% in pasteurized donor milk and the activities of lysozyme and lactoperoxidase were 74% to 88% lower (P < 0.01). Proliferation of bacterial pathogens in pasteurized donor milk was enhanced 1.8- to 4.6-fold compared with fresh or frozen human milk (P < 0.01).


CONCLUSIONS
The immunomodulatory proteins in human milk are reduced by pasteurization and, to a lesser extent, by frozen storage, resulting in decreased antibacterial capability. Stringent procedure to minimize bacterial contamination is essential during handling of pasteurized milk.
Akinbi
Henry
H
Division of Pulmonary Biology and Neonatology, Cincinnati Children's Hospital Medical Center,Cincinnati, OH, USA.
Meinzen-Derr
Jareen
J
Auer
Christine
C
Ma
Yan
Y
Pullum
Derek
D
Kusano
Ryosuke
R
Reszka
Krzysztof J
KJ
Zimmerly
Kira
K
D000328:Adult; D005260:Female; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D006358:Hot Temperature; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007155:Immunologic Factors / Q000032:analysis / Q000378:metabolism*; D007781:Lactoferrin / Q000032:analysis; D007784:Lactoperoxidase / Q000032:analysis / Q000378:metabolism; D008894:Milk Proteins / Q000032:analysis / Q000378:metabolism*; D008895:Milk, Human / Q000737:chemistry / Q000276:immunology* / Q000382:microbiology; D009113:Muramidase / Q000032:analysis / Q000378:metabolism; D013242:Sterilization / Q000379:methods*; D055815:Young Adult
D007070:Immunoglobulin A; D007155:Immunologic Factors; D008894:Milk Proteins; D007784:Lactoperoxidase; D009113:Muramidase; D007781:Lactoferrin