Effect of storage and heat on antimicrobial proteins in human milk.

Human milk, after storage and pasteurisation at 73 degrees C for 30 minutes at a milk bank, was found to have little surviving IgA, IgG, lactoferrin, lysozyme, and C3 complement. Accurate pasteurisation at 62.5 degrees C produced a loss of 23.7% of the lysozyme, 56.8% of the lactoferrin 34% of the IgG, but no loss of IgA. Storage by deep freezing at -20 degrees C for 3 months produced no appreciabile loss of lactoferrin, lysozyme, IgG, IgA, or C3.